Behavior, performance, and tick incidence in Girolando and Holstein grazing heifers

• Ano de defesa: 2019
• Autor(a) principal: Villanova, Daiana Francisca Quirino
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Zootecnia
• Palavras-chave em Português: Bovino de leite - Registros de desempenho; Panicum maximum; Pastejo; Nutrição e Alimentação Animal
• Link de acesso: https://locus.ufv.br//handle/123456789/30385

Performance studies on young dairy cattle in tropical pastures are still deficient in literature, mainly studies comparing different breeds. The aim of this study was to evaluate the behavior, performance and tick incidence in Girolando and Holstein heifers in intermittent grazing system in Guinea grass (Panicum maximum Jacq. cv Mombaça). Sixteen heifers were divided in two groups according to body weight (BW), one with 258.6 ± 24.79 kg and other with 157.1 ± 24.99 kg. Each group consisted of 4 Girolando (½ Holstein × ½ Gyr) and 4 Holstein heifers. The experimental period lasted 84 d subdivided into 4 periods. To estimate the average daily gain (ADG), animals were weighing at beginning and at end of experiment. The counting and collection of ticks were out carried each period. Behavior analyzes were performed during 48 h with observations every 10 min. The behavioral variables considered were: ruminating, grazing, resting, and concentrate intake time. For digestibility analyzes, titanium dioxide was used to estimate concentrate intake, chromic oxide to estimate fecal excretion and FDNi as internal marker to estimate forage intake. Samples were collected to estimate dry matter (DM), crude protein (CP), ether extract (EE), ashes, neutral detergent fiber (NDF) and indigestible NDF (iNDF). Blood samples were taken at the end of experiment to evaluate the blood concentrations of glucose (G), urea (U), total protein (TP), albumin (Alb), insulin-like growth factor 1 (IGF- 1), triiodothyronine (T3), and thyroxine (T4). Statistical analyzes were performed using the GLIMMIX SAS procedure and differences were considered when P values <0.05, and values 0.05 < P < 0.10 were considered as trend. Differences were observed for forage intake (FDMI) and NDF intake, both with greater values to Girolando heifers. We observed a trend to greater concentrate intake to Holstein heifers. Holstein animals tended to have a greater DMI/BW. We observed a trend of greater digestibility of CP and NDF to Girolando heifers. The ADG was greater to Girolando heifers, as well as feed efficiency. The rumination time was greater to Girolando heifers, while resting time was greater to Holstein heifers. The concentrate intake time was also greater for Holstein heifers. The tick count and weight was greater for Holstein. Blood concentrations of U, Alb, IGF-1, T3 and T4 were greater to Girolando heifers. The greatest Girolando animals’ performance might be related to better nutrients use from forage due greater forage intake and greater rumination time. It is possible that Holstein animals suffered heat stress, impairing their performance.