Performance, metabolic and hormonal responses on peripartum of grazing beef cattle supplemented on pre-partum

• Ano de defesa: 2018
• Autor(a) principal: Ferreira, Matheus Fellipe de Lana
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Bovinos - Nutrição; Bovinos - Gestação; Nelore (Bovino); Bovinos - Fisiologia; Produção Animal
• Link de acesso: http://www.locus.ufv.br/handle/123456789/21058

Nutritional status at calving is the main factor affecting time to pregnancy. Metabolic parameters that relate nutritional status to physiological processes within grazing animals, mainly Zebu, are not fully understood. This study evaluated the effects of 60-day pre-partum energetic-protein supplementation on performance, metabolic and hormonal responses on peripartum of grazing beef cattle. Thirty-eight Nellore multiparous cows averaging 230 ± 10 days of gestation were used. Two treatments were evaluated: control, without supplementation and daily supplementation (30% of CP) with 1.5 kg during the 60 days before expected calving. The experiment was carried out according to completely randomized design. It was calculated the average daily gain pre-calving and post- calving. The calves were weighted at 45 and 90 days. Body condition scores (BCS) were also recorded at the beginning of the experiment, at calving and 45 days post-partum. Every 30 days grass samples were collected by hand plucked sampling and collected cutting at ground level. To evaluate intake and digestibility, a trial was performed at 45 days before the estimated date of parturition. It was used titanium dioxide (TiO2) to estimate the fecal excretion of animals and indigestible neutral detergent fiber (iNDF) to estimate the pasture dry matter intake (DMI). It was assumed that the supplement consumption will be equal to the quantity offered per animal/day. At last day of the trial, spot urine samples were collected 4 hours before and after the supplement offer. At the 30 and 45 days post-calving, were performed milking to estimate the milk production. Taking calving day as day 0, blood samples were collected before supplementation on days -30, 0, 15, 30, 45 by jugular vein puncture, using vacuum tubes to quantity glucose, blood nitrogen urea (BUN), total protein, albumin, triglycerides, total cholesterol, high density lipoprotein (HDL), non- esterified fatty acid (NEFA), beta-hydroxybutyrate (βHB), insulin, insulin-like growth factor (IGF-1), total triiodothyronine (T3), total thyroxine (T4) and progesterone (P4) contents. It was calculated the pregnancy rate and number of days from calving to conception. ADG was higher at pre-partum (P<0.10) for supplemented cows but did no differ at post-partum period (P>0.10). Supplementation did not affect (P>0.10) BCS and calves’ BW at calving, and at 45 and 90 days. There was no effect of supplementation on milk yield and composition (P>0.10). There were no differences (P>0.10) with regard forage intake and neutral detergent fiber digestibility. The intake and digestibility of CP and OM increased (P<0.10) with supplementation. Supplementation had no effect (P>0.10) regards serum concentration of metabolites and hormones. Concentration of these variables changed significantly (P<0.10) along the days relative to calving. There was no difference on pregnancy rate and, days from calving to conception among treatments (P>0.10). Under these circumstances, providing 1.5 kg of energetic-protein supplement during the last 60 days of gestation do not improve performance, metabolic and hormonal responses in grazing Nellore cows.