Dairy cattle cross-breeding in the tropics: Performance of secondary cross-bred populations

Breed group effects on milk production of Brazilian crossbred dairy cows.

Data from 1,456 purebred Mashona calves were analysed to determine environmental influences on growth rate and liveweight at birth, weaning (205 days) and 18 months of age Calves were born between mid-September and mid-December each year Year of birth was highly significant for all traits (P<0001) Pre-weaning liveweight and weight gain increased as age of dam increased to seven years after which growth tended to decline Post-weaning compensatory growth was apparent in calves of young dams Male calves grew faster and were heavier at all stages than female calves (P<0001) Calves from previously non-lactating cows grew more rapidly and were heavier at all ages than those from previously lactating cows Birth weight increased as calving season advanced and calves born late maintained their growth advantage until 18 months of age The results indicate that environmental influences experienced in early life persist long after weaning

Growth of Mashona cattle on range in Zimbabwe. I. Environmental influences on liveweight and weight gain.

The productive performance of four Holstein-Gir genetic groups (1/2H, 1/4H, 5/8H, 5/8Hinter se) and the effects of non-genetic factors on production traits was evaluated using a data set of 7,951 test-day samples collected between January 1980 and December 1999 from the Arcoverde Experimental Station in the Brazilian state of Pernambuco (Empresa Pernambucana de Pesquisa Agropecuaria). The statistical model included the fixed effects of calving year (1980 to 1999) and month (January to December), genetic group of the cow, age at months of calving (33 to 190) and days in milk at each test-day. Random effects were sire, cow and residual with test-days treated as repeated records within each cow within each lactation. For the four genetic groups the milk yield (MY) means were 1/2H = 8.61 kg ± 1.16 kg, 1/4H = 5.34 kg ± 0.46 kg, 5/8H = 7.42 kg ± 0.39 kg and 5/8Hinter se = 5.76 kg ± 0.46 kg; the fat yield (FY) means were 1/2H = 0.375 kg ± 0.052 kg, 1/4H = 0.231 kg ± 0.026 kg, 5/8H = 0.299 kg ± 0.025 kg and 5/8Hinter se = 0.231 kg ± 0.026 kg; and the fat percentage (FP) means were 1/2H = 4.45 kg ± 0.29%, 1/4H = 4.08 kg ± 0.12%, 5/8H = 3.87 kg ± 0.10% and 5/8Hinter se = 3.89 kg ± 0.12%. Phenotypic correlations between tests were MY = 0.97, FY = 0.94 and FP = 0.98. The best productive performance was for the 1/2H group, followed by the 5/8H group. The performance of the synthetic group was substantially below the performance of the 5/8H group.

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Milk and fat production of crossbred Holstein-Gir cows (Bos taurus taurus-Bos taurus indicus) in the agreste region of the Brazilian state of Pernambuco

Reapeatability of productive traits in Egyptian buffaloes

Data from 5270 lactation records of 1380 cows sired by 132 bulls and recorded from 1962 to 1977 were analysed. Statistical analyses, using least squares and maximum likelihood methods, showed significant effects for genetic group, age of cow, month and year of calving, and lactation length. Overall mean milk yield was 2780 kg (CV = 0·31) with mean lactation length of 281 days. Maximum production occurred in the fifth lactation (104 or 105 months of age at calving) with a yield of 1·3 times that of the first lactation. Repeatability estimated by intraclass correlation was 0·40 (s.e. 0·03). Heritability estimated from paternal half-sib correlation was 0·16 (s.e. 0·06). Overall results were very similar to those obtained from research with European breeds in temperate areas.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0003356100041787

A. A. M. Gonçalves

Papers

Genetic and environmental effects on milk yield of Pitangueiras cattle