SAES-422 Multistate Research Activity Accomplishments Report
Sections
Status: Approved
Basic Information
- Project No. and Title: S299 : Enhancing Production and Reproductive Performance of Heat-Stressed Dairy Cattle
- Period Covered: 01/01/2003 to 12/01/2003
- Date of Report: 05/25/2004
- Annual Meeting Dates: 02/14/2004 to 02/15/2004
Participants
West, Joe (jwest@tifton.cpes.peachnet.edu) - University of Georgia; Smith, Terry (trsmith@ads.msstate.edu) - Mississippi State University; Ward, Jerry (jward@agcenter.lsu.edu) - LSU AgCenter; Edwards, Lynette (jedwards@utk.edu) - University of Tennessee; Whisnant, Scott - North Carolina State University; Willard, Scott (swillard@ads.msstate.edu) - Mississippi State University; Godfrey, Bob (rgodfre@uvi.edu) - University of Virgin Islands; Kellogg, Wayne - University of Arkansas; Williams, Justin - Mississippi State University; Hamernik, Deb - USDA-CSREES; Morrison, David (dmorrison@agcenter.lsu.edu) - LSU AgCenter
The meeting came to order at 8:15 am on February 14 in Tulsa, OK with a welcome and self-introductions. The agenda and related information for the meeting were approved. David Morrison stressed that this was an important meeting in the life of the project as it was the midterm meeting. He stressed that it was important to make future plans for the project if it was to continue. There are two options: 1) extend the project one year if it was incomplete, or 2) begin the process of writing another project. It was decided to begin the process of writing. There are numerous deadlines that must be met to initiate another project. The group agreed that it would be beneficial to meet during the National Animal and Dairy Science Meeting in St. Louis to discuss writing responsibilities. David Morrison gave an update on the mid-term review of the project conducted in January at the Department Heads Meeting. The review committee was pleased with the science that was being conducted but was concerned about the lack of shared protocols and overall lack of collaboration. The group has a better understanding of the need for shared protocols and increased collaboration. Deb Hamernick gave an update on personnel changes at USDA, the Competitive Grants Program, the USDA grants budget and the Presidents proposed budget for next year.
The remainder of the Saturday sessions was spent sharing reports from research conducted last year. A general discussion of suggestions for areas of research and collaboration for the new project lead to a number of ideas (in the complete minutes). It was mentioned that more effort should be expended looking for grants and funding to support work done under this project. A working mission statement was developed as well as a rough schematic showing the areas of research and the interaction between them. To facilitate collaboration, a questionnaire for the group to build a facilities, laboratory, and capabilities database will be distributed. A discussion was held to identify collaborative areas of research for the coming year.
The 2005 annual meeting schedule was discussed and the date set. Bob Godfrey agreed to host the meeting at UVI. The dates were set for May 22-23 with participants arriving on the afternoon of Saturday May 21. The meeting adjourned at noon on February 15.
The remainder of the Saturday sessions was spent sharing reports from research conducted last year. A general discussion of suggestions for areas of research and collaboration for the new project lead to a number of ideas (in the complete minutes). It was mentioned that more effort should be expended looking for grants and funding to support work done under this project. A working mission statement was developed as well as a rough schematic showing the areas of research and the interaction between them. To facilitate collaboration, a questionnaire for the group to build a facilities, laboratory, and capabilities database will be distributed. A discussion was held to identify collaborative areas of research for the coming year.
The 2005 annual meeting schedule was discussed and the date set. Bob Godfrey agreed to host the meeting at UVI. The dates were set for May 22-23 with participants arriving on the afternoon of Saturday May 21. The meeting adjourned at noon on February 15.
Accomplishments
Objective I:
A. Effect of environmental stressors on body temperature, nutrient intake, and performance.
Accomplishment: Vaginal temperature was not different (P > 0.10) between dark and light Holstein cows for coat color (Godfrey-VI). Peak skin and vaginal temperatures lagged behind peak environmental temperature by 157 and 278 min, respectively. Temperature under white or black hair and vaginal temperature were correlated with environmental temperature (P < 0.0001; r = 0.38, 0.38 and 0.21 respectively). Dark cows tended to have higher (P < 0.07) maximum black coat temperatures than did light cows.
Wetting cows decreased body temperature and increased milk production (Ward-LSU). There were larger milk responses in older cows compared with heifers, and cows responded to sprinkling to a greater degree than heifers in the afternoon. Cows and heifers that were sprinkled had slightly higher body temperatures in the morning. The sprinklers were turned off at 7 pm and all animals had the same amount of cooling during the night time. With the greater milk production the assumption was that sprinkled cows were consuming more feed and the increased heat of fermentation caused by increased feed intake led to the slightly higher body temperatures in the morning.
Temperatures of bedding (sand, rice hulls, and a mixture of sand and rice hulls) were measured in 36 free stalls used by lactating cows (Kellogg - AR). Additionally, SandTrapTM devices were used to hold bedding in all of the stall or in only one-half of the stall. The air temperature averaged 31.5oC outside and 29.1oC inside the free stall barn. Sand bedding was warmer in the front of the stalls when the entire SandTrapTM was used (30.4 vs. 31.8oC), but bedding temperatures at the back of stalls did not differ between use of one-half and entire SandTrapTM devices.
Accomplishment: The effects of cooling Holsteins during the prepartum period were investigated using 30 cows (Ward, LA). One half of the cows were housed under fans and sprinklers and the other half only had access to shade. Cooling had no effect on body temperature or DMI prior to calving and had no effect on milk production after calving. However, cooling prior to calving decreased DMI after calving.
B. Effect of environmental stressors on reproductive performance.
Accomplishment: Progress in characterizing components of the oocyte altered by elevated temperature has been made (Edwards, TN). Heat shock did not alter nuclear maturation as culture at 41ºC for up to 24 h and did not alter progression of the oocyte to metaphase. Heat shock did not alter membrane integrity as culture at 41ºC for up to 24 h, did not alter proportion of oocytes recovered, lysed, or having an intact membrane after cumulus denudement. Heat shock did alter a number of components within the egg cytoplasm. Cortical granule types were altered after heat shock suggesting possible alterations in the cytoskeleton. Glutathione content was elevated in the oocyte after heat shock suggesting possible increases in free radicals. Retinol improved the development of oocytes compromised by heat stress.
C. Effect of genetic selection on heat tolerance or intolerance.
Accomplishment: Days open (DO) records from GA, TN and NC were analyzed accounting for heat stress via a norm-reaction model (Misztal, GA). The shape of the heat index for DO was close to sinusoidal with the highest value in April and the lowest value in October. Genetic and residual variances and heritabilities were highest for spring calvings and lowest for fall calvings. The variance associated with the highest level of heat index was 33% of the genetic variance under no heat stress. Genetic correlation between regular and heat stress effects was 0.67.
Studies have addressed the interaction between coat color (black versus white percentage) and heat stress on thermal heat load in dairy cattle (Godfrey - USVI). Pictures of cows on heat stress trials during the summer of 2003 (Willard, MS) have been acquired, and will be analyzed in cooperation with Godfrey - USVI and included as a parameter in study analysis and future experimental designs. These studies thus far have identified advantages in dairy cattle with a greater percentage of white hair-coat relative to their thermal tolerance.
A survey of genotypes expressing increased tolerance to heat shock at the cellular level is underway (Hansen - FL). In cooperation with this aim, the production performance and genotypic differences in Gir (Bos indicus) x Holstein and Holstein cattle are being evaluated (Willard-MS). Cross-bred heifers and bulls have reached one-year of age as of this progress report, and growth curves are being analyzed relative to Holstein companions. Gir x Holstein heifers are currently being added to the breeding herd for artificial insemination to Holstein sires, and crossbred bulls are being ejaculated to assess timing of puberty and ejaculate quality.
D. Effect of heat stress and production level on endocrine profiles.
Accomplishment: The concentrations of metabolites and hormones during the 12 weeks after calving in dairy cows calving in either summer (August) or winter (January) were compared (Whisnant - NC). Serum P4 concentrations increased earlier in winter indicating an earlier first ovulation. Levels of non-esterified fatty acids and beta hydroxy butyrate were higher and cholesterol was lower in summer cows. These may indicate that summer cows were in a poorer nutritional state than winter cows. Serum leptin concentrations were higher in summer cows, which may reflect photoperiod differences. Concentrations of glucose, insulin and plasma urea nitrogen (PUN) and thyroxine (T4) did not differ between seasons. Thyroxine and PUN levels increased gradually over time in both groups.
Objective II:
A. Effect of nutritional strategies to enhance intake and efficiency of nutrient utilization and improve reproduction in hot, humid climates.
Accomplishment: The effect of feeding a fibrolytic enzyme or yeast on production and energy sttus of lactating Holsteins was investigated (Smith, Willard, MS; Ward, LA) Dietary treatments were: 1) fibrolytic enzyme (7g/d in LA; 15 g/d in MS), 2) 113 g/d yeast or 3) controls. In LA, dietary treatment had no effect on DMI, milk production, milk composition, or blood NEFA or glucose concentrations. In MS, cows supplemented with yeast and Fibrozyme averaged 4.2% and 9.3% greater feed intake than controls and during the final 3 weeks of the study, the difference in feed intake became more pronounced for cows supplemented with Fibrozyme; in this period their intake averaged 15% greater than controls. The dietary supplements used had no impact on cow body temperatures or respiration rates.
Accomplishment: Trials investigated the relationship between DCAD (25 or 50 meq Na+K-Cl/100 g DM) and dietary crude protein (CP) concentrations (14.5 or 16.8% CP) and the relationship between DCAD (25 or 50 meq/100 g DM) and protein degradability (15% CP with either 33 or 42% of CP as undegradeable intake protein (UIP)(West, Bernard, GA). Increasing DCAD improved DMI and yield of milk, fat, protein. Blood bicarbonate was higher and urinary N was lower for the high DCAD. An interaction was observed between DCAD and UIP for DMI and yield of milk, fat, and protein because of improved intake and yield for high DCAD at 33% UIP where intake and yield were similar for both DCAD concentrations at 42% UIP. Urinary urea N excretion was greater for low DCAD and for 33 versus 42% UIP.
B. Effect of hormonal supplements to enhance reproductive performance in hot, humid climates.
Accomplishment: Studies have been conducted (Godfrey-USVI; Whisnant-NC; Willard-MS) to evaluate supplemental GnRH administration post-breeding on endocrine profiles and pregnancy rates in heat stressed dairy cows and heifers. Results have been variable among location with respect to pregnancy rates and further analysis is continuing.
Accomplishment: Administration of GnRH to heat stressed dairy cows on either day 5, or day 5 and 11 after insemination to a timed AI in heat stressed dairy cows was tested (Whisnant-NC). A similar treatment was performed in winter for comparison. During summer, the temperature-humidity index (THI) values averaged 76.0, which is considered mild heat stress. Serum P4 was increased by GnRH administration in both groups. Pregnancy rates were higher in the cows receiving GnRH on both days 5 and 11 (35.7-2.4%) than in controls (14.5-1.5%) and in cows receiving GnRH on day 5 only (22.8-5.5%). In winter, GnRH administration increased serum P4 concentrations but had no effect on pregnancy rates. Pregnancy rates were 25% in both controls and the day 5 group and 33% for the day 5 and 11 group. Although not a planned comparison, serum P4 concentrations were higher in control (no supplemental GnRH) cows in winter than in control cows sampled during the summer. This seasonal difference was also seen in other treatment groups, confirming earlier reports of lower P4 in cows under heat stress conditions.
C. Effect of environmental modifications on lactational and reproductive performance in hot, humid climates.
Accomplishment: To characterize the impact of tunnel ventilation cooling on lactation performance during periods of hot weather (Smith, Willard-MS). A 10-week trial, which began June 2, 2003, compared two groups of 10 cows housed in the tunnel ventilation barn with two similar groups, housed in an adjacent traditional freestall barn, cooled by shade and fans alone. Tunnel ventilation cooling decreased exposure to moderate heat stress conditions by 4.3 hours/d when compared to conditions in the traditional freestall barns. Cows housed in the tunnel barn had dramatically lower peak body temperatures (1.2 OF) and respiration rates (15.7 breaths/min) than cows housed in the outside freestall barn. Cooling improved feed consumption an average of 4.0 lbs/hd/d. In addition, cows receiving the tunnel ventilation cooling averaged 5.9 lbs/hd/d greater milk production than cows cooled with shade and fans alone.
Cows housed in a tunnel ventilation barn were compared for reproductive performance with a similar group of cows housed in an adjacent traditional freestall barn, cooled by shade and fans alone (Smith, Willard-MS). Cows were synchronized using 2-injections of PGF2a over 14 d, and observed continuously for signs of estrous activity. The average duration of estrus was shorter for cows in the tunnel barn than for those housed outside 6.78+0.87 h vs. 10.33+3.24 h, respectively. Cows in the tunnel barn tended to exhibit signs of estrus earlier in the day than cows housed outside. The pregnancy rate was 37.5% for cows housed in tunnel barn and 25% for cows housed outside.
The use of fans only and fans plus sprinklers was explored to evaluate animal production in relation to size of cow (Large or Small); Willard,MS). The cows were housed in a free stall barn. Rectal temperatures, dorsal and ventral infrared temperature (DIR and VIR) and ventral infrared temperature (DIR and VIR) and respiratory rates did not differ in relation to size of the cow. However, the cows in the fan and sprinkler groups had lower rectal temperature, VIR, DIR, and respiratory rate than the cows in the fan only group. Milk production followed the same pattern with size of the cow having no affect, but the groups that were cooled with the fan and sprinkler produced more milk throughout the trial. Daily income per cow was greatest for the small animals cooled by fan and sprinkler followed by the larger animals cooled with fan and sprinkler, the small cows cooled by fans, and then the large animals cooled by fans. In addition when the economics of the cooling systems and DMI were calculated, daily income per cow was greatest for the small cow fan and sprinkler group.
A. Effect of environmental stressors on body temperature, nutrient intake, and performance.
Accomplishment: Vaginal temperature was not different (P > 0.10) between dark and light Holstein cows for coat color (Godfrey-VI). Peak skin and vaginal temperatures lagged behind peak environmental temperature by 157 and 278 min, respectively. Temperature under white or black hair and vaginal temperature were correlated with environmental temperature (P < 0.0001; r = 0.38, 0.38 and 0.21 respectively). Dark cows tended to have higher (P < 0.07) maximum black coat temperatures than did light cows.
Wetting cows decreased body temperature and increased milk production (Ward-LSU). There were larger milk responses in older cows compared with heifers, and cows responded to sprinkling to a greater degree than heifers in the afternoon. Cows and heifers that were sprinkled had slightly higher body temperatures in the morning. The sprinklers were turned off at 7 pm and all animals had the same amount of cooling during the night time. With the greater milk production the assumption was that sprinkled cows were consuming more feed and the increased heat of fermentation caused by increased feed intake led to the slightly higher body temperatures in the morning.
Temperatures of bedding (sand, rice hulls, and a mixture of sand and rice hulls) were measured in 36 free stalls used by lactating cows (Kellogg - AR). Additionally, SandTrapTM devices were used to hold bedding in all of the stall or in only one-half of the stall. The air temperature averaged 31.5oC outside and 29.1oC inside the free stall barn. Sand bedding was warmer in the front of the stalls when the entire SandTrapTM was used (30.4 vs. 31.8oC), but bedding temperatures at the back of stalls did not differ between use of one-half and entire SandTrapTM devices.
Accomplishment: The effects of cooling Holsteins during the prepartum period were investigated using 30 cows (Ward, LA). One half of the cows were housed under fans and sprinklers and the other half only had access to shade. Cooling had no effect on body temperature or DMI prior to calving and had no effect on milk production after calving. However, cooling prior to calving decreased DMI after calving.
B. Effect of environmental stressors on reproductive performance.
Accomplishment: Progress in characterizing components of the oocyte altered by elevated temperature has been made (Edwards, TN). Heat shock did not alter nuclear maturation as culture at 41ºC for up to 24 h and did not alter progression of the oocyte to metaphase. Heat shock did not alter membrane integrity as culture at 41ºC for up to 24 h, did not alter proportion of oocytes recovered, lysed, or having an intact membrane after cumulus denudement. Heat shock did alter a number of components within the egg cytoplasm. Cortical granule types were altered after heat shock suggesting possible alterations in the cytoskeleton. Glutathione content was elevated in the oocyte after heat shock suggesting possible increases in free radicals. Retinol improved the development of oocytes compromised by heat stress.
C. Effect of genetic selection on heat tolerance or intolerance.
Accomplishment: Days open (DO) records from GA, TN and NC were analyzed accounting for heat stress via a norm-reaction model (Misztal, GA). The shape of the heat index for DO was close to sinusoidal with the highest value in April and the lowest value in October. Genetic and residual variances and heritabilities were highest for spring calvings and lowest for fall calvings. The variance associated with the highest level of heat index was 33% of the genetic variance under no heat stress. Genetic correlation between regular and heat stress effects was 0.67.
Studies have addressed the interaction between coat color (black versus white percentage) and heat stress on thermal heat load in dairy cattle (Godfrey - USVI). Pictures of cows on heat stress trials during the summer of 2003 (Willard, MS) have been acquired, and will be analyzed in cooperation with Godfrey - USVI and included as a parameter in study analysis and future experimental designs. These studies thus far have identified advantages in dairy cattle with a greater percentage of white hair-coat relative to their thermal tolerance.
A survey of genotypes expressing increased tolerance to heat shock at the cellular level is underway (Hansen - FL). In cooperation with this aim, the production performance and genotypic differences in Gir (Bos indicus) x Holstein and Holstein cattle are being evaluated (Willard-MS). Cross-bred heifers and bulls have reached one-year of age as of this progress report, and growth curves are being analyzed relative to Holstein companions. Gir x Holstein heifers are currently being added to the breeding herd for artificial insemination to Holstein sires, and crossbred bulls are being ejaculated to assess timing of puberty and ejaculate quality.
D. Effect of heat stress and production level on endocrine profiles.
Accomplishment: The concentrations of metabolites and hormones during the 12 weeks after calving in dairy cows calving in either summer (August) or winter (January) were compared (Whisnant - NC). Serum P4 concentrations increased earlier in winter indicating an earlier first ovulation. Levels of non-esterified fatty acids and beta hydroxy butyrate were higher and cholesterol was lower in summer cows. These may indicate that summer cows were in a poorer nutritional state than winter cows. Serum leptin concentrations were higher in summer cows, which may reflect photoperiod differences. Concentrations of glucose, insulin and plasma urea nitrogen (PUN) and thyroxine (T4) did not differ between seasons. Thyroxine and PUN levels increased gradually over time in both groups.
Objective II:
A. Effect of nutritional strategies to enhance intake and efficiency of nutrient utilization and improve reproduction in hot, humid climates.
Accomplishment: The effect of feeding a fibrolytic enzyme or yeast on production and energy sttus of lactating Holsteins was investigated (Smith, Willard, MS; Ward, LA) Dietary treatments were: 1) fibrolytic enzyme (7g/d in LA; 15 g/d in MS), 2) 113 g/d yeast or 3) controls. In LA, dietary treatment had no effect on DMI, milk production, milk composition, or blood NEFA or glucose concentrations. In MS, cows supplemented with yeast and Fibrozyme averaged 4.2% and 9.3% greater feed intake than controls and during the final 3 weeks of the study, the difference in feed intake became more pronounced for cows supplemented with Fibrozyme; in this period their intake averaged 15% greater than controls. The dietary supplements used had no impact on cow body temperatures or respiration rates.
Accomplishment: Trials investigated the relationship between DCAD (25 or 50 meq Na+K-Cl/100 g DM) and dietary crude protein (CP) concentrations (14.5 or 16.8% CP) and the relationship between DCAD (25 or 50 meq/100 g DM) and protein degradability (15% CP with either 33 or 42% of CP as undegradeable intake protein (UIP)(West, Bernard, GA). Increasing DCAD improved DMI and yield of milk, fat, protein. Blood bicarbonate was higher and urinary N was lower for the high DCAD. An interaction was observed between DCAD and UIP for DMI and yield of milk, fat, and protein because of improved intake and yield for high DCAD at 33% UIP where intake and yield were similar for both DCAD concentrations at 42% UIP. Urinary urea N excretion was greater for low DCAD and for 33 versus 42% UIP.
B. Effect of hormonal supplements to enhance reproductive performance in hot, humid climates.
Accomplishment: Studies have been conducted (Godfrey-USVI; Whisnant-NC; Willard-MS) to evaluate supplemental GnRH administration post-breeding on endocrine profiles and pregnancy rates in heat stressed dairy cows and heifers. Results have been variable among location with respect to pregnancy rates and further analysis is continuing.
Accomplishment: Administration of GnRH to heat stressed dairy cows on either day 5, or day 5 and 11 after insemination to a timed AI in heat stressed dairy cows was tested (Whisnant-NC). A similar treatment was performed in winter for comparison. During summer, the temperature-humidity index (THI) values averaged 76.0, which is considered mild heat stress. Serum P4 was increased by GnRH administration in both groups. Pregnancy rates were higher in the cows receiving GnRH on both days 5 and 11 (35.7-2.4%) than in controls (14.5-1.5%) and in cows receiving GnRH on day 5 only (22.8-5.5%). In winter, GnRH administration increased serum P4 concentrations but had no effect on pregnancy rates. Pregnancy rates were 25% in both controls and the day 5 group and 33% for the day 5 and 11 group. Although not a planned comparison, serum P4 concentrations were higher in control (no supplemental GnRH) cows in winter than in control cows sampled during the summer. This seasonal difference was also seen in other treatment groups, confirming earlier reports of lower P4 in cows under heat stress conditions.
C. Effect of environmental modifications on lactational and reproductive performance in hot, humid climates.
Accomplishment: To characterize the impact of tunnel ventilation cooling on lactation performance during periods of hot weather (Smith, Willard-MS). A 10-week trial, which began June 2, 2003, compared two groups of 10 cows housed in the tunnel ventilation barn with two similar groups, housed in an adjacent traditional freestall barn, cooled by shade and fans alone. Tunnel ventilation cooling decreased exposure to moderate heat stress conditions by 4.3 hours/d when compared to conditions in the traditional freestall barns. Cows housed in the tunnel barn had dramatically lower peak body temperatures (1.2 OF) and respiration rates (15.7 breaths/min) than cows housed in the outside freestall barn. Cooling improved feed consumption an average of 4.0 lbs/hd/d. In addition, cows receiving the tunnel ventilation cooling averaged 5.9 lbs/hd/d greater milk production than cows cooled with shade and fans alone.
Cows housed in a tunnel ventilation barn were compared for reproductive performance with a similar group of cows housed in an adjacent traditional freestall barn, cooled by shade and fans alone (Smith, Willard-MS). Cows were synchronized using 2-injections of PGF2a over 14 d, and observed continuously for signs of estrous activity. The average duration of estrus was shorter for cows in the tunnel barn than for those housed outside 6.78+0.87 h vs. 10.33+3.24 h, respectively. Cows in the tunnel barn tended to exhibit signs of estrus earlier in the day than cows housed outside. The pregnancy rate was 37.5% for cows housed in tunnel barn and 25% for cows housed outside.
The use of fans only and fans plus sprinklers was explored to evaluate animal production in relation to size of cow (Large or Small); Willard,MS). The cows were housed in a free stall barn. Rectal temperatures, dorsal and ventral infrared temperature (DIR and VIR) and ventral infrared temperature (DIR and VIR) and respiratory rates did not differ in relation to size of the cow. However, the cows in the fan and sprinkler groups had lower rectal temperature, VIR, DIR, and respiratory rate than the cows in the fan only group. Milk production followed the same pattern with size of the cow having no affect, but the groups that were cooled with the fan and sprinkler produced more milk throughout the trial. Daily income per cow was greatest for the small animals cooled by fan and sprinkler followed by the larger animals cooled with fan and sprinkler, the small cows cooled by fans, and then the large animals cooled by fans. In addition when the economics of the cooling systems and DMI were calculated, daily income per cow was greatest for the small cow fan and sprinkler group.
Impacts
- Coat color did not appear to have a strong influence on the response of dairy cows to elevated environmental temperatures as measured by either subcutaneous or vaginal temperatures. The higher rectal temperatures found in dark heifers suggests that selection for white coat color may be useful in mitigating the effects of heat stress in dairy cattle in hot climates.
- Sprinkling cows resulted in lower afternoon body temperatures of cows and heifers and improved milk yield.
- Cows preferred the full Sand Trap compared to the one-half device. Sand was superior to rice hulls as a bedding material because sand remained in stalls and had lower bacterial counts than rice hull bedding.
- Gaining a further understanding of the effects of elevated temperature at the cellular and molecular level of the oocyte is a necessary first step toward developing novel strategies aimed at mitigating the negative effect of heat stress for improving reproduction related to oocyte quality.
- The norm reaction model for DO allows inexpensive albeit limited genetic evaluation for fertility under heat stress.
- The identification of the specific genes involved in thermotolerance among breeds could lead to novel ways to increase resistance of cattle to heat stress.
- Seasonal differences in reproductive hormones and blood metabolites indicate that cows in hot weather exhibited differences in the reproductive cycle, which may reflect effects due to nutritional status. Determining these seasonal effects and the causative factors is necessary to develop procedures to improve reproductive performance.
- Nutritional modification with yeast and/or Fibrozyme may help to increase feed intake and partially overcome the effects of appetite depression associated with heat stress.
- A relationship between DCAD and protein nutrition appears to exist. Increasing dietary DCAD to 50 meq/100 g DM improved feed intake and yield of milk and decreased urinary urea N excretion. A better understanding of this relationship will result in the ability to supply the protein needs of the lactating cow in a more efficient manner.
- Should treatment with GnRH post-breeding prove effective for improving fertility in heat-stressed dairy cows, this practice could be easily implemented by producers at very low cost (less than $5 per cow). Nevertheless, the variable nature of the responses observed to date may preclude its use by producers.
- Use of a hormonal supplement improved pregnancy rates of heat stressed dairy cows. The effect occurred in hot weather but not during cool weather, indicating that hormonal therapies may be used to enhance reproductive performance in hot climates.
- Tunnel ventilation cooling can be used to mitigate the effects of heat stress on lactating dairy cattle in the southeastern US.
- Understanding the basic biology of heat stress in dairy cows is crucial to overcoming its effects. This research contributes to that basic research, and also works to identify management strategies to mitigate the impact of heat stress on dairy reproduction.
- Holstein cattle have been selected for increased body size in North America for many years. Cooling efficiency based on cow size may assist producers in selecting animals that will most efficiently cool themselves during periods of heat stress. This may result in a net increase in daily income per cow through more efficient cooling via decreased overhead costs by selecting for cow body types that may cool more effectively.
Publications
Edwards J.L., W.A. King, S.J. Kawarsky and A.D. Ealy. 2001. Responsiveness of early embryos to environmental insults: Potential protective roles of HSP70 and glutathione. Theriogenology 55(1):209-224.
Lawrence J.L., R.R. Payton, J.D. Godkin, A.M. Saxton, F.N. Schrick and J.L. Edwards. 2004. Retinol improves development of bovine oocytes compromised by heat stress during maturation. J. Dairy Sci. (In press).
Nobre, P. R. C. , I. Misztal , S. Tsuruta, J. K. Bertrand, L. O. C. Silva, and P. S. Lopes. 2003. Analyses of Growth Curves of Nelore Cattle by Multiple Trait and Random Regression Models. J Anim. Sci. 81:918-926.
Oseni, S., I. Misztal, S. Tsuruta, and R. Rekaya. 2003. Seasonality of Days Open in US Holsteins. J. Dairy Sci. 86:3718-3725.
Van Tassell, C. P., G. R. Wiggans, and I. Misztal. 2003. Implementation of a Sire-Maternal Grandsire Model for Evaluation of Calving Ease in the United States. J. Dairy Sci. 86: 3366-3373.
West, J. W., B. G. Mullinix, and J. K. Bernard. 2003. Effects of hot, humid weather on body temperature, dry matter intake, and milk yield of lactating dairy cows. J. Dairy Sci. 86:232-242.
Wiggans, G. R., I. Misztal, and C. P. Van Tassell. 2003. Calving Ease (Co)Variance Components for a Sire-Maternal Grandsire Threshold Model. J. Dairy Sci. 86:1845-1848.
Willard, S., S. Gandy, S. Bowers, K. Graves, A. Elias and C. Whisnant. 2003. The effects of GnRH administration post-breeding on serum concentrations of progesterone and pregnancy rates in dairy cattle exposed to mild summer heat stress. Theriogenology 59(8): 1799-1810.
Meeting Abstracts and Experiment Station Reports:
Bohmanova, J., I. Misztal, and J. Pribyl. 2003. Differences in growth trajectories in seven beef breeds. J. Anim. Sci. (Suppl.) 81:198.
Dickerson, T., K. Graves, J. White, S. Bowers, L. Evans, B. Gandy, S. Schmidt and S. Willard. 2003. The effects of supplemental GnRH administration following OvSynch on pregnancy rates of lactating dairy cattle during the summer and fall seasons. J. Dairy Science 86 (Suppl. 1): 179 (Abstr. M4; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Dorado, C.M., L.M. McCann, J.A. Miller and J.L. Edwards. 2001. Nuclear status of bovine oocytes exposed to elevated temperature after resumption of meiosis. Theriogenology 55(1):469.
Evans, H.L., R.C. Vann, J. Murphy, E.J. Cuadra and S.T. Willard. 2003. The effect of cooling strategy during summer heat stress on production performance and body composition quality traits in lactating Holstein dairy cattle. 2002 Central Mississippi R & E Progress Report.
Evans, H., J. Murphey, E. Cuadra, T. Dickerson, S. Gandy, S. Willard and R. Vann. 2003. The effects of cooling strategy and level of milk production on milk constituents and body composition quality traits during summer heat stress in lactating Holstein dairy cattle. J. Dairy Science 86 (Suppl. 1): 281 (Abstr. T181; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Evans, H.L., J. Murphy, E. Cuadra, S.T. Willard and R.C. Vann. 2003. The effect of cooling strategy during summer heat stress on production performance and body composition quality traits in lactating Holstein dairy cattle. ASAS Southern Section Meetings, Mobile, AL January 31 ? 4, 2003; Abstract 57, pg. 15.
Godfrey, R.W., Isles, O.T., Weis, A.J. and R.E. Dodson. 2003. The effect of hair coat color on rectal and surface temperatures of Holstein heifers in the tropics. J. Anim. Sci. 81(Suppl. 1):145.
Godfrey, R.W., Dodson, R.E., Weis, A.J. and O.T. Isles. 2003. The effect of using Ovsynch with supplemental GnRH on pregnancy rates of Holstein heifers in the tropics. J. Anim. Sci. 81(Suppl. 1):145.
Lawrence J.L., R.R. Payton, J.D. Godkin, A.M. Saxton, F.N. Schrick, J.L. Edwards. 2003. Development of heat-stressed oocytes matured in the presence of retinol. Biol. Reprod. 68(1):344.
Legarra, A., I. Misztal1, and J. Jamrozik. 2003. Plotting covariance functions from random regression models. J. Dairy Sci (Suppl. 1) 86:114.
Misztal, I., S. Oseni, and S. Tsuruta. 2003. Analyses of heat tolerance for milk in Holsteins using different sources of heat-stress information. J. Dairy Sci (Suppl. 1) 86:39.
Nordbladh, LI, AE Sweetman, CS Whisnant. 2003. Postpartum changes in hormones and metabolites during early lactation in summer and winter calving Holstein cows. J. Anim Sci. 81: Suppl.1, p 298.
Oseni, S., and I. Misztal. 2003. Seasonality of days open in US Holsteins. J. Dairy Sci (Suppl. 1) 86: 131.
Panivivat, R., Pennington, J.A., Kegley, E.B., Kellogg, D.W., and Krumpelman, S.L. 2003. Growth performance and health of dairy calves bedded with different types of materials. J. Dairy Sci. 86(Suppl.1):280.
Panivivat, R., Kegley, E.B., Kellogg, D.W., Pennington, J.A. VanDeveder, K., Hellwig, D.H., Wistuba, T.J., and Krumpleman S.L. 2003. Growth performance and health of dairy calves bedded with different types of materials. University of Arkansas Agric. Exp. Sta. Res. Series 509. Pages 83-87.
Payton R.R., P. Coy, R.R., A.M. Saxton, J.L. Lawrence, J.L. Edwards. 2003. Heat stress reduces development of germinal vesicle-stage bovine oocytes. Biol. Reprod. 68(1):343.
Payton, R.R., P. Coy, R. Romar, J.L. Lawrence, J.L. Edwards. 2003. Heat shock increases glutathione content in bovine oocytes. J. Anim. Sci. 86(1):3.
Payton R.R., J.L. Lawrence, A.M. Saxton, J.R. Dunlap, and J.L. Edwards. 2003. Cortical granule types and nuclear stage of bovine oocytes after exposure to elevated temperature during maturation. Theriogenology 59(1):496.
Sapp, R. L., R. Rekaya, J. K. Bertrand, I. Misztal, and K. A. Donoghue. 2003. Genetic parameter estimates of udder scores in Gelbvieh cattle. J. Anim. Sci. (Suppl.) 81:88.
Schmidt, S.J., B.S. Gandy, F. Hoholm, K. Graves, J. White, S.T. Willard. 2003. Physiology of pregnancy and calving characteristics of Holstein cows bred to Holstein or Gir (Bos indicus) sires. J. Dairy Science 86 (Suppl. 1): 143 (Abstr. 567; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Smith, T.R., A. Chapa, D. Pogue, T. Riley, J. Williams, J. Crouch and Heather Wilson. 2004. Tunnel ventilation cooling for lactating dairy cows during hot weather: 2. Comparison to cooling with shade and fans. Annual Report 2003 of the North Mississippi Research & Extension Center, Mississippi Agriculture & Forestry Experiment Station Information Bulletin.
Sweetman, AE, LI Norbladh, CS Whisnant. 2003. Effect of administration of GnRH on day 5 or day 5 and 11 post-insemination on pregnancy rates and serum progesterone concentrations in dairy cows during different seasons. J. Anim Sci. 81: Suppl.1, p 178.
Tsuruta, S., I. Misztal, and T. Druet. 2003. Comparison of estimation methods for heterogeneous residual variances with random regression models. J. Dairy Sci (Suppl. 1) 86:113.
Wildman , C. D., J. W. West, and J. K. Bernard. 2003. Effect of dietary cation-anion difference and crude protein content on milk yield and blood metabolites of lactating dairy cows during hot weather. J. Dairy Sci. 86 (Suppl. 1):216. (Abstr.)
Williams, R.J., A.M. Chapa, T.O. Riley, D.O. Pouge, S.T. Willard and T.R. Smith. 2003. The impact of tunnel ventilation cooling and brown mid-rib (BMR) corn silage on heat stress in lactating dairy cows. J. Dairy Science 86 (Suppl. 1): 249 (Abstr. T53; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Williams, R. Justin, Angelica M. Chapa, Thad O. Riley, Donald E. Pogue, Scott T. Willard and Terry R. Smith. 2004. The impact of tunnel ventilation cooling and BMR corn silage on heat stress in lactating dairy cows. J. Dairy Sci 86 (Suppl 1): Abstr.
Lawrence J.L., R.R. Payton, J.D. Godkin, A.M. Saxton, F.N. Schrick and J.L. Edwards. 2004. Retinol improves development of bovine oocytes compromised by heat stress during maturation. J. Dairy Sci. (In press).
Nobre, P. R. C. , I. Misztal , S. Tsuruta, J. K. Bertrand, L. O. C. Silva, and P. S. Lopes. 2003. Analyses of Growth Curves of Nelore Cattle by Multiple Trait and Random Regression Models. J Anim. Sci. 81:918-926.
Oseni, S., I. Misztal, S. Tsuruta, and R. Rekaya. 2003. Seasonality of Days Open in US Holsteins. J. Dairy Sci. 86:3718-3725.
Van Tassell, C. P., G. R. Wiggans, and I. Misztal. 2003. Implementation of a Sire-Maternal Grandsire Model for Evaluation of Calving Ease in the United States. J. Dairy Sci. 86: 3366-3373.
West, J. W., B. G. Mullinix, and J. K. Bernard. 2003. Effects of hot, humid weather on body temperature, dry matter intake, and milk yield of lactating dairy cows. J. Dairy Sci. 86:232-242.
Wiggans, G. R., I. Misztal, and C. P. Van Tassell. 2003. Calving Ease (Co)Variance Components for a Sire-Maternal Grandsire Threshold Model. J. Dairy Sci. 86:1845-1848.
Willard, S., S. Gandy, S. Bowers, K. Graves, A. Elias and C. Whisnant. 2003. The effects of GnRH administration post-breeding on serum concentrations of progesterone and pregnancy rates in dairy cattle exposed to mild summer heat stress. Theriogenology 59(8): 1799-1810.
Meeting Abstracts and Experiment Station Reports:
Bohmanova, J., I. Misztal, and J. Pribyl. 2003. Differences in growth trajectories in seven beef breeds. J. Anim. Sci. (Suppl.) 81:198.
Dickerson, T., K. Graves, J. White, S. Bowers, L. Evans, B. Gandy, S. Schmidt and S. Willard. 2003. The effects of supplemental GnRH administration following OvSynch on pregnancy rates of lactating dairy cattle during the summer and fall seasons. J. Dairy Science 86 (Suppl. 1): 179 (Abstr. M4; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Dorado, C.M., L.M. McCann, J.A. Miller and J.L. Edwards. 2001. Nuclear status of bovine oocytes exposed to elevated temperature after resumption of meiosis. Theriogenology 55(1):469.
Evans, H.L., R.C. Vann, J. Murphy, E.J. Cuadra and S.T. Willard. 2003. The effect of cooling strategy during summer heat stress on production performance and body composition quality traits in lactating Holstein dairy cattle. 2002 Central Mississippi R & E Progress Report.
Evans, H., J. Murphey, E. Cuadra, T. Dickerson, S. Gandy, S. Willard and R. Vann. 2003. The effects of cooling strategy and level of milk production on milk constituents and body composition quality traits during summer heat stress in lactating Holstein dairy cattle. J. Dairy Science 86 (Suppl. 1): 281 (Abstr. T181; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Evans, H.L., J. Murphy, E. Cuadra, S.T. Willard and R.C. Vann. 2003. The effect of cooling strategy during summer heat stress on production performance and body composition quality traits in lactating Holstein dairy cattle. ASAS Southern Section Meetings, Mobile, AL January 31 ? 4, 2003; Abstract 57, pg. 15.
Godfrey, R.W., Isles, O.T., Weis, A.J. and R.E. Dodson. 2003. The effect of hair coat color on rectal and surface temperatures of Holstein heifers in the tropics. J. Anim. Sci. 81(Suppl. 1):145.
Godfrey, R.W., Dodson, R.E., Weis, A.J. and O.T. Isles. 2003. The effect of using Ovsynch with supplemental GnRH on pregnancy rates of Holstein heifers in the tropics. J. Anim. Sci. 81(Suppl. 1):145.
Lawrence J.L., R.R. Payton, J.D. Godkin, A.M. Saxton, F.N. Schrick, J.L. Edwards. 2003. Development of heat-stressed oocytes matured in the presence of retinol. Biol. Reprod. 68(1):344.
Legarra, A., I. Misztal1, and J. Jamrozik. 2003. Plotting covariance functions from random regression models. J. Dairy Sci (Suppl. 1) 86:114.
Misztal, I., S. Oseni, and S. Tsuruta. 2003. Analyses of heat tolerance for milk in Holsteins using different sources of heat-stress information. J. Dairy Sci (Suppl. 1) 86:39.
Nordbladh, LI, AE Sweetman, CS Whisnant. 2003. Postpartum changes in hormones and metabolites during early lactation in summer and winter calving Holstein cows. J. Anim Sci. 81: Suppl.1, p 298.
Oseni, S., and I. Misztal. 2003. Seasonality of days open in US Holsteins. J. Dairy Sci (Suppl. 1) 86: 131.
Panivivat, R., Pennington, J.A., Kegley, E.B., Kellogg, D.W., and Krumpelman, S.L. 2003. Growth performance and health of dairy calves bedded with different types of materials. J. Dairy Sci. 86(Suppl.1):280.
Panivivat, R., Kegley, E.B., Kellogg, D.W., Pennington, J.A. VanDeveder, K., Hellwig, D.H., Wistuba, T.J., and Krumpleman S.L. 2003. Growth performance and health of dairy calves bedded with different types of materials. University of Arkansas Agric. Exp. Sta. Res. Series 509. Pages 83-87.
Payton R.R., P. Coy, R.R., A.M. Saxton, J.L. Lawrence, J.L. Edwards. 2003. Heat stress reduces development of germinal vesicle-stage bovine oocytes. Biol. Reprod. 68(1):343.
Payton, R.R., P. Coy, R. Romar, J.L. Lawrence, J.L. Edwards. 2003. Heat shock increases glutathione content in bovine oocytes. J. Anim. Sci. 86(1):3.
Payton R.R., J.L. Lawrence, A.M. Saxton, J.R. Dunlap, and J.L. Edwards. 2003. Cortical granule types and nuclear stage of bovine oocytes after exposure to elevated temperature during maturation. Theriogenology 59(1):496.
Sapp, R. L., R. Rekaya, J. K. Bertrand, I. Misztal, and K. A. Donoghue. 2003. Genetic parameter estimates of udder scores in Gelbvieh cattle. J. Anim. Sci. (Suppl.) 81:88.
Schmidt, S.J., B.S. Gandy, F. Hoholm, K. Graves, J. White, S.T. Willard. 2003. Physiology of pregnancy and calving characteristics of Holstein cows bred to Holstein or Gir (Bos indicus) sires. J. Dairy Science 86 (Suppl. 1): 143 (Abstr. 567; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Smith, T.R., A. Chapa, D. Pogue, T. Riley, J. Williams, J. Crouch and Heather Wilson. 2004. Tunnel ventilation cooling for lactating dairy cows during hot weather: 2. Comparison to cooling with shade and fans. Annual Report 2003 of the North Mississippi Research & Extension Center, Mississippi Agriculture & Forestry Experiment Station Information Bulletin.
Sweetman, AE, LI Norbladh, CS Whisnant. 2003. Effect of administration of GnRH on day 5 or day 5 and 11 post-insemination on pregnancy rates and serum progesterone concentrations in dairy cows during different seasons. J. Anim Sci. 81: Suppl.1, p 178.
Tsuruta, S., I. Misztal, and T. Druet. 2003. Comparison of estimation methods for heterogeneous residual variances with random regression models. J. Dairy Sci (Suppl. 1) 86:113.
Wildman , C. D., J. W. West, and J. K. Bernard. 2003. Effect of dietary cation-anion difference and crude protein content on milk yield and blood metabolites of lactating dairy cows during hot weather. J. Dairy Sci. 86 (Suppl. 1):216. (Abstr.)
Williams, R.J., A.M. Chapa, T.O. Riley, D.O. Pouge, S.T. Willard and T.R. Smith. 2003. The impact of tunnel ventilation cooling and brown mid-rib (BMR) corn silage on heat stress in lactating dairy cows. J. Dairy Science 86 (Suppl. 1): 249 (Abstr. T53; ASAS/ADSA 2003 National Meeting, Phoenix, AZ).
Williams, R. Justin, Angelica M. Chapa, Thad O. Riley, Donald E. Pogue, Scott T. Willard and Terry R. Smith. 2004. The impact of tunnel ventilation cooling and BMR corn silage on heat stress in lactating dairy cows. J. Dairy Sci 86 (Suppl 1): Abstr.