Brief Summary of Minutes of Annual Meeting

Annual Report S-1086

Years 2021 – 2022

 Project Title: S-1086: Enhancing sustainability of beef cattle production in Southern and Central US through genetic improvement

 Agencies and Principal Investigators:

University of Arkansas:  J. G. Powell, B. R. Kutz, B. P. Littlejohn

University of Florida:  R. Mateescu

University of Georgia:  R. Rekaya

Kansas State University: M. Rolf

Mississippi State University:  T. Smith, R. C. Vann, B. Rude

Texas A&M University:  J. O. Sanders, D. G. Riley, A. D. Herring

 III.    Objectives:

 1. Estimate genetic variation associated with animal health and structural soundness using classical animal breeding and genomic techniques to facilitate sustainable beef cattle production systems.

 2. Systems approach to analyzing novel ERTs associated with female production including longevity, fertility, and meat quality database creation.

 3. Documentation of genetic components and development of thermotolerance measurements pertaining to heat tolerance adaptive traits in sustainable beef cattle production systems.

 Procedures:

        Objective 1.1 Eye and facial pigmentation

 We will use photographs and digital quantification software to determine proportion of eyelid with pigmentation. Each animal will have one photo to identify the animal (primarily have used tag or brand), one of full face straight on to clarify markings, one of eye straight across on left side, one of eye aiming up (to characterize the eyelid under the upper eyelashes) on the left side, one of eye straight across on right side, and one of eye aiming up on the right side. Quantifications of pigmentation will be conducted using procedures developed by Davis et al. (2015).  Multiple locations will contribute to this objective. Evaluated breed types will include 1) Hereford, 2) Hereford-Bos taurus crosses, and 3) Hereford-Bos indicus crosses (including Braford in this category even though it is recognized as a distinct breed). The target number of animals in each breed type category is 2,000.

 Objective 1.2 Udder conformation

 Cattle will be evaluated for udder conformation traits and scored according to BIF guidelines (2010) for Udder Suspension and Teat size. Scores for each trait range from 1 to 9 with 9 indicating tight suspension and small teat size and will be evaluated at weaning. In addition, any udder abnormalities such as evidence of mastitis, dead quarters, tumors, injuries or other diseases will be recorded. Cow traits related to weaning performance and calf traits to include birth weight and date, weaning weight and date and post weaning performance will be evaluated.

 Objective 1.3 Foot Structure

 Cattle will be evaluated for hoof conformation traits and scored according to American Angus Association (2015) for Claw Set and Toe Angle. Scores for each trait range from 1 to 9 with 1 indicating straight pasterns and short toes, and 9 indicating curled toes and crossed claws. Hooves will be evaluated at weaning. Additionally, trim records will be recorded. Cow traits related to reproductive performance and calf traits to include birth weight and date, weaning weight and date and post weaning performance will be evaluated.

Objective 3.2 Hair Shedding

 Documentation of genetic components pertaining to heat tolerance adaptive traits in sustainable beef cattle production systems.Cattle will be evaluated for hair shedding scores from March through July (28 day intervals, 5 scores). Shedding scores will on a 1 through 5 scale:  where 1 = slick short summer coat (100% shed); 2 = hair coat is mostly shed (75% shed); 3 = hair coat is halfway shed (50% shed); 4 = hair coat exhibits initial shedding (25% shed); and 5 = full winter coat (0% shed).  In addition, cow traits related to reproductive performance, growth performance, and culling will be recorded. Calf traits to be recorded include birth weight and date, weaning weight and date.

 Progress of Work:

 Objective 1.1

Arkansas: An Angus-based fall calving cowherd (n ≈ 167) was observed and photos of eye pigmentation were collected from white-faced cows and calves at weaning in white-faced cows housed at the University of Arkansas beef research unit near Fayetteville..  Whole blood samples were also collected and frozen from calves. Cow traits related to weaning performance and calf traits to include birth weight and date, weaning weight and date were recorded for possible future evaluation.  Photos and whole blood will be transferred to Dr. Riley at TAMU in order to collaborate with other locations that are involved with collecting similar data.         

Mississippi- Photographs of each eye were taken on purebred Hereford and Hereford-cross calves to assess eye pigmentation. Pictures will be sent for quantification and contribution to this objective.  Pictures were taken of both eyes for 26 head of purebred Hereford females and 1 Hereford X Angus female. 

Texas- DNA collected on approximately 200 animals in this year (over 4,000 animals with records and DNA).  More photographs (approximately 200 animals) added to the database

 Objective 1.2

 Arkansas: An Angus-based fall calving cowherd (n ≈ 171) was observed and udder scores were recorded at calving in the Fall of 2021 and at weaning in May 2022.  Cows were evaluated on a scale from 1 to 9 for udder suspension and teat size according to BIF guidelines. A score of 1 indicated a very pendulous suspension and large, balloon shaped teats and a score of 9 represented a tight suspension and refined teat size. Phenotypic data for cow age, Pre-Breeding BW, Pre-Breeding BCS , BCS of cow at weaning, BW of cow at weaning, AI pregnancy and overall pregnancy, along with calf weaning weight, and adjusted 205-day weaning weight (adjusted for dam age and calf gender) were collected. Means will be generated for suspension and teat scores by dam age. Cows receiving a suspension or teat score of 5-9 or a combination of the two will be considered to have an overall “acceptable” udder. Those that do not will be considered “unacceptable”.  Cow performance data will be analyzed using the acceptability parameters described with CORR, GLIMMIX, MIXED, and FREQ procedures of SAS.  Significance was declared at P ≤ 0.05 and tendencies were observed at 0.05 < P ≤ 0.10.

Frequency of cows in the acceptable range far outweighed the unacceptable cows at both evaluating periods 133 to 16 at calving and 162 to 4 at weaning. Udder Conformation on weaned calf performance was not significantly different (P > 0.24). Calf weaning weight was not affected by udder conformation (P > 0.46) There did exist a low negative correlation between cow age and conformation at calving and weaning (r= -0.234, -0.151 respectively). Cows with unacceptable udders had higher pre-breeding body weights (P = 0.32) and pre-breeding body condition scores (P = 0.41) compared to cows with acceptable udders. There was no correlation between udder confirmation and pre-breeding body condition scores. Udder confirmation did not affect weaning body weight (P = 0.812), weaning body condition scores (P = 0.588), overall AI conception rates (P = 0.753), or overall pregnancy rates (P = 0.601). 

Mississippi- Data were collected on fall calving purebred Angus, Hereford cows and spring calving commercial cows. Udder and teat scores were recorded within 24 hours after calving, during mid-lactation and at weaning. Data will be combined with other stations at the end of the project for analysis.  Udder and teat scores were taken on 28 Angus and 27 purebred Hereford cows at birth, mid-lactation, and weaning.

Texas- 

Brahman udder scores mid-lactation

Correlations of weaning weight with udder suspension 0.09, and teat size –0.05.

 Brahman udder scores weaningension

 Correlations of weaning weight with udder suspension –0.246, and teat size 0.269. 

 Objective 1.3

Arkansas:  An Angus-based fall calving cowherd (n ≈ 171) was observed and foot scores were recorded at weaning in May 2022.  Cows were evaluated on a scale from 1 to 9 for foot angle and claw set according to the American Angus Association with 1 indicating straight pasterns and short toes, and 9 indicating curled toes and crossed claws. Phenotypic data for cow age, Pre-Breeding BW, Pre-Breeding BCS, BCS of cow at weaning, BW of cow at weaning, AI pregnancy and overall pregnancy, along with calf weaning weight, and adjusted 205-day weaning weight (adjusted for dam age and calf gender) were collected. Means will be generated for suspension and teat scores by dam age. We assigned cows with a claw or angle score between 4 and 6 to have an overall “acceptable” foot score. Those that are not “acceptable” will be deemed “unacceptable”. Cow performance data will be analyzed using the acceptability parameters described with CORR, GLIMMIX, MIXED, and FREQ procedures of SAS.  Significance was declared at P ≤ 0.05 and tendencies were observed at 0.05 < P ≤ 0.10.

 Mean Cow Age of Acceptable foot structure was 6.95 and unacceptable was 5.36.  Frequency of Acceptable cows was 43 and unacceptable was 85. Acceptable foot structure had a significant impact on Pre-breeding BW (P < 0.001), Pre-Breeding BCS (P < 0.05), Weaning BW (P < 0.05), Weaning BCS (P < 0.05).  Calf weaning weight was not affected by foot structure (P > 0.1). However, acceptable foot structure tended to impact overall AI pregnancy rates (P = 0.074). Positive correlation did exist between foot soundness and cow age (r=0.343), Pre-Breeding BW (r=0.312), Pre-Breeding BCS (r=.184), Weaning BW (r=0.261) and Weaning BCS (r=0.184).  Calf weaning weight tended to be significantly correlated with acceptable foot soundness (r=0.158).  

 Objective 2

 Mississippi- Cow performance and fertility data were collected on 56 Angus and 28 Hereford purebreds and 87 commercial (Simbrah X Angus, Hereford X Angus) females.   

 Texas- Cow performance and fertility data were collected on approximately 1200 cows, most with some Brahman background.  F₂ Nellore-Angus cow fertility did not appear to differ by how the cross was made, i.e., F₁ Nellore-sired bulls bred to F₁ Nellore-sired cows; F₁ Nellore-sired bulls bred to F₁ Angus-sired cows, etc.

Objective 3        

Arkansas:  An Angus-based commercial beef cattle herd (n ≈ 167) was observed in 2021. Once monthly from March until July, at approximately 28-day intervals, mature cows and replacement heifers were evaluated for shedding on a scale from 1 to 5. A score of 5 indicates a full winter coat and a score of 1 represents a slick, short summer coat. Month of first shedding was defined as the month in which a cow received a hair coat score of 3 (approximately 50% shed) or less was reached. Hair coat scores were taken from April through July. Those that had not received a hair coat score of 3 by July were labeled “after”. Phenotypic data for cow age, pregnancy success, pre-breeding cow weight and body condition score, calf birth weight, weaning weight and adjusted weaning weight, and cow weaning weight and body condition score were collected and analyzed using the PROC FREQ and PROC GLIMMIX procedures of SAS. Significance was declared at P ≤ 0.05 and tendencies were observed at 0.05 < P ≤ 0.10.

 Frequency of MFS occurred with the following order: June> May>July. Cow age was different (P < 0.01) with MFS group means for May = 5.0, June = 6.1 and July = 5.6 with May having the lowest age and June having the greatest age and July the intermediate age. Artificial and Natural Service breeding success was unaffected by hair coat shedding (P > 0.68). Cow pre-breeding body weight and body weight at weaning was not significantly different (P > 0.19).  Calf weaning weight was not significantly different; however, calf birth weight differed (P < 0.01) with mean birth weight averaging 76, 71 and 65 pounds for calves born to cows that shed in May, intermediate for calves born to calves that shed in June, and least for calves weaned to cows that shed in July (P < 0.05). Cow weaning body condition score and prebreeding body condition score differed by MFS (P < 0.05) with cows exhibiting MFS in June showing the highest BCS at prebreeding and weaning with cows exhibiting MFS in May or June showing lower BCS at prebreeding and weaning.

Mississippi - Hair shedding scores were collected on 56 Angus and 28 Hereford purebreds and 87 commercial (Simbrah X Angus, Hereford X Angus) females. This year, a metabolism trial will be conducted with bulls from either early or late shedding dams.  All bulls will receive the same diet and nutrient digestibility will be determined for each of these two groups.  Data will be in next year’s report.  The objective of this study was to evaluate winter hair coat shedding ability and its association with uterine artery hemodynamics. Fall calving, artificially inseminated purebred Angus females (n = 29) were observed once monthly by two trained technicians for winter hair coat shedding and given a visual hair shedding score of 1 to 5 with 1 indicating 100% shed, 2 = 75% , 3 = 50% , 4 = 25% , and 5 indicating 0% shedding of winter hair coat. Month of first shedding (MFS) was determined once a female reached an average hair shedding score of ≤ 3.5 from March until July of 2019 and 2020. Uterine artery blood flow (ABF) was determined using color Doppler ultrasonography at d 150, 180, 210, and 240 of gestation. Total uterine artery (summation of ipsilateral and contralateral arteries) and ipsilateral uterine ABF, diameter, resistance and pulsatility index (PI) were analyzed using repeated measures of the MIXED procedure of SAS with significance declared at P ≤ 0.05. Fixed effects included MFS, day, year, and the respected interactions with covariates of dam body weight, ambient temperature and order of cow ultrasonography examination considered as a random effect.

Texas- Recorded monthly winter shedding scores on approximately 70 Angus cows.  Recorded approximately quarterly coat length scores on approximately 400 Bos indicus-influenced cows.

Summary:

Objective 1.1          

 Numbers of images and corresponding DNA samples are reaching appropriate levels for genome-wide association analyses.  Some interim work with image management will be required.

 Objective 1.2 

 Locations have accumulated scores across lactations and across years for approximately 300 cows. 

Objective 1.3 

Data was analyzed to determine if cow herd performance is affected by hoof score. Acceptable foot structure had a significant impact on pre-breeding cow BW, pre-Breeding cow BCS, cow BW at weaning, and cow BCS at weaning.  Calf weaning weight was not affected by foot structure; however, acceptable foot structure tended to impact overall AI pregnancy rates in these data.

Objective 2     

Accumulation of records is substantial. Combination for analyses is the next step. 

 Objective 3 

Arkansas:  Data was analyzed to determine if cow herd performance is affected by month of first shedding.  In these data, MFS score varied by cow age and influenced calf birth weight and cow prebreeding and weaning BCS.

 Mississippi:  No significant MFS by day of gestation interaction (P > 0.32) was observed for total or ipsilateral blood flow (P > 0.23). A MFS by day of gestation (P < 0.04) interaction was observed for both ipsilateral artery diameter and PI, in which females that shed by May had smaller artery diameter (0.74 vs. 0.85 cm) at day 180 of gestation and greater PI (P < 0.02; 1.48 vs. 1.03) at day 150 of gestation compared to June.