RESUMO
The objective of this study was to evaluate the effects of strategic supplementation in the dry period and dry/rainy transition period on the performance and nutritional, metabolic, and reproductive responses of Nellore heifers grazing Urochloa decumbens. Forty-eight Nellore heifers with age and body weight (BW) of eight months and 235 ± 3.3 kg, respectively, were used. The experimental design was a completely randomized design, with four treatments, all with 12 replications. The evaluated strategies were as follows: low supplementation (LOHI; 0.2% of BW/heifer/day) in the first 90 days and high supplementation (0.6% of BW/heifer/day) in the 90 days thereafter; average supplementation (AVER) with 0.4% of BW/heifer/day for 180 days; high supplementation (HILO; 0.6% of BW/heifer/day) in the first 90 days and low supplementation (0.2% of BW/heifer/day) in the 90 days thereafter; only mineral mix (MM) ad libitum during the 180 days. Data were evaluated using orthogonal contrasts. Supplementation improved the performance of the animals during of dry period (P < 0.05) and dry/rainy transition period (P < 0.05). Supplemented animals had higher longissimus muscle area (LMA) and subcutaneous fat thickness (SFT) at the end of the experiment (P < 0.05). Multiple supplementation increased intake of dry matter (DM), organic matter (OM), and crude protein (CP) in kg/day throughout the experiment. The supplementation increased the digestibility of DM, OM, CP, apNDF, and TDN (P < 0.05). Serum urea nitrogen (SUN), glucose (GLUC), insulin (INS), and progesterone (PROG) were higher in supplemented heifers (P < 0.05). Supplementation reduced the concentrations of non-esterified fatty acids (NEFA) (P < 0.05) and increased conception rate (P < 0.05). In summary, the supplementation strategies adopted in this study improve the performance, metabolic status, and carcass traits of heifers under grazing, allowing an improvement in the conception rate of 15-month-old Nellore heifers.
Assuntos
Bovinos/fisiologia , Dieta/veterinária , Suplementos Nutricionais , Taxa de Gravidez , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Glicemia/metabolismo , Nitrogênio da Ureia Sanguínea , Peso Corporal , Ácidos Graxos não Esterificados/sangue , Feminino , Fertilização , Insulina/sangue , Nitrogênio/metabolismo , Poaceae/metabolismo , Gravidez , Progesterona/sangue , Distribuição Aleatória , Reprodução , DesmameRESUMO
The objective of this study was to evaluate the effects of supplementation strategy on performance, nutritional and metabolic characteristics of Nellore suckling female calves, on grazing Urochloa decumbens during the rainy-dry transition period. Forty-four Nellore female calves, averaging 147.6 ± 1.34 kg (4 months), were used. A single supplement 20% of crude protein of dry matter was provided, consisting of daily supplement at 0.0, 0.2, 0.4, or 0.6% of body weight. A positive linear effect (P < 0.05) on final body weight and average weight gain of female calves was observed with increased supplementation. Supplementation increased consumption, in kilograms per day, of dry matter (DM), organic matter (OM), crude protein (CP), digested dry matter, and total digestible nutrients (TDN), all calculated as % of dry matter. There was no effect of supplementation on the consumption in kilograms per day of neutral detergent fiber corrected for ash and protein (apNDF) (P > 0.05). Supplementation increased, in a quadratic way, the total apparent digestibility coefficient of DM, OM, CP, apNDF, and TDN (P < 0.05). There was no effect of supplementation (P > 0.05) on non-esterified fatty acid concentrations. There was a positive linear effect (P < 0.05) of supplementation on insulin concentrations. In this study, it is concluded that linearly increasing the feeding level of a supplement with 20% crude protein (% of DM) in the range of 0.2-0.6% of body weight improves the performance, nutritional and metabolic characteristics of the animals, considering these pasture characteristics.
Assuntos
Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Dieta/veterinária , Suplementos Nutricionais , Animais , Peso Corporal , Bovinos , Digestão/fisiologia , Feminino , Poaceae , Distribuição Aleatória , Clima Tropical , Aumento de PesoRESUMO
The objective of the present study was to evaluate the effect of different schemes of calves' supplementation in a creep feeding system, on the behavior of Bos indicus calves and dams, and also the influence of the calves' supplementation on dams' performance. Forty-eight Nellore male calves (147 ± 7 kg body weight and 3 months of age) in the suckling phase and their dams (476 ± 9 kg and 6 years of age) were studied in a completely randomized design. The experiment was divided into two periods of 71 days. The treatments were 5- and 10-g supplement dry matter (DM)/kg BW day offered in periods 1 and 2, respectively (5S/10S); 10- and 5-g supplement DM/kg BW day offered in periods 1 and 2, respectively (10S/5S); 7.5-g supplement DM/kg BW day in both periods 1 and 2 (7.5S); and mineral mix ad libitum in both periods 1 and 2 (MM). No differences (P < 0.05) in body condition score (BCS), final body weight (FBW), and average daily gain (ADG) were found in dams' performance. Calves from MM treatment spent more time (P < 0.05) grazing than the supplemented calves from 5S/10S and 10S/5S treatments, in the first period. No difference in suckling time was found between the treatments (P > 0.05) in the first evaluated period. Calves from 10S/5S treatment spent more time suckling and less time eating supplements (P < 0.05) than 5S/10S treatment animals, in the second evaluated period. Dams of MM treatment's calves had more idle time and lower grazing time when compared with the mothers of calves from 5S/10S and 10S/5S treatments. It was concluded that different schedules of Nellore calves' supplementation on pasture do not affect their mothers' performance, and supplementation decreases the grazing time of calves in the suckling phase.