Revista Brasileira de Zootecnia | |
Comparative Performance of Six Holstein-Friesian/Guzera Crossbred Groups. 11. Weight and Height of Cows and Heifers | |
Madureira, Ana Paula2  Madalena, Fernando Enrique2  Teodoro, Roberto Luiz1  | |
[1] EMBRAPA Gado de Leite;UFMG | |
关键词: liveweight; withers height; crossbred cows; heterosis; crossbreeding IntroduçãoO peso corporal é importante componente da eficiência da produção de gado de leite; já que mais de 50% das exigências de energia total podem ser atribuídos à mantença (Cue et al; | |
DOI : 10.1590/S1516-35982002000300016 | |
学科分类:兽医学 | |
来源: Universidade Federal de Vicosa | |
【 摘 要 】
- Weight, height at withers and the weight/height ratio (an indicator of body condition) of respectively, 263, 232 and 232 cows and 171, 135 and 135 heifers were studied. Animals were of six red and white Holstein-Friesian (HF) x Guzerá (Guz) crosses: ¼, ½, 5/8, ¾, 7/8 and ³ 31/32 HF. Model [1] for cows included the fixed effects of reproductive status, days in milk, season when weighted, farm class, age and genetic group, two-factor interactions and the random effect of cow, and for heifers the fixed effects of season, farm class, age and genetic group, the season x age interaction and the random effect of heifer. Model [2] was the same as model [1] except that the regressions on HF fraction and breed heterozygocity substituted for the genetic group classification effect, to estimate the breed additive difference (gI, HF-Guz) and heterosis (hI). Height of cows or heifers did not show heterosis but declined linearly with the HF fraction (cows, gI = -9.75+2.42 cm, heifers, -10.38+2.72 cm). In both categories, the liveweight gI estimates did not significantly differ from zero, while heterosis was very important (hI = 51.42+13.40 kg in cows and hI = 109.77+ 32.97 kg in heifers). For weight/height the respective estimates in cows and heifers were gI = 0.27+0.10 and 0.41+0.24 kg/cm and hI = 0.36+0.08 and 0.65+0.24 kg/cm. F-tests on the extra variation due to fitting model [1] after model [2] were not significant, indicating that epistasis or other genetic effects not included in model [2] were of little importance. The heaviest cross was the F1, which also showed the highest weight/height ratio.
【 授权许可】
CC BY-NC
【 预 览 】
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