Browsing by Author "Cunningham, Samantha Fern"
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Item Early Life Measures of Size as Related to Weights and Productivity in Beef Cows and Carcass Traits in Steers(2013-12-10) Cunningham, Samantha FernThe overall objective of this study was to investigate various measures of cattle size. Records from three separate studies (herds) at Texas A&M University were used to evaluate relationships of birth and weaning measures (n = 750) with size and productivity of females (n = 2,800 records from 450 animals) and carcass traits (n = 450) of steers. Cattle were F1 crosses sired by Angus, Brahman, Boran, Gir, Indu-Brazil, Nellore, and Tuli. Relationships between cow traits and carcass traits of steer mates were also investigated. Animals were classified into Small, Medium and Large frame size categories based on weaning age hip heights. Considerable differences in cow weight were observed within the same frame size category, and larger differences in weight within the same frame category was observed across study herds (which also differed in breed composition) than between different frame size categories within study herds in most cases; however, the large degree of confounding between frame size category and breed type prevented conclusive findings solely based on frame size category. Cow weight appeared to plateau at parity five, and in these data, this was considered to represent mature cow weight. Ranking of steer carcass weights based on frame score category followed expectations within study herds, but similar to cow weights these also varied considerably within the same frame category across study herds. Birth weight and cannon bone length accounted for 0 to 40% of the variation in parity-five weight of females and 1 to 52% of the variation in hot carcass weight of steer mates depending upon sire breed and study herd; use of weaning (weight, height, frame score) traits accounted for 2 to 46% of the variation in parity-five weight of females and 13 to 67% of the variation in hot carcass weight of steer mates, again depending upon sire breed. Different patterns were observed between females and males depending upon sire breed. Based on results seen here weaning age designation of cattle frame size may not be a precise classification of mature size, similar frame size designations can vary considerably in weight across different genetic types, and mature size classification of beef cows alone does not guarantee productivity measures, particularly when frame size is confounded with genetic background.Item Evaluation of F1 cows sired by Brahman, Boran, and Tuli for reproductive and maternal performance and cow longevity(Texas A&M University, 2005-11-01) Cunningham, Samantha FernBirth (BW) (n = 1,107) and weaning weight (WW) (n = 1,024), pregnancy rate (PR) (n = 1,255), calf crop born (CCB) (n = 1,232), calf crop weaned (CCW) (n = 1,225), and cow??s weight at palpation (CW) (n = 1,403) were evaluated from 1994 to 2004 in 143 F1 females who were sired by Brahman (B), Boran (Bo), and Tuli (T) bulls and who were out of Angus and Hereford cows. In 2004, mouth scores (MS) (n = 71) were assigned to the remaining females. PR, CCB, CCW, CW, and BCS were evaluated using a model that consisted of sire of dam breed, dam of dam breed, and calf??s birth year/age of dam as fixed effects. Sire of dam within sire breed of dam and dam within sire of dam within sire breed of dam were used as random effects. BW and WW were analyzed using the same model including calf??s gender. Two-way interactions were tested for significance. Year/age was significant for all traits (P < 0.05). Adjusted means for BW for calves out of cows by B, Bo, and T sires were 35.66, 35.38, and 35.59 kg respectively, and were not different (P > 0.05). Adjusted means for WW for calves out of cows by B, Bo, and T sires were 233.4, 220.1, and 208.2 kg respectively, and were significantly different. For both BW and WW, male calves were heavier (P < 0.05) than females. Adjusted means for PR for females sired by B, Bo, and T bulls were 0.914, 0.945, and 0.920, and were not different (P > 0.05). Adjusted means for CCB for females sired by B, Bo, and T bulls were 0.890, 0.943, and 0.910 respectfully, and Bo was higher (P < 0.05) than B. CCW showed the same ranking as CCB with adjusted means of 0.834, 0.887, and 0.857 for cows by B, Bo, and T bulls, with Bo being higher (P < 0.05) than B. CW adjusted means, in the fall of 2002, were 594.29, 519.38, and 517.3 kg. B-sired females were heavier (P < 0.05) than Bo- or T- sired cows. More Bo- (P = 0.013) and B-sired (P = 0.003) cows had solid mouths in 2004 than T-sired cows.