Wbeimar Yamit Sanchez Dueñez

Resumo Este manuscrito objetiva trazer informações globais sobre a produção de bezerros de origem leiteira para corte em confinamento, abordando aspectos como raça, sexo, idade, peso, consumo, digestibilidade, parâmetros ruminais, desempenho e características da carcaça, entre outros aspectos importantes, com base em artigos científicos e teses contendo dados atuais e relevantes. Incrementos da produção de leite no mundo e a utilização de novas tecnologias como seleção de raças com aptidão para produção de leite além dos importantes avanços no desempenho desses rebanhos, tem incrementado a oferta de bezerros machos leiteiros. Com exceção do uso desses animais para fins reprodutivos, a manutenção de touros leiteiros em fazendas de laticínios seria justificada se eles fossem destinados à produção de carne. Segundo a literatura consultada, o confinamento e a produção precoce com dietas de alto grão ou com alto conteúdo energético são as principais propostas de criação desses tipos de animais que é bem conhecido que esses bezerros não conseguem se adaptar as condições extensivas em comparação com raças especializadas para produção de carne. Também aspectos como requerimentos nutricionais, parâmetros ruminais e de desempenho vêm sendo estudados tanto na desmama, recria e terminação de bezerros de origem leiteira. Nesse sentido, vários trabalhos demonstram a relevância da criação e da adoção de bezerros de origem leiteira como uma fonte de proteína animal e apontam resultados de viabilidade econômica positivos, propondo então o aproveitamento por parte dos produtores com a finalidade de gerar renda extra para as fazendas.

This manuscript aims to provide comprehensive information on the production of dairy calves for beef in feedlot systems, addressing aspects such as breed, age, weight, intake, digestibility, ruminal parameters, performance, and carcass characteristics, among other relevant factors, based on a systematic review of scientific articles and theses containing current and pertinent data. Increases in global milk production and the use of new technologies, such as the selection of breeds with aptitude for milk production, along with significant advances in herd performance, have increased the supply of male dairy calves. Except for using these animals for reproductive purposes, the maintenence of dairy bulls on dairy farms would be justified if they were intended for meat production. According to the literature consulted, feedlot rearing and early production using high-energy diets are the main strategies for raising these animals, since it is well known that dairy calves cannot adapt to extensive systems as well as breeds specialized in meat production. Aspects such as nutritional requirements, ruminal parameters, and performance have also been studied during the pre-weaning, weaning, post-weaning, and finishing phases of dairy calves. In this context, several studies demonstrate the relevance of raising dairy calves as a source of animal protein and report positive results regarding their economic viability, thereby proposing their use as a means for producers to generate additional farm income.

The objective of this study to evaluate the effects of two levels of concentrate supplementation (1 g/kg or 2 g/kg of body weight, BW) on the intake, apparent digestibility and performance of Girolando steers on tropical pastures during the post-weaning phase in the dry to rainy season transition. We used 20 Girolando steers (half Holstein x half Zebu), with an average initial BW of 151.15 ± 50 kg and 12 months of age. The steers grazed on Urochloa brizantha cv. Marandu pasture. The animals were randomly assigned supplementation with 1 g/kg of BW (SC1) or supplementation with 2 g/kg of BW (SC2) of a concentrate supplement. The forage dry matter intake (%BW), neutral detergent fiber intake (NDF) and NDF digestibility were higher (p < 0.05) for steers supplemented with a level of 1 g/kg of BW. Supplement intake (kg/day), non-fibrous carbohydrate (NFC) intake and NFC digestibility were higher (p < 0.05) for steers consuming 2 g/kg BW of the concentrated supplement. The body weight at slaughter (297 kg) and average daily gain (0.57 kg/day) were not influenced by the level of supplementation. The use of 1 g/kg BW of a concentrated supplement is recommended for post-weaning steers on tropical pastures during the dry to rainy season transition.

The study aimed to evaluate the effects of three supplementation strategies on intake, apparent digestibility, feeding behavior, performance, carcass traits, proximate composition, and the fatty acid profile of meat from steers on tropical pasture during the post-weaning and finishing stages. The experiment involved 33 1/2 Holstein × 1/2 castrated Zebu steers weighing 335 ± 42.90 kg, aged 22 ± 2 m. The animals were managed on Urochloa brizantha cv. Marandu using an intermittent grazing system with continuous stocking and variable stocking rates for 310 days. The supplementation strategies were as follows: MS/US (mineral salt/urea supplementation): mineral salt in the rainy season and mineral salt with urea in the dry season; US/PS1 (urea supplementation/protein supplementation): mineral salt with urea in the rainy season and protein supplement at 1 g/kg body weight (BW) in the dry season; and PS1/PS2 (protein supplementation 1/protein supplementation 2): protein supplement at 1 g/kg BW in the rainy season and 2 g/kg BW in the dry season. The dry matter intake did not differ significantly (p > 0.05) between strategies. However, the post-weaning PS1/PS2 strategy resulted in higher (p < 0.05) crude protein intake. The final body weight did not differ (p > 0.05) between the strategies, but the average daily gain in post-weaning and finishing was higher (p < 0.05) for MS/US (restricted) animals. Carcass weight, subcutaneous fat thickness, and lipid content in meat were significantly higher (p < 0.05) for steers in the PS1/PS2 group. Steers finished on MS/US produced meat with a higher content of polyunsaturated fatty acids and ω-3 fatty acids (p < 0.05). Concentrate supplementation at 1 g/kg BW during the rainy season and 2 g/kg BW during the dry season is recommended for post-weaning and finishing steers on tropical pasture.