Supplementation strategies affect feed intake and performance of grazing holstein heifers

• Ano de defesa: 2018
• Autor(a) principal: Machado, Wagner da Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Novilhos - Alimentação e rações; Proteínas na nutrição animal; Metabolismo energético; Suplementos dietético; Novilhos - Registros de desempenho; Produção Animal
• Link de acesso: http://www.locus.ufv.br/handle/123456789/20163

Literature lacks studies investigating performance of grazing Holstein heifers on tropical conditions, under different supplementation regime. Thus, we aimed to evaluate intake, performance and digestibility of grazing Holstein heifers under 3 supplementation strategies during the rainy and rainy-dry transition seasons. Eighteen Holstein heifers with average age and initial live weight of 12.57 ±2.54 mo and 218.76 ±47.6 kg, respectively were submitted to a randomized block design, with 6 replicates on a rotational grazing system of Panicum maximum cv. Mombaça pasture. Treatments were: control (CON; mineral salt ad libitum); energy supplement (ENE; corn meal as supplement); and protein supplement PRO (corn and soybean meal, 25% crude protein (CP)). Supplements were fed at 0.5% BW. The experiment lasted 120 days subdivided into 3 periods. Titanium dioxide and indigestible neutral detergent fiber (iNDF) were used to estimate intakes and digestibility of the nutrients. Body weight, withers height, thoracic circumference, body length, and ultrasound of ribeye area, and ribeye fat thickness measurements were taken every period. Body condition scores (BCS) was taken twice. MIXED procedure of SAS including period as repeated measurements was used and significance was declared at P ≤ 0.05. DM intake, CP intake (CPI) and DE intake were greater in PRO (P<0.05) compared to CON and ENE. Supplementation strategy affected forage DM intake (%BW, P = 0.049), and a supplementation strategy × period interaction was observed for NDF intake (%BW), mainly due to a greater NDFI/BW in the period 3 to CON. The PRO had greater (P<0.05) grass DM digestibility compared to CON. ENE had lower CP digestibility compared to PRO and CON (P<0.01). Average daily gain (ADG) and thoracic circumference gain were the greatest (P<0.05) in PRO. BCS was greater (P = 0.02) on PRO (3.43) than CON (3.24) and ENE (3.03). PRO animals had the best performance, consequently they better expressed the associative effects of forage and supplement. Its recommended that Holstein heifers in rotational grazing system with Mombaça grass should be protein supplemented during the rainy and rainy-dry transition seasons to maximize performance. vi