Recria de bezerras com suplementação no outono e pastagem cultivada no inverno Rearing beef heifers with supplementation in the fall and cultivated pasture in the winter

Avaliou-se o desenvolvimento de bezerras de corte de diferentes rebanhos submetidas no pós-desmame a níveis de suplementação em pastagem nativa no outono e em pastejo em aveia preta (Avena strigosa Schreb) e azevém (Lolium multiflorum Lam) durante o inverno, em um período total de 135 dias. Foram utilizadas 118 bezerras com sete meses de idade em maio de 2003, provenientes de três rebanhos distintos: R1 e R2 - bezerras Aberdeen Angus; RG - bezerras mestiças Aberdeen Angus. Os níveis de suplementação foram 0,7; 1,0 e 1,3% do PV. Na pastagem cultivada os animais ficaram em grupo único. Foram avaliados o PV, a condição corporal (CC), o ganho de peso médio diário (GMD), o ganho de condição corporal (GCC) e o crescimento relativo (CR). Não houve interação níveis de suplementação <FONT FACE=Symbol>&acute;</FONT> rebanho. Durante o outono em pastagem nativa, as bezerras suplementadas com 1,3% do PV tiveram maior GMD (0,405 kg) em relação às de 0,7% do PV (0,300 kg). Na pastagem cultivada, o GMD não diferiu entre os níveis de suplementação do outono, com média de 0,820 kg. Considerando os diferentes rebanhos, os animais RG tiveram sempre PV e CC superiores aos demais. As bezerras do R1, com menor PV e CC inicial, igualaram-se às do R2 ao final do período hibernal. As bezerras R1 tiveram maior CR (77,1% do PV e 32,4% da CC) em relação as do R2 e RG, as quais tiveram em média 57,1% do PV e 14,7% da CC. As variáveis PV e CC iniciais foram altamente correlacionadas (r=0,811), entretanto, não tiveram correlação com GMD durante a recria. O PV e a CC final foram determinados pelo PV inicial e pelo GMD durante a recria. As bezerras mais pesadas à desmama não foram necessariamente as mais pesadas aos 12/13 meses de idade.<br>This trial evaluated the effects of different levels of supplementation on the growth of weaned female beef calves grazing native pasture during the fall. Development of these same animals grazing pastures of black oat (Avena strigosa Schreb) and annual ryegrass (Lolium multiflorum Lam) during the winter were also investigated. One hundred-eighteen female calves averaging seven months of age from three distinct herds: H1 and H2 (Aberdeen Angus animals) and H3 (crossbred Aberdeen Angus animals) were used. Calves grazing the native pasture were supplemented with a commercial concentrate as follows: 0.7, 1.0 or 1.3% of body weight (BW). During the winter, animals were moved to pastures of black oat and annual ryegrass and were all maintained in the same group. The following measurements were taken: BW, body condition (BC), average daily gain (ADG), body condition gain (BCG), and relative growth (RG). No significant supplementation levels <FONT FACE=Symbol>&acute;</FONT> herd interactions were detected. Animals grazing native pasture supplemented with 1.3% BW as concentrate had greater ADG (0.405 kg) than those supplemented with 0.7% BW (0.300 kg). The ADG of animals grazing black oat and annual ryegrass did not differ and averaged 0.820 kg. Within the three herds, animals from H3 had greater BW and BC than those from H1 and H2. Calves from H1 with lower initial BW and BC showed compensatory growth and had similar BW and BC compared to H2 calves at the end of the winter period. H1 calves had higher RG (77.1% of BW and 32.4% of BC) than H2 and H3 calves, which averaged 57.1% of BW and 14.7% of BC. Initial BW and BC were highly correlated (r=0.811) but both were not correlated with ADG during rearing. The final BW and BC were affected by initial BW and ADG during rearing. Calves with the greatest BW at weaning were not always the heaviest animals at one year of age.