Brief Summary of Minutes of Annual Meeting

The S-1023 Regional Meeting was called to order by the Chair, Scott Willard (MS), at 8:15 a.m. on February 4th. Self-introductions of all participants ensued followed by station reports (in the order they were presented) from R. Godfrey (USVI), S. Willard (MS), J. West (GA), J. Bernard (GA), and I. Misztal (GA). After a break for lunch station reports resumed as follows (in the order they were presented) from T. Smith / X. Wang (MS), J. Pantoja (PR) and L. Edwards (TN). At 3:20 p.m. Dr. D. Morrison (Administrative Advisor) made comments regarding the renewal of the project and thanked T. Smith (MS) and S. Willard (MS) for their contributions in writing/editing the document and all S-1023 participants that submitted information for the renewal document for their efforts. Dr. Morrison then referred the group to the e-mail and information provided by D. Hamernik (USDA-CSREES) prior to the meeting on federal USDA-NRI budgets and granting opportunities. The Business Meeting was then initiated and resulted in the following: (1) Election of Officers  After nominations it was decided that R. Godfrey (USVI) would serve as Chair-Elect and J. Bernard (GA) as incoming Secretary. L. Edwards (TN) will serve as Chair of the next meeting. (2) Meeting Location for 2007  It was decided that Mobile, AL would serve as the tentative next meeting site along with the SAAS meeting. (3) Protocols  R. Godfrey (USVI) indicated that if members have common use or sampling protocols that need to be posted on the S-1023 website that they should e-mail these materials to him. (4) Station Reports  S. Willard (Chair; MS) requested that station reports by submitted to him via e-mail by March 1st so that the annual report and minutes could be compiled and sent to D. Morrison by April 1st in accordance with SAAESD guidelines. (5) Collaborations - Discussion centered on collaborative granting efforts including an interest by the group in an integrated research/extension grant on prepartum cooling and prepartum indicators of postpartum reproductive/production performance. Discussions of a group paper or technical report on comparative methods for monitoring body temperature by the techniques used by the participants ensued, with interest by the group to work on the development of such a project.

Note that the principal reporting station is indicated in relation to the stated accomplishment and subsequent impact, but may involve more than one investigator from that station. Multi-state collaborative projects are indicated within the Accomplishments under each sub-objective and are further reflected in the List of Publications and Plans for the Coming Year sections that follow the Accomplishments and Impacts. Objective 1. Defining the physiological characteristics of heat-stressed dairy cattle 1A. Quantifying heat stress in dairy cattle. Accomplishment: Current research is defining the physiological characteristics of heat stress in dairy cattle, with specific emphasis on the relationships between secondary cow characteristics (coat color and density; see also sub-objective 1E below) in relation to their ability to tolerate heat stress (PR). Preliminary study designs consist of rectal temperatures taken daily at various intervals along with vaginal temperatures taken with HOBOs mounted on intravaginal CIDR devices for seven consecutive days for comparisons of dairy cows (n = 17) that differ in hair coat density. The partial correlation between rectal and vaginal was 0.66 (P < 0.01). It was noted that there was more variation in rectal than in vaginal temperatures taken with the HOBO data loggers. Partial correlation coefficients between rectal temperatures and respiration rates were 0.50 (P < 0.01). These data will be compared in the future with rectal temperature:vaginal HOBO data acquired at other collaborating stations (GA, MS and USVI). Accomplishment: Digital infrared thermography (DITI) is being examined as a tool for evaluating the effects of climatic influences (i.e., heat stress) on cows in relation to black vs. white hair coat in a typical freestall environment and in relation to cooling strategies. Genetic effects are being further evaluated using DITI among Holstein, Jersey and Gir x Holstein cows. Results suggest that cow body surface temperatures are highly influenced by environmental conditions, which DITI can detect, including differences in responsiveness among breeds. These data establish relationships between cow body surface thermal signatures within production environments from which further studies can assess the use of DITI for the environmental monitoring of dairy cattle. DITI is also being used to evaluate environmental effects (cooling and ambient conditions) on the use of this tool for the detection of reproductive status. The current data suggest a tendency for right-side DITI as a better predictor of pregnancy than left-side DITI in Holstein heifers. However, the ability to truly discriminate pregnant from non-pregnant heifers remains questionable (as affected by: ambient temperature, hair coat condition or patterns, etc.). At the ambient temperatures when measures were acquired, thermography revealed no temperature difference between estrus and early diestrus in cycling cows, and the ability to discriminate between estrus and diestrus was greatly influenced by ambient temperature. Accomplishment: Studies are addressing the effects of heat stress on the bovine oocyte (TN). Current results provide strong supportive evidence that physiologically relevant elevated temperatures induce premature aging of the bovine oocyte, thereby reducing fertile lifespan. Specifically, we observed that direct exposure of bovine oocytes to an elevated temperature commonly seen in heat-stressed dairy cows hastened in vitro maturation (i.e., heat-stressed oocytes mature faster than controls). Moreover, earlier insemination in vitro prevented heat-induced reductions in oocyte development compared to controls 1B. The effect of various summer cooling strategies on symptoms of heat stress, endocrine status and lactation performance. Accomplishment: Data were collected from a trial designed to compare the effectiveness of high-speed fans (HS, 36 inch, 0.5 hp) with low-speed fans (LS, 20 ft., 1.0 hp; GA). Both fan systems are installed in a four-row free stall barn (100 ft wide x 440 ft long) with a drive through feed alley. Four rows of HS are installed ever 20 ft over the feed alley and free stalls. Four high pressure mister nozzles (~250 psi) are mounted to the face of each fan. The system is designed to operate automatically when the temperature exceeds 75 F. The high pressure misters automatically cut off when the relative humidity (RH) exceeds 85%. The LS are mounted in the center of the barn 60 ft centers. Individual core body temperatures (CBT) were recorded intravaginally using the HOBO Water Temp Pro. Treatments were switched each day at 0900 h in the randomized design trial and replicated across two years. Air flow measured at various locations in the free stall barn ranged from 2.5 to 5.0 mph for LS compared with 5.0 to 8.0 for HS. Air flow for areas not directly in line with HS dropped to 0 to 2 mph. Although the LS provided a more even airflow throughout the barn, the flow rates produced by this model of fan in this barn were considered lower than desired in the most critical areas. The 1030 CBT was used as a covariate in the statistical analysis. In both 2004 and 2005, CBT was higher for cows cooled with LS compared with HS. Mean CBT for HS and LS were 102.88 and 103.22 F in 2004 (SE = 0.08, P = 0.05) and 102.58 and 102.95 F in 2005 (SE = 0.09, P = 0.009). No interaction of treatment and time was observed in 2004, but an interaction was observed during 2005 (P < 0.0001) because differences in CBT between systems were greater from 1430 through 1800 compared with all other times except from 0600 through 0800 when CBT was lower with LS compared with HS. The LS fans were not turned off each 24 h period which may account for the lower CBT observed during the morning compared with HS which automatically turned off when the ambient temperature was less than 75 F. These results indicate that LS do not provide adequate airflow to cool lactating dairy cows as effectively as HS. 1C. Characterize the impact of prepartum cooling and identifying prepartum metabolic and endocrine markers as indicators of postpartum performance. Accomplishment: While work has not begun on this sub-objective, planning for a proposed collaborative project among several of the participating stations (GA, MS and NC) is underway. The goal is to identify prepartum cooling practices that will result in improved cow health and performance and possibly benefit the calf as well. Fans, sprinklers and other technologies will be used with dry cows and body temperatures, metabolic and endocrine parameters such as non-esterified fatty acids, plasma urea nitrogen, beta-hydroxybutyrate, insulin and thyroid hormones will be measured (linked to sub-objective 2B below). Production data, days to first ovulation and days to pregnancy will be recorded for cows and birth weight and growth measurements will be recorded for calves. An additional sub-objective may be formulated to address specifically calf performance and physiology in relation to dam treatments during the prepartum period. 1D. Characterize the effect of genetic selection in heat tolerance. Accomplishment: Heat stress was evaluated as a factor in the genotype x environment interaction in the United States for milk (GA). The national data set (NA) consisted of 56 million first-parity test day milk yields on 6 million Holsteins. The Northeastern subset (NE) included 12.5 million records on 1.3 million cows from eight states, and the Southeastern subset (SE) included 3.5 million records on 0.4 million cows from eleven states. Climatic data was available from 202 public weather stations. Correlations involved breeding values from SE and NE for sires > 300 daughters in each region. When heat stress was ignored (first model) the correlations of mild-climate PTA of sires were 0.86. When heat stress was considered in the model, the correlation increased by 0.01. The correlations of heat stress PTA between NE and SE daughters was 0.71. They increased to 0.81 for sires with > 700 daughters. Evaluations for heat tolerance are similar in cooler and hotter regions for high reliability sires. Accomplishment: A long-term goal is to identify genes controlling cellular thermotolerance and transfer these genes into Holstein cattle to reduce the magnitude of deleterious effects of elevated temperature on embryonic survival, immune function, and other aspects of physiological function in cattle. In cooperation with this aim, the production performance and genotypic differences in Gir (Bos indicus) x Holstein and Holstein cattle are being evaluated (MS). A comparison of reproductive parameters in Holstein vs. Gir X Holstein dairy cattle. Study results suggest that Gir X Holstein (G x H) heifers exhibited greater days to first estrus and days to conception, and were heavier at conception than Holstein heifers. Holstein heifers displayed greater mount frequency than G X H heifers, while no differences were observed in duration of estrus and mount duration. No difference in scrotal circumference or testosterone concentrations at 12 months between G X H and H ´ H bulls. G X H bulls also had greater scrotal circumference and testosterone than Holstein bulls at 18 months, yet ejaculate characteristics did not differ between G X H and Holstein bulls at 12 or 18 months, and G X H and Holstein bulls exhibited similar patterns of peripubertal growth (i.e., through 18 months of age). 1E. Determining the relationships between coat color and cow body size on production performance in heat stressed dairy cattle. Accomplishment: Studies conducted previously addressed the interaction between coat color (black versus white percentage) and heat stress on thermal heat load in dairy cattle (USVI). Pictures of cows on heat stress trials from 2004-2005 have been acquired (MS; PR), and will be analyzed in cooperation with USVI and included as a parameter in study analysis and future experimental designs. Standard measures of cow body size are also being developed (MS) for inclusion in study designs by other participating stations as an additional factor for post-study analysis. Objective 2. Improving fertility of heat-stressed dairy cows without decreasing milk production 2A. Use of supplemental hormone administration pre and post breeding to improve fertility of heat stressed dairy cattle. Accomplishment: The goal is to determine if CIDR can be used to enhance pregnancy rates in cows during heat stress periods. In one study conducted at NC, cows bred at a synchronized estrus were assigned to either Control (no CIDR) or Treatment (CIDR) beginning at day 5 after AI. Pregnancy rates to the synchronized breeding and to the subsequent breeding in those cows that showed estrus were recorded. There was no difference in pregnancy rate at the synchronized breeding but CIDR treated cows tended to have a higher pregnancy rate to the breeding at the subsequent estrus. In a companion study conducted at MS, the effects of supplemental progesterone administration on pregnancy rate and resynchronization in lactating dairy cattle during mild heat stress and nonheat stress conditions. Studies were conducted to assess the use of the CIDR as a supplemental P4 source during conditions of mild heat stress and nonheat stress in lactating dairy cows. Cows were synchronized for 7 d using CIDR with administration of PGF on d 6. Following CIDR withdrawal cows detected in estrus were bred by AI, with a timed insemination 54 h after PGF2± for all cows not detected in estrus. Cows were balanced for production variables and assigned as Control (CON; no supplemental CIDR) or CIDR+, which received a second CIDR 11 d after the timedAI. Summer study: Cows were managed under mild heat stress conditions. Ultrasonography at d 42 following the first AI postCIDR revealed a pregnancy rate (PR) of 27% for CIDR+, and 5% for CON. Ultrasonography at d 65, combining first AI and resynchronized AI, revealed an overall PR of 45% for CIDR+, and 18% for CON. Fall study: Cows were managed under cool season conditions. Ultrasonography at d 42 following the first AI postCIDR revealed a PR of 31% for CIDR+, 31% for CON. Ultrasonography at d 65, combining first AI and resynchronized AI, revealed an overall PR of 44% for CIDR+ and 41% for CON. In summary, the use of the CIDR as a supplemental source of P4 postbreeding increased pregnancy rate and accelerated rebreeding under mild heat stress conditions but not during the cool season in lactating dairy cows. Accomplishment: One strategy for improving fertility in cattle is mid-cycle administration of GnRH to increase progesterone secretion and delay luteolysis. This strategy might be especially useful during hot weather because heat stress increases uterine prostaglandin release and reduces development of the elongating embryo. A series of experiments were conducted at FL to test the efficacy of GnRH for increasing fertility. There was no effect of administration of 100 ¼g GnRH at Day 11 after anticipated ovulation on pregnancy rates in virgin heifers subjected to timed artificial insemination (TAI) during the summer. Similarly, there was no beneficial effect of administration of GnRH at Day 11 after anticipated ovulation on pregnancy rates of lactating cows subjected to TAI in summer and winter. Three experiments tested effects of injection of GnRH at Day 14 or 15 after anticipated ovulation on pregnancy rates of lactating cows. The first experiment used 477 lactating cows subjected to TAI. Cows receiving GnRH at Day 14 had higher pregnancy rates in both summer and winter than cows receiving vehicle (20.3% vs 12.7%; P<0.02). When this experiment was repeated during summer with 137 cows, there was a negative effect of GnRH treatment at Day 14 on pregnancy rate. In the third experiment, lactating cows during summer were inseminated at detected estrus and cows were assigned to treatment with either GnRH or vehicle at Day 14 or 15 after insemination. Pregnancy rates were 25.6% (32/125) for cows receiving vehicle, 20.7% (19/92) for cows receiving GnRH at Day 14, and 20.3% (16/79) for cows receiving GnRH at Day 15. In conclusion, GnRH administration at Day 11 to 15 after anticipated ovulation or estrus did not consistently increase pregnancy rates in either cool or warm seasons 2B. Establishing hormone markers pre breeding as predictors of reproductive success in heat stressed and non heat stressed dairy cows. Accomplishment: While administration of bovine somatotropin (bST) to lactating dairy cows increases milk production, it can also increase body temperature during heat stress and may therefore compromise fertility. However, bST increases secretion of insulin-like growth factor-I (IGF-I) and culture of bovine embryos with IGF-I blocks the reduction in blastocyst development and induction of apoptosis caused by heat shock. A study was performed at FL was to determine effects of bST on reproductive function in lactating dairy cows during heat stress. The experiment was conducted in South Georgia from July to November 2005 using 271 lactating Holstein cows. For first service timed artificial insemination (TAI), cows were presynchronized with two injections of PGF2a given 14 d apart followed by a modified Ovsynch protocol (GnRH given 72 h following PGF2a). Pregnancy was diagnosed using ultrasonography on d 29 and reconfirmed by palpation between d 45-80 post-TAI. Non-pregnant cows were resynchronized with the modified Ovsynch protocol and received TAI. Treatment with bST (500 mg; Posilac, Monsanto) started 1 wk prior to the start of Ovsynch and continued at 2-wk intervals. A subset of cows (n=38) were bled for IGF-I profiles immediately prior to the first bST injection, 1 wk later, and at d 35 of bST treatment. Rectal temperatures were taken on d 29 of bST treatment. Pregnancy rates (d 45-80 post-TAI) did not differ between control (n=129) and bST-treated cows (n=142) for first- (15.5% vs 16.9%) or second-service TAI (17.2% vs 15.0%). Milk yield and plasma concentrations of IGF-I were higher for bST-treated cows following the initiation of bST treatment (bST x time interaction, P<0.01) and bST increased rectal temperature (P<0.05; 39.17°C vs 39.31°C for control vs IGF-I cows, SEM=0.05°C). 2C. Use of interval cooling (i.e., immediately before and after breeding) to improve fertility of problem breeders and heat stressed dairy cows. This sub-objective is not being investigated currently, but may be addressed in future years of this project by collaborating stations or as coupled with other sub-objectives. 2D. Use of targeted vitamin and mineral supplementation in conjunction with estrous synchronization and timed AI to improve fertility in heat stressed dairy cows Accomplishment: The goal is to determine if supplementation with vitamin A and E before breeding at a synchronized estrus will improve pregnancy rates in heat stressed dairy cows (NC) and is being planned currently for implementation of this study. Cows will be treated with an injectable vitamin A and E preparation or carrier two weeks prior to the planed breeding date. Pregnancy rates will be monitored to the synchronized breeding Objective 3. Improving milk production of heat-stressed dairy cows without decreasing fertility 3A. The effect of heat stress on nutritional requirements of high-producing dairy cows. Accomplishment: Heat increment is the rise in digestive and metabolic heat production following a meal, and greater heat production is a liability during hot weather. Dietary ingredients have varying effects on heat production; low digestibility ingredients produce more heat proportional to NEL when compared with higher digestibility ingredients. Fats are used with a relatively high efficiency and have a lower heat increment. The high heat increment diet was formulated using cottonseed hulls, cottonseed meal, and higher forage content; low heat increment was formulated by using less total forage, more whole cottonseed, no cottonseed meal or hulls, and a rumen inert fat (GA). Three treatments were imposed: high heat increment fed ad libitum (HI), low heat increment fed ad libitum (LO), and LO fed restricted (LO-Res) to the same caloric intake as the HI diet. There was no difference between DMI per 100 kg BW for the HI and LO diets, while DMI/BW was lower for the LO-Res diet, as expected. Milk yield per DMI (kg/kg), a measure of efficiency, was greater for both the LO and LO-Res treatments when compared with HI, suggesting a slight improvement in efficiency for low heat increment diets. There were no significant differences in NE milk per NE intake (Mcal/Mcal). Respiratory rate was lowest for the LO-Res diet, probably because of the lower total DMI, because of restricted intake. 3B. The effects of high protein diets on production performance and summer breeding in dairy cows. This sub-objective is not being investigated currently, but may be addressed in future years of this project by collaborating stations or as coupled with other sub-objectives. 3C. The effect of dietary supplements (antioxidants, minerals and probiotics) to enhance nutrient intake and digestibility. This sub-objective is not being investigated currently, but may be addressed in future years of this project by collaborating stations or as coupled with other sub-objectives (See Plans for the Coming Year below). Plans for the Coming Year  Established Collaborations and On-going Projects: " Coat color studies and determination of percentages of black vs. white hair coat. (OBJ 1E; PR, MS, TN with VI-STX Lead) " Enzyme enhancements in diets while grazing southern forages. (OBJ 3C; PR, GA - Lead) " Body temperature and estrous cycle - data mining and/or implementation of a summer study (OBJ 1A - MS, and TN - Lead) " Retrospective data mining for seasonal effects on oocyte. (OBJ 2C; FL, TN - Lead) " Body temperature correlates among different measurement techniques, and the proposed coordination of a regional project review paper on the subject. (OBJ 1A - All stations - prelim e-mail to group: MS - Lead; meet in ASAS-MN) (Suggestion: Southern Cooperative series bulletin) " Prepartum Cooling - metabolic/postpartum/cooling methods will be investigated along with nutrition x reproduction interactions related to prepartum cooling. New sub-objective to be considered: calf physiology/responses to dam prepartum cooling (OBJ 1C - GA, TN, NC, MS - Lead) " Heat tolerant sires (OBJ 1D; GA lead on proposal)  will develop a plan for evaluating this among station and seek collaborators in the future to address the selection of heat tolerant sires.

Bohmanova, J., I. Misztal, and J. K. Bertrand. 2005. Studies on multiple trait and random regression models for genetic evaluation of beef cattle for growth. J. Anim. Sci. 83:62-67. Edwards J.L., J.L. Lawrence, R.R. Payton, J.R. Dunlap, and A.M. Saxton. 2005. Exposure to a physiologically-relevant elevated temperature hastens maturation in bovine oocytes. J. Dairy Sci. 88:4326-4333. Finocchiaro, R., J. B. C. H. M. van Kaam, B. Portolano, and I. Misztal. 2005. Effect of Heat Stress on Production of Mediterranean Dairy Sheep. J. Dairy Sci. 88: 1855-1864 Franco, M., Block, J., Jousan, F.D., de Castro e Paula, L.A., Brad, A., Franco, J.M., Grisel, F., Monson, R.L., Rutledge, J.J., and Hansen, P.J. (2005) Effect of transfer of one or two embryos and administration of gonadotropin releasing hormone on pregnancy rates of heat-stressed dairy cattle . Theriogenology, in press. Franco, M., and Hansen, P.J. (2006) Effects of hyaluronic acid in culture and cytochalasin B treatment before freezing on survival of cryopreserved bovine embryos produced in vitro. In Vitro Cell Dev. Biol. Anim., in press. Garcia-Peniche, T. B., B. G. Cassell, R. E. Pearson and I. Misztal. 2005. Comparisons of Holsteins with Brown Swiss and Jersey Cows on the Same Farm for Age at First Calving and First Calving Interval. J. Dairy Sci. 88:790-796. Iwaisaki, H., S. Tsuruta , I. Misztal , and J. K. Bertrand. 2005. Estimation of Correlation Between Maternal Permanent Environmental Effects of Related Dams in Beef Cattle. J. Anim. Sci. 83:537-542. Iwaisaki, H., S. Tsuruta , I. Misztal , and J. K. Bertrand. 2005. Genetic parameters estimated with multi-trait and linear spline-random regression models using Gelbvieh early growth data. J. Anim. Sci. 83:499-506. Jousan, F.D., Drost, M., and Hansen, P.J. (2005) Factors associated with early and mid-to-late fetal loss in lactating and non-lactating Holstein cattle in a hot climate. J. Anim. Sci., 83, 1017-1022. Robbins, K. R., I. Misztal, and J. K. Bertrand. 2005. A practical longitudinal model for evaluating growth in Gelbvieh cattle. J. Anim. Sci. 83:29-33. Robbins, K. R., I. Misztal and J. K. Bertrand. 2005. Joint longitudinal modeling of age of dam and age of animal for growth traits in beef cattle. J. Anim Sci. 2005 83:2736-2742. Roth, Z., and Hansen, P.J. (2005) Disruption of nuclear maturation and rearrangement of cytoskeletal elements in bovine oocytes exposed to heat shock during maturation. Reproduction, 129, 235-244. Tsuruta, S., I. Misztal, and T. J. Lawlor. 2005. Current Day's Prediction of a Changing Trait. Productive Life of US Holsteins. J. Dairy Sci. 88:1156-1165. Meeting Abstracts and Experiment Station Reports: Carothers, RE, CS Whisnant. 2005. Effects of post-insemination CIDR on embryonic loss associated with heat stress in dairy cattle. J Anim Sci 83: Suppl. 1, p. 169. Cuadra, E.J., R.C. Vann, W.A. Bennett, R. Johnson, S.T. Willard and T. Kiser. 2005. Effects of intra-vaginal progesterone releasing devices on the survival of embryos transferred to recipient suckling multiparous beef cows. Southern Section American Society of Animal Science, Little Rock, AR, p. 12 (abstract # 43). Denson, A., M. Jones, S. Bowers, A. Dos Santos, K. Graves, K. Moulton and S. Willard. 2005. Effects of supplemental progesterone administration on pregnancy rate and resynchronization in lactating dairy cattle during mild heat stress and non-heat stress conditions. ASAS Annual Meeting, Cincinnati, OH; July, 2005. Denson, A., S. Schmidt, S. Bowers, T. Dickerson, K. Graves, R. Vann and S. Willard. 2005. Growth traits and reproductive parameters of Holstein and Gir (Bos indicus) x Holstein bulls and heifers. Southern Section American Society of Animal Science, Little Rock, AR, p. 12 (abstract # 46). Frietas, M., I. Mistral, J. Bohmanova, and J. West. 2005. Quantifying the level of heat stress in a southeastern dairy using weather recording on- and off-farm. J. Dairy Sci. 88(Suppl. 1):353. Jones, M., A. Denson, E. Williams, A. Dos Santos, K. Graves, A. Kouba and S. Willard. 2005. Assessing pregnancy status using digital infrared thermal imaging in Holstein heifers. ASAS Annual Meeting, Cincinnati, OH; July, 2005. Jones, M., A. Denson, S. Bowers, K. Moulton, E. Williams, K. Graves, A. Dos Santos, A. Kouba and S. Willard. 2005. Thermography of the vulva in Holstein dairy cows: A comparison of estrus vs. diestrus. ASAS Annual Meeting, Cincinnati, OH; July, 2005. West, J. W. 2005. Feeding and nutrition management for hot weather. Pages 97-106 in Proc. 7th Western Dairy Mgt. Conf.,Reno, NV. Whisnant, C.S. 2006. Summary of Heat Stress Related Research at Annual Meeting of North Carolina Dairy Producers, February 23, 2006, Salisbury, NC Wildman, C., J. West, and J. Bernard. 2005. A comparison of methods for determining body temperature of Holstein cows during hot weather. J. Dairy Sci. 88(Suppl. 1):43. Wildman, C. D., J. W. West, and J. K. Bernard. 2005. Relationship between dietary cation-anion difference and protein metabolism in lactating dairy cows. Univ. of GA, College of Agric. and Environ. Sci., Dept. of Anim. & Dairy Sci. 2004 Annual Report, pp. 200-208. Worley, J. W. and J. K. Bernard. 2005. Use of high volume low speed (HVLS) fans for cooling dairy cows in a free stall barn in a hot humid climate. ASAE Paper No. 054112. ASAE, St. Joseph, MI.