Relationships among udder shape, udder capacity, cow longevity and calf weights

Udder capacity and udder shape were scored on 3- to 10-yr-old cows from a large Hereford herd. Udder capacity was scored from 1 (small) and 5 (large) and udder shape was scored from 1 (balanced, udder level with ground) to 5 (unbalanced, funnel-shaped udder). Data were analyzed within age of cow for udder capacity scores from 1 to 4 and for udder shape scores from 1 to 3 because of the limited number of observations in other categories. Year of birth of cow was a significant source of variation in both udder capacity and udder shape. Days in lactation (ranging from 81 +/- 23 d in 3-yr-old cows to 71 +/- 25 d in 4-yr-old cows) was an important source of variation for udder capacity; as lactation progressed udder capacity score declined. Body condition of the cow was an important source of variation for udder capacity in 3- and 4-yr-old cows; cows with more external body condition had larger udder capacity scores. The heritability estimates of udder capacity and udder shape for 3-yr-old cows were .12 +/- .14 and .15 +/- .16, respectively; the repeatability estimates of scores over years were .14 +/- .02 and .16 +/- .03, respectively. Residual correlations between udder capacity and udder shape were low, ranging from -.10 in 3-yr-old cows to .10 in 6-yr-old cows. Neither udder characteristic affected the number of years a cow remained in the herd, but cows with unbalanced udders had more udder defects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis on Growth and Development Pattern of Holstein Cows in Changji Area of Xinjiang

The aims of this study were to understand the relationship between the indexes of body size and body weight in Holstein cows, and the variation pattern of body size and body weight of different age stages of Holstein cows in Changji area of Xinjiang were analyzed.This study based on the measurement record of the body size and body weight of 2 972 Holstein cows of different age stages from 2012 to 2013 in Changji area of Xinjiang, obtained the body size index of different age stages, and mapped out the cumulative growth curve, absolute growth curve and relative growth curve;At the same time, carried on a correlation analyses between each body size index and body weight of Holstein cows.The results showed that along with the increase of age, body size index and body weight of Holstein cows were increasing;At the age of 1 to 3, the growth and development were rapid, it was the most important period for the growth and development of cattle.The correlation coefficients among body height, body length, chest circumference, cannon circumference and body weight were reached significant level (P< 0.01).It was important to pay special attention to breeding management of Holstein cow before three years old, and ensured its nutritional requirements in order to achieve the best physical condition in the process of breeding.     

新疆昌吉地区荷斯坦奶牛生长发育规律分析

试验旨在分析新疆昌吉地区不同年龄阶段荷斯坦奶牛体尺、体重变化规律,了解荷斯坦奶牛体尺、体重指标之间的相关性。本研究对新疆昌吉地区测定的2012~2013年2 972头次不同年龄阶段的荷斯坦奶牛体尺、体重记录进行处理得出各年龄阶段的体尺指数,分别绘制了累积生长曲线、绝对生长曲线和相对生长曲线;并对荷斯坦奶牛各体尺指标与体重进行了相关性分析。结果表明,荷斯坦奶牛体尺、体重随着年龄的增加均呈递增趋势,在1~3岁时生长发育迅速,3岁以后,其生长速度和生长强度逐渐下降;体高、体长、胸围、管围和体重间的相关系数均达到极显著水平(P< 0.01)。在实际生产中,要特别注意荷斯坦奶牛3岁以前的饲养管理,保证其营养需求以达到最佳生理状态。     

Association between cow reproduction and calf growth traits and ELISA scores for paratuberculosis in a multibreed herd of beef cattle

The objective of this research was to assess the association between 4 cow reproductive and weight traits, and 2 preweaning calf traits and ELISA scores for paratuberculosis (0 = negative, 1 = suspect, 2 = weak-positive, and 3 = positive) in a multibreed herd of cows ranging from 100% Angus (A) to 100% Brahman (B). Cow data were 624 gestation lengths (GL), 358 records of time open (TO), 605 calving intervals (CI), and 1240 weight changes from November to weaning in September (WC) from 502 purebred and crossbred cows. Calf data consisted of 956 birth weights (BWT), and 923 weaning weights adjusted to 205 d of age (WW205) from 956 purebred and crossbred calves. Traits were analyzed individually using multibreed mixed models that assumed homogeneity of variances across breed groups. Covariances among random effects were assumed to be zero. Fixed effects were year, age of cow, sex of calf, year × age of cow interaction (except WC), age of cow × sex of calf interaction (only for WC), and covariates for B fraction of sire and cow, heterosis of cow and calf, and ELISA score. Random effects were sire (except for TO and CI), dam, and residual. Regression estimates of cow and calf traits on ELISA scores indicated that lower cow fertility (longer TO), lower ability of cows to maintain weight (negative WC), lower calf BWT, and lower calf WW205 were associated with higher cow ELISA scores. Further research on the effects of subclinical paratuberculosis in beef cattle at regional and national levels seems advisable considering the large potential economic cost of this disease.     

Effects of supplemental feeding interval on adult cows in western Texas

Two experiments involving Brangus and Hereford x Brangus cows (3 to 10 yr) were conducted at four locations in western Texas to determine the effects of supplemental feeding interval on serum urea nitrogen (SUN) patterns, intake of supplement and forage, and winter changes in live body weight and condition score. Treatments were control (Control; no supplemental feed) and the equivalent of .91 kg/d of cottonseed meal (CSM) fed daily (Daily), three times per week (3T/WK), or one time per week (WK). At each location, one pasture group was given all four treatments (four cows/treatment) using Calan gates. In Exp. 1, conducted in 1994-95, blood samples were obtained for determining SUN during the last week of the study. Experiment 2, conducted in 1995-96, included both an individually fed herd and four additional herds at each location that were group-fed the four treatments. Experiment 2 included estimates of intakes of both CSM and forage in both individually fed and group-fed herds. A bolus containing chromium (Cr-bolus) was used to estimate fecal output in the individually fed cows. A double marker technique was used to determine total (Cr-bolus) and CSM (Yb) intakes in the group-fed cows. Data included initial and final cow weights and condition scores (Exp. 1 and 2), SUN patterns (Exp. 1), and supplement, forage, and total intakes (Exp. 2). Feeding CSM to range cows increased SUN concentrations (Exp. 1), reduced losses in live body weight and body condition score (Exp. 1 and 2), and tended to decrease forage intake by the approximate amount of the supplement (Exp. 2). Generally, providing supplement as infrequently as once per week reduced losses in live body weight and body condition score compared with control and was as effective as once daily supplementation. For the group-fed cows, supplement intake, forage intake, and live body weight change were more variable within groups with once daily feeding than when supplement was fed less frequently. These data indicate that feeding as infrequently as one time per week can be effective nutrition management for adult cows grazing native range.     

Breed comparisons of Angus,Charolais, Hereford,Jersey, Limousin,Simmental, and South Devon for weight,weight adjusted for body condition score,height, and body condition score of cows

Breed means and differences for weight (CW, n = 19,851), height (CH, n = 14,553), and condition scores (CS, n = 19,536) recorded in four seasons per year were evaluated for 881 cows ranging from 2 to 7 yr of age from Cycle I of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Cows were straightbred Herefords and Angus and topcrosses from mating of Hereford, Angus, South Devon, Jersey, Simmental, Limousin, and Charolais sires to Hereford and Angus dams. The model included cow age, season of measurement, and their interactions, with year of birth, pregnancy-lactation (PL) code, and breed group as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as covariate. Model for CH excluded PL. Random effects were additive genetic and permanent environmental effects. Data were analyzed by REML. Differences due to breeds of sire were significant for all traits. Differences were generally maintained across ages, with few interchanges in ranking through maturity. Rankings were in the following order: Jersey (lightest and shortest), Hereford-Angus (and reciprocal), Limousin, South Devon, Simmental, and Charolais (heaviest and tallest). The only exception was that Limousin-sired cows were heavier than South Devon-sired cows after 5 yr of age. Cows sired by breeds of British origin tended to be lighter than breeds of continental European origin. Adjustment for condition score changed estimates of breed differences. Rankings of breed groups, however, were generally the same for actual weight and weight adjusted for condition score. Results indicated that the part of the differences in weight due to differences in condition were of small magnitude. Differences tended to increase when adjusted for condition score, especially in contrasts of continental vs British breeds. Differences among breed groups for height followed differences for weight closely.     

Breed comparisons of Angus,Brahman, Hereford,Pinzgauer, Sahiwal,and Tarentaise for weight,weight adjusted for condition score,height, and body condition score

Data from topcross cows (n = 468) from six breeds of sire (Angus, Brahman, Hereford, Pinzgauer, Sahiwal, Tarentaise) and two breeds of dam (Angus and Hereford) of Cycle III of the Germplasm Evaluation (GPE) program at the U.S. Meat Animal Research Center (MARC) comprising cow weight (CW, n = 9,012), height (CH, n = 9,010), and condition score (CS, n = 8,991) recorded in four seasons per year from 2 to 6 yr of age were used to estimate breed-group differences. The mixed models included cow age, season of measurement and their interactions, year of birth, pregnancy-lactation code (PL), and breed group as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as a linear covariate. Model for CH excluded PL. Random effects were additive genetic and permanent environmental effects. Differences among breed-groups were significant for all traits for different ages and were maintained across ages, with few interchanges in ranking through maturity. Cows with Sahiwal sires were lightest (392 to 479 kg), whereas Hereford-Angus (HA) reciprocal-cross cows were shortest (119 to 123 cm) at each age. Cows with Brahman sires were heaviest and tallest among breed groups at all ages, exceeding HA cows by 19 to 24 kg and 9 to 10 cm, respectively. Cows with Pinzgauer and Tarentaise sires were intermediate for weight and height and interchanged ranking across ages. Differences in weight due to differences in condition seemed to be of small magnitude because adjustment for condition score did not affect rankings of breed groups across ages. Important changes for mature size of cows can be achieved by breed substitution with the breeds of sires used in this study.     

Effects of Thigh and Rear Udder Hygiene on Daily Milk Yield and Somatic Cell Score

To investigate the importance of dairy cow hygiene for management, the objective of this research was to determine the relationship between hygiene scores and daily milk yield as well as somatic cell score(SCS), and also the relationship between thigh and rear udder hygiene scores.The hygiene scores of thigh and rear udder were collected from 472 lactating cows in 3 Holstein dairy farms in Henan province, and dairy herd improvement(DHI) data for July, 2014 was also collected.After correcting the influence of fixed effects including lactating stage and dairy-parity, the effects of thigh and rear udder hygiene scores on daily milk yield and SCS were analyzed using SAS 9.1 with general linear model(GLM) procedure.The results showed that thigh and rear udder hygiene scores had no significant effect on average daily milk yield and SCS(P>0.05).For average daily milk yield, the regression coefficients of thigh and rear udder hygiene scores were-0.14 and-0.02, respectively.This meaned if thigh and rear udder hygiene scores increased 1 score, average daily milk yield of each cow would decrease 0.14 and 0.02 kg, respectively.For SCS, when thigh hygiene score ≥ 4, the proportion of cows with SCS ≥ 5 increased extremely significantly(P<0.01);when rear udder hygiene score ≥ 3, the proportion of cow with SCS ≥ 5 tended to increase(P=0.0546).Significant test for correlation and correlation coefficient estimation results showed that, there was a extremely significantly positive correlation discovered between thigh and rear udder hygiene scores(P<0.01).Therefore, hygiene scores was not only a management indicator, also could help understand udder health condition, which was beneficial for management.     

Loser cows in Danish dairy herds: definition, prevalence and consequences

During the last few years, many Danish dairy farmers have expressed increasing concerns regarding a group of cows, which we have chosen to term ‘loser cows’. Until now, a loser cow has not been described scientifically. We defined a loser cow on the basis of a clinical examination of the cow. A total of 15,151 clinical examinations were made on 6,451 individual cows from 39 randomly selected, large Danish dairy herds with loose-housing systems using a clinical protocol. Scores for the clinical signs lameness, body condition, hock lesions, other cutaneous lesions, vaginal discharge, condition of hair coat and general condition were converted into a loser cow score. Cows with a loser cow score of 8 or more were classified as loser cows. The overall prevalence of loser cows was 2.15%, 4.50% and 2.98% during the first, second and third round of herd visits, respectively.

The associations between the loser cow state and milk production, mortality, morbidity, culling and workload for the farmer were evaluated using data from herd visits and from the Danish Cattle Database and a number of different statistical techniques. It was concluded that the loser cow state has significant negative consequences for both the farmer and the cow. On average, loser cows yielded 0.61 to 2.24 kg energy corrected milk less per day than non-loser cows depending on parity. Hazard ratio for death or euthanasia was 5.69 for loser cows compared to non-loser cows. Incidence rate ratio for disease treatments was 0.69 for non-loser cows compared to loser cows. Loser cows were often culled in an ‘unfavourable’ way and generally caused extra workload for the farmer.

A simplified version of the loser cow score was evaluated and is recommended for future research and use in practice.     

奶牛股部和乳房后部清洁度对日产奶量及体细胞数的影响

为探究奶牛体表清洁度在实际生产中的应用意义,本研究通过评价河南省3个奶牛场472头泌乳天数在0~330 d的中国荷斯坦奶牛股部清洁度和乳房后部清洁度,并结合2014年7月河南省牛奶记录系统(dairyherd improvement,DHI)中心提供的数据,对清洁度与平均日产奶量、体细胞数评分(somatic cell score,SCS)的关系进行分析,并探究两个清洁度评分之间的相关关系。采用广义线性模型(GLM)对数据进行统计分析,固定效应模型除清洁度评分外,还包括泌乳阶段效应和场-胎次效应等。结果表明,清洁度评分对SCS和平均日产奶量均无显著影响(P>0.05)。股部清洁度评分对平均日产奶量回归系数为-0.14,即每增加1分,奶牛平均日产奶量降低0.14 kg/头;乳房后部清洁度评分对平均日奶量回归系数为-0.02,每增加1分,奶牛平均日产奶量降低0.02 kg/头。对于SCS,股部清洁度评分≥ 4分时,SCS ≥ 5的比例极显著增加(P<0.01);乳房后部清洁度评分≥ 3分时,SCS ≥ 5的比例有增加趋势(P=0.0546)。相关性检验和相关系数估计结果显示,股部和乳房后部清洁度评分间呈极显著正相关(P<0.01)。因此,奶牛体表清洁度不仅是牛群的管理指标,而且可通过清洁度评分有效了解牛群乳房的健康状况,对日常生产过程具有很大帮助。     

Variation in somatic cell counts of milk samples from individual cows

Somatic cell counts of 2570 milk samples from 765 cows collected bimonthly from November 1975 to May 1976 were transformed to logarithmic values and analysed statistically. Components of variance were estimated as follows: Herds 0.033 (13 %), age groups 0.021 (8%), cows (within herds and age groups) 0.080 (31%), months 0.014 (6%), residual 0.107 (42%). Correction of actual cell counts for the influence of milk yield on the day of sampling led to only small changes in the magnitude of the various components. The coefficient of correlation between samples from the same cow was computed as 0.60 when the samples were from the same lactation, and 0.37 for samples from consecutive lactations.The proportionately small variation among herds as compared to the variation among cows of the same herd throws doubt on the efficiency of cell counting in samples of herd milk as a way of identifying cows with high cell counts.     

Comparisons of Angus-, Braunvieh-, Chianina-, Hereford-, Gelbvieh-, Maine Anjou-, and Red Poll-sired cows for weight,weight adjusted for body condition score,height, and body condition score

Data from Angus, Hereford, and top-cross cows (n = 641) from 2- to 8-yr-old daughters of seven breeds of sires included in Cycle II of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center, comprising cow weight (CW, n = 15,698), height (CH, n = 15,676), and condition score (CS, n = 15,667), were used to estimate breed-group differences. Data were recorded in four seasons of each year (1975 to 1982). The mixed model included cow age, season of measurement, and their interactions, year of birth, pregnancy-lactation code (PL), and breed-group as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as covariate. The model for CH excluded PL. Random effects were additive genetic and permanent environmental effects. Differences among breed-groups were significant for all traits at different ages and were maintained across ages, with few interchanges in ranking through maturity. Cows were ranked (by breed of sire) in the following order for weight: Red Poll (lightest), Hereford-Angus (reciprocal), Braunvieh, Gelbvieh, Maine Anjou, and Chianina (heaviest). In general, cows sired by breeds of British origin were lighter and shorter than those of continental origin. Differences in weight due to differences in condition seemed to be of small magnitude because making an adjustment for condition score did not affect rankings of breed groups across ages. Differences among breed groups for height were consistent with differences for weight. Cows from Chianina sires were taller than Hereford-Angus cows by 14 to 15 cm across ages. In this study, breed of sire effects were significantly different for the mature size of their daughters.     

Effects of supplementation with high linoleic or oleic cracked safflower seeds on postpartum reproduction and calf performance of primiparous beef heifers

Primiparous Angus x Gelbvieh (n = 36) rotationally crossed beef cows (initial BW = 487.9 +/- 10.5 kg, body condition score = 5.5 +/- 0.02) were utilized to determine effects of supplemental safflower seeds high in linoleic (76% 18:2) or oleic (72% 18:1) acid on cow BW change, body condition score, milk production and composition, calf weight gain, cow serum metabolites, and metabolic hormones. On d 3 postpartum, cows were randomly assigned to one of three isonitrogenous dietary supplements with equal total quantity of TDN: corn-soybean control supplement (n = 12); high-linoleate safflower seeds (n = 12); or high-oleate safflower seeds (n = 12). Safflower-seed supplements were formulated to provide 5% DMI as fat. Supplements were individually fed from d 3 postpartum through 90 d postpartum. Cows had ad libitum access to native grass hay (7.8% CP), trace-mineralized salt, and water. Date of parturition was evenly distributed across treatments with all cows calving within 14 +/- 0.8 d. There were no differences (P = 0.65) in total OM intake among treatments. Although cow BW change did not differ (P = 0.33) by treatment, supplementation influenced cow body condition score (P = 0.02) with linoleate-supple-mented cows in higher (P = 0.005) condition overall than oleate-supplemented cows (5.1 +/- 0.06 vs 4.9 +/- 0.06). Twenty-four-hour milk production did not differ (P = 0.68) among treatments. Percentage milk fat was not different at d 30; however, at d 60 and d 90 percentage milk fat was greater (P ( 0.05) in control and oleate-supplemented cows than in linoleate-supplemented cows. Calf BW gains (P = 0.27) and adjusted 205-d weights (P = 0.48) were not affected by supplement treatment. Supplementation did not influence serum concentrations of glucose (P = 0.38), NEFA (P = 0.61), GH (P = 0.29), IGF-I (P = 0.81), insulin (P = 0.26), or IGF-I binding proteins (P > or = 0.11). Days to conception did not differ (P = 0.40) among treatments. Although overall productivity of the primiparous cows and their calves was not altered by safflower-seed supplementation, differential effects were noted between supplements. Oleate supplementation increased percentage milk fat at d 60, and cow body condition score was lower than in linoleate-supplemented cows. Linoleate-supplemented cows had greater body condition scores by 90 d postpartum than either corn-soybean- or oleatesupplemented cows.     

Neospora caninum seroprevalence and associated risk factors in beef cattle in the northwestern United States

A Neospora caninum seroprevalence and risk factor survey of 2585 cows was conducted in 55 beef cow-calf herds located in five northwestern states of the USA. Blood samples were collected by private veterinary practitioners and management practices were surveyed using a mail questionnaire. Producers were randomly selected from those that employed these veterinarians to perform annual herd pregnancy examinations. Questions were asked about animal management, grazing and feeding, immunization and record keeping practices. Blood was collected from a systematically selected sample of cows in each herd, and age, origin, and pregnancy status were recorded. Blood samples were analyzed for antibodies against N. caninum antigen using a monoclonal antibody-based competitive inhibition (CI) ELISA. Overall seroprevalence was 24% and within herd seroprevalence ranged from 3 to 67% with a median of 19%. Within herd seroprevalence and mean inhibition percentage were different between the five states. Herds that managed their cows on range for summer grazing had lower seroprevalence than those that did not, while increased seroprevalence was associated with higher winter stocking density. Cows less than 3 years of age had higher CI ELISA inhibition percent values than cows greater than 6 years of age. No relationship was noted between serologic status and individual cow origin (purchased or raised), or pregnancy status at the time of sampling.     

Cool-season annual pastures with clovers to supplement wintering beef cows nursing calves

ABSTRACT: In December of 3 years, 87 beef cows with nursing calves (594 +/- 9.8 kg; calving season, September to November) at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures (0.45 ha/cow) that had been interseeded into a dormant common bermudagrass (Cynodon dactylon [L.] Pers.)/bahiagrass (Paspalum notatum Flugge) sod. Pastures contained 1 of the following 3 seeding mixtures (2 pastures/mixture): 1) wheat (Triticum aestivum L.) and ryegrass (Lolium multiflorum Lam., WRG), 2) wheat and ryegrass plus red clover (Trifolium pretense L., WRR), or 3) wheat and ryegrass plus white (Trifolium repens L.) and crimson clovers (Trifolium incarnatum L., WRW). All groups had ad libitum access to grass hay (12% crude protein; 58% total digestible nutrients). The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ (P > 0.27) among cows between February and June. Calf birth weights or average daily gain did not differ (P [greater than or equal to] 0.17) among treatments; however, calves grazing pastures with clovers did tend (P = 0.06) to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater (P = 0.02) for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.     

Relationship between terrain use and performance of beef cows grazing foothill rangeland

A study was conducted on foothills rangeland to determine whether grazing patterns differed among cow breeds and to determine whether there was a relationship between individual grazing patterns and performance of beef cows. Hereford (HH), Tarentaise (TT), 3/4 Hereford x 1/4 Tarentaise (3H1T), 1/2 Hereford x 1/2 Tarentaise (HT), and 1/4 Hereford x 3/4 Tarentaise (1H3T) cows were observed during the summers of 1997 (n = 183) and 1998 (n = 159). Locations of individual cows were recorded two to three times per week during 1.5- to 2.5-h periods in the morning by observers on horseback. Statistical models included cow breed, age, and nursing status. Data from each year were analyzed separately. During 1997 and 1998, nonlactating cows were located at greater (P < 0.05) vertical distances from water than lactating cows. In 1998, nonlactating cows used steeper (P < 0.05) slopes than lactating cows. However, nonlactating cows did not travel as far horizontally from water (P < 0.05) as lactating cows in 1997. Younger cows (3 yr) traveled further (P < 0.05) from water both vertically and horizontally than older cows (5+ yr) in 1997, but not during 1998. Tarentaise and 1H3T cows were observed at greater (P < 0.05) vertical distances from water than HH cows during both years of the study. During 1998, TT and 1H3T cows used steeper (P < 0.05) slopes than HH cows. Using residual correlations, there were no consistent relationships between topographic aspects of individual grazing locations and cow weight, height, and body condition score. In 1997, cows with earlier calving dates and correspondingly heavier calf weaning weights used areas that had greater vertical distances to water; however, in 1998 there were no relationships (P > 0.05) of calving date and weaning weight with cow location. During both years, pregnant and nonpregnant cows used terrain similarly (P > 0.05), which suggests that cow reproductive performance was not related to terrain use. Grazing patterns in foothills rangeland varied among cow breeds. Performance of cows that used more rugged topography was similar to cows using gentler terrain.     

Repeated-measure animal models to estimate genetic components of mature weight,hip height,and body condition score

Information on mature weight, hip height, and body condition score from Angus cows was analyzed to estimate variance components and compare prediction models. Observations from repeated measures were analyzed with animal models with or without condition score as a covariate and with or without an effect for permanent environment. Heritability (repeatability) estimates for mature weight, hip height, and condition score from Method R procedures were 0.40 (0.77), 0.62 (0.81), and 0.11 (0.38), respectively, from animal models containing a permanent environmental effect but without a covariate for condition score. Heritability estimates from animal models without a permanent environmental effect were similar to repeatability estimates from animal models with it, suggesting inflated estimates of genetic variance from models not containing a permanent environmental effect. Regressing mature weight on condition score reduced both additive genetic variance and permanent environmental variance, increasing the heritability estimate of mature weight to 0.54 and altering the biological interpretation of the trait. The covariate for condition score had little effect on hip height. Regressions of mature weight and hip height on condition score were 25.9 kg/unit of body condition score and 0.4 cm/unit, respectively. Least-squares means for mature weight and hip height tended to increase until 7 and 5 yr of age, respectively. Condition score tended to increase until 6 yr of age and decrease after 8 yr of age. Correlations between breeding value solutions for the same trait were high whether or not prediction models included a permanent environmental effect or a covariate for condition score, and whether or not the variance components used were derived from models containing a covariate for condition score. Results suggest the importance of including a permanent environmental effect in genetic prediction models for these traits. Whether mature weight should be adjusted for body condition is arguable, depending on availability of condition score predictions and tools for analyzing mature weight and condition score predictions in an environment-specific context.     

Genetic relationships between sex-specific traits in beef cattle: mature weight, weight adjusted for body condition score, height and body condition score of cows, and carcass traits of their steer relatives

Data from the first four cycles of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center (USMARC) were used to investigate genetic relationships between mature weight (MW, n = 37,710), mature weight adjusted for body condition score (AMW, n = 37,676), mature height (HT, n = 37,123), and BCS (n = 37,676) from 4- to 8-yr old cows (n = 1,800) and carcass traits (n = 4,027) measured on their crossbred paternal half-sib steers. Covariance components among traits were estimated using REML. Carcass traits were adjusted for age at slaughter. Estimates of heritability for hot carcass weight (HCWT); percentage of retail product; percentage of fat; percentage of bone; longissimus muscle area; fat thickness adjusted visually; estimated kidney, pelvic, and heart fat percentage; marbling score; Warner-Bratzler shear force; and taste panel tenderness measured on steers were moderate to high (0.26 to 0.65), suggesting that selection for carcass and meat traits could be effective. Estimates of heritability for taste panel flavor and taste panel juiciness were low and negligible (0.05 and 0.01, respectively). Estimates of heritability from cow data over all ages and seasons were high for MW, AMW, and HT (0.52, 0.57, 0.71; respectively) and relatively low for BCS (0.16). Pairwise analyses for each female mature trait with each carcass trait were done with bivariate animal models. Estimates of genetic correlations between cow mature size and carcass composition or meat quality traits, with the exception of HCWT, were relatively low. Selection for cow mature size (weight and/or height) could be effective and would not be expected to result in much, if any, correlated changes in carcass and meat composition traits. However, genetic correlations of cow traits, with the possible exception of BCS, with HCWT may be too large to ignore. Selection for steers with greater HCWT would lead to larger cows.     

Comparisons of Angus, Charolais, Galloway, Hereford, Longhorn, Nellore, Piedmontese, Salers, and Shorthorn breeds for weight, weight adjusted for condition score, height, and condition score of cows

Breed differences for weight (CW), height (CH), and condition score (CS) were estimated from records (n = 12,188) of 2- to 6-yr-old cows (n = 744) from Cycle IV of the U.S. Meat Animal Research Center's Germplasm Evaluation (GPE) Program. Cows were produced from mating Angus and Hereford dams to Angus, Hereford, Charolais, Shorthorn, Galloway, Longhorn, Nellore, Piedmontese, and Salers sires. Samples of Angus and Hereford sires were 1) reference sires born from 1962 through 1970 and 2) 1980s sires born in 1980 through 1987. The mixed model included cow age, season of measurement and their interactions, year of birth, pregnancy-lactation code (PL), and breedgroup as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as a linear covariate. The model for CH excluded PL. Random effects were additive genetic and permanent environmental effects associated with the cow. Differences among breed groups were significant (P < 0.05) for all traits and were maintained through maturity with few interchanges in ranking. The order of F1 cows for weight was as follows: Charolais (506 to 635 kg for different ages), Shorthorn and Salers, reciprocal Hereford-Angus (HA) with 1980s sires, Nellore, HA with reference sires, Galloway, Piedmontese, and Longhorn (412 to 525 kg for different ages). Order for height was as follows: Nellore (136 to 140 cm), Charolais, Shorthorn, Salers, HA with 1980s sires, Piedmontese, Longhorn, Galloway and HA with reference sires (126 to 128 cm). Hereford and Angus cows with reference sires were generally lighter than those with 1980s sires. In general, breed differences for height followed those for weight except that F1 Nellore cows were tallest, which may in part be due to Bos taurus-Bos indicus heterosis for size.