Teat scores in first-parity Gelbvieh cows: relationship with suspensory score and calf growth traits.
Teat and udder suspensory scores from 9,418 first-parity Gelbvieh cows and growth records from 19,119 calves were used to estimate genetic and environmental parameters for teat and suspensory score and to investigate the relationship of teat and suspensory score with calf growth traits and maternal genetic growth effects. First-parity cows did not have multiple records within 280 d, gave birth to one calf, were 4 yr of age or younger at first-calving, and were at least 50% Gelbvieh. Producers scored cows within 24 h of parturition. Teat score (T), a subjective measure of teat size, ranged from 0 (very large) to 50 (very small), and suspensory score (S), a subjective score of udder support, ranged from 0 (very pendulous) to 50 (very tight). Unadjusted birth weight (BW), weaning weight, and yearling weight of the calves, born in the first three parities to cows with first-parity T and S records, were used to calculate pre- and postweaning ADG (WG and YG, respectively). A mixed model was used for the multiple trait analysis of T, S, BW, WG, and YG, which included herd-year, month of calving, age of cow at calving, and sex of calf (included only for BW, WG, and YG) as systematic effects; regression on the percentage of Gelbvieh; and additive animal and maternal genetic of dam (included only for BW and WG), maternal permanent environment (included only for BW and WG), and residual as random effects. The genetic correlation between T and S was 0.95, suggesting that T and S are basically the same trait in this dataset. The genetic correlations between T (S) with direct BW, WG, and YG and with maternal BW and WG were -0.18 (-0.06), 0.38 (0.31), 0.09 (-0.01), -0.16 (-0.16), and -0.47 (-0.55), respectively, suggesting that cows with smaller teats and tighter udders produced less milk and raised calves that had higher genetic growth potential for WG. Further, the Pearson correlations between predicted breeding values of T and S with maternal WG indicated that animals with extremely large teats or pendulous udders may produce more milk, but that the calf may have trouble accessing it. Conversely, with extremely small teats or tight udders, smaller amounts of milk would be produced and there may be a problem producing enough milk to maintain the growing calfs maintenance requirements. Therefore, it may be more beneficial for producers to select animals that have intermediate breeding values for T and S.
Sapp
R L
RL
Animal and Dairy Science Department, University of Georgia, Athens 30602-2771, USA. rsapp@uga.edu
Rekaya
R
R
Bertrand
J K
JK
D000367:Age Factors; D000818:Animals; D000833:Animals, Suckling / Q000235:genetics / Q000254:growth & development*; D001835:Body Weight / Q000235:genetics; D001947:Breeding; D002417:Cattle / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D005260:Female; D008321:Mammary Glands, Animal / Q000033:anatomy & histology / Q000502:physiology*; D008957:Models, Genetic; D008962:Models, Theoretical; D010298:Parity; D019655:Quantitative Trait, Heritable; D012621:Seasons; D012641:Selection, Genetic; D012737:Sex Factors; D015430:Weight Gain / Q000235:genetics