Eficiência biológica de vacas de dois grupos genéticos amamentando bezerros puros ou F1, mantidas em diferentes condições de alimentação

The objective of the experiment was to evaluate the biologic efficiency of Charolais (CH) and Nellore (NE) cows nursing CH and ½NE ½CH (produced by CH cows), NE and ½CH ½NE (produced by NE cows) calves, mantained together until weaning, on native pasture (NP) or winter (oat + italian rye grass) and summer (alexander grass) cultivated pasture (CP). Cows and calves were weighted at birth; 14; 42; 70; 98; 126; 154; 182 days; and at weaning. The cows milk yield was evaluated at the same date of the calves weighing, with exception at birth. When the animals were mantained on CP, higher efficiency of converting the quantity of litres (EFLIT) (7.7 vs 11 L/kg) and dry matter (DM) (EFMS) of milk (1.06 vs 1.47 kg DM/kg) produced by cow into kg of calf weight gain, was observed. Quadratic effect of postpartum period for EFLIT (y=18.222-.141DAY+.000463DAY2) and EFMS (y=2.341-.0182DAY+.000063DAY2) was verified. Linear reduction of the daily requeriment of total digestible nutrients (mantainance plus milk production) (NDT) (NDT/day) was observed, as the lactation period advanced, for cows mantained on CP (.004 kg) and NP (.007 kg). The total requeriment (calving to weaning) of NDT (NDT/total) was superior for cows mantained on CP (1093.1 vs 1014 kg). However, cows mantained on CP were more efficient for transformation of NDT/dia (7.9 vs 12.5) and NDT/total (5.8 vs 8.2) in calf weight gain. The quantity of kg of calf produced/100 kg of cow (EFKG) (.201 vs .159 kg/100kg/day) and kg of calf produced per unit of cow metabolic weight (UTM) (EFTM) (.009 vs .007 kg/UTM/day) were higher when the cows were mantained on CP. Cows nursing F1 calves required more NDT/day (5 vs 4.8 kg/day). However, were more efficient for EFKG (27.1 vs 23.5 kg/100 kg) and EFTM (1.21 vs 1.05 kg/UTM). For cows nursing crossbred calves, the EFKG was higher for CH (28.5 vs 25.6 kg/100 kg). When EFTM was considered, higher value was observed for CH (1.11 kg/UTM) than for NE (.99 kg/UTM) cows, when they nursed straigthbred calves.

[1]  Leonir Luiz Pascoal,et al.  Efeito da pastagem, da produção e da composição do leite no desempenho de bezerros de diferentes grupos genéticos , 2004 .

[2]  Paulo Santana Pacheco,et al.  Grupo genético e nível nutricional pós-parto na produção e composição do leite de vacas de corte , 2003 .

[3]  I. Y. Mizubuti,et al.  Eficiência produtiva em vacas primíparas das raças Aberdeen Angus e Charolês , 2001 .

[4]  J. Restle,et al.  Efeito de grupo genético e heterose sobre a idade e peso à puberdade e sobre o desempenho reprodutivo de novilhas de corte , 1999 .

[5]  J. Restle,et al.  Effect of weaning age and pasture management on performance of beef cows and calves. 2. Performance of calves , 1994 .

[6]  J. Restle,et al.  DESEMPENHO EM CONFINAMENTOS DE NOVILHOS DE DIFERENTES GRUPOS GENÉTICOS , 1992 .

[7]  B. Freking,et al.  Interrelationships of heifer milk production and other biological traits with production efficiency to weaning. , 1992, Journal of animal science.

[8]  J. Restle,et al.  Desempenho de terneiros Charolês e Aberdeen Angus puros e seus mestiços com Nelore , 1991 .

[9]  J. Restle,et al.  Produção e composição do leite em vacas Charolês e Aberdeen Angus amamentando terneiros puros ou mestiços , 1991 .

[10]  G. Deutscher,et al.  Energy requirements for maintenance of crossbred beef cattle with different genetic potential for milk. , 1990, Journal of animal science.

[11]  D. D. Kress,et al.  Performance of crosses among Hereford, Angus and Simmental cattle with different levels of Simmental breeding: V. Calf production, milk production and reproduction of three- to eight-year-old dams. , 1990, Journal of animal science.

[12]  J. Altuna.  Resumen y conclusiones , 1984 .

[13]  C. Ferrell,et al.  Energy utilization by mature, nonpregnant, nonlactating cows of different types. , 1984, Journal of animal science.

[14]  J. Holloway,et al.  Utilization of Forage and Milk Energy by Angus Calves Grazing Fescue or Fescue-Legume Pastures , 1982 .

[15]  D. Boggs,et al.  Effects of milk and forage intake on calf performance. , 1980 .

[16]  O. W. Robison,et al.  Milk Production in Hereford Cows I. Means and Correlations , 1978 .

[17]  R. Wyatt,et al.  Effect of Milk Level and Biological Type on Calf Growth and Performance2 , 1977 .

[18]  R. Totusek,et al.  Relation of Estimation Method, Sampling Interval and Milk Composition to Milk Yield of Beef Cows and Calf Gain , 1973 .

[19]  J. Bond,et al.  Effect of energy and protein on estrus, conception rate, growth and milk production of beef females. , 1970, Journal of animal science.

[20]  J. K. Riggs,et al.  Milk Production, Composition and Calf Gains of Angus, Charolais and Hereford Cows , 1967 .

[21]  W. E. Neville.  Influence of dam's milk production and other factors on 120- and 240-day weight of Hereford calves. , 1962 .

[22]  C. J. Brown,et al.  Relationships among Factors Associated with Mothering Ability in Beef Cattle , 1959 .