Suplementação de bovinos de corte em pastejo com diferentes relações proteína: carboidrato da fase de amamentação ao abate

• Autor(a) principal: Valente, ériton Egidio Lisboa
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1814
• topic: Suplementação; Bovinos de corte; Proteína; Carboidrato; Supplementation; Beef cattle; Protein; Carbohydrate; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

It was elaborated 5 articles relate with supplementation of grazing beef cattle with different relation protein: carbohydrate. The aim of article 1 was evaluate the effects of supplementation of beef calves on weight gain, intake and digestibility of pasture, milk production and composition of their dams and behavior of the pair cowcalf. Fifty-five beef cows (449 ± 8 kg) and their respective offspring, (138 ± 3kg and 90 -150 days) were used. Animals were submitted to an experimental period of 112-days. The experimental treatments consisted of: Control= mineral mixture only; HPHC= high protein and high carbohydrate supplement; HPLC = high protein and low carbohydrate supplement; LPHC = low protein and high carbohydrate supplement; LPLC = low protein and low carbohydrate supplement. About 25% and 12.5% of the protein requirements were supplied by the high and low protein supplements respectively, and 15% and 7.5% of total digestible nutrients (TDN) requirements by the high and low carbohydrate supplements respectively. Grazing behavior, performance, milk production, milk composition, intake and digestibility of the cows were not affected (P>0.05) by the supplementation of the calves. The supplemented calves had greater (P<0.05) performance (as measured by final body weight, average daily gain and final body condition score), intake and idle time, and lower (P<0.05) grazing time, but supplementation did not affect (P>0.05) suckling time and suckling frequency. It can be concluded in the article 1 that supplementation affects the behavior and feed intake of calves. However, it does not affect the suckling time and suckling frequency of calves. Additionally, performance, milk production, nutritional characteristics and behavior of their dams are not affected. In the article 2, the objective was evaluate the effects of supplementation with different relations of carbohydrate and protein on performance of young bull from 4 until 18 months were assessed. Fifty-five beef calves with average initial body weight of 138.3±3.4 kg and age between 90 and 150 days were used. Animals were submitted to a 430-days experimental period. The experimental treatments consisted of: Control= mineral mixture only; HPHC= high protein and high carbohydrate supplement; HPLC= high protein and low carbohydrate supplement; LPHC= low protein and high carbohydrate supplement; LPLC= low protein and low carbohydrate supplement. The amount of supplement was adjusted every 28 days. The non-supplemented animals presented lower (P<0.05) average daily gain (ADG) than supplemented animals. Non-supplemented animals presented lower (P<0.05) DM intake than supplemented animals in the dry season. However, in the rainy period, differences were not observed (P>0.05) in DM intake. Nutritionals plans with low supply of carbohydrate (HPLC and LPLC) presented greater supplement use efficiency. It can be concluded in the article 2 that supplementation increase performance of young bulls belong the productive cycle. However, nutritional plans that supply low amount of carbohydrate (until 15% of TDN requirement) have greater efficiency of supplement use. The article 3 aimed evaluate the intake and digestibility of young bulls supplemented with different ratios of protein: carbohydrates in tropical pastures from 4 until 18 months. The methodology was the same of the article 2. Dry matter (DM) intake was higher (P<0.05) in dry to rain transition and rain seasons for all nutritional plans. Non-supplemented calves had lower (P<0.05) intake of DM and total digestible nutrients (TDN) than supplemented calves in all seasons with exception in rain season. Although differences on DM intake was not observed (P>0.05) between supplemented animals, the supplements with high carbohydrate (HPHC and LPHC) had lower (P<0.05) forage intake (P<0.05) in the suckling phase (rain to dry transition season) and in the rain season. However, the HPHC plan had higher (P<0.05) intake and digestibility of neutral detergent fiber. It can be concluded in the article 3 that the effects of supplementation type on nutrition characteristics suffer interaction with season. Supplement with high protein level (supplying 50% CP requirement) increase intake and digestibility of diet, being more intense when associate with high carbohydrate level (supplying 30% TDN requirement). On other hand, supplement with low protein level (supplying 25% CP requirement) and high carbohydrate level decrease DM intake and fiber digestibility, occurring more intense in rainy season. The objective of the article 4 was to compare visual observation and an electronic grazing time method and to evaluate the effects of nutritional plans in intake, grazing behavior and horizontal and vertical locomotion of young bulls in a tropical pasture. Thirty-nine Nellore young bulls with an average body weight of 345 ± 9.3 kg were used. The experimental treatments consisted of: restricted: animals housed in a plot with a low mass of forage receiving mineral mixture only; and nutritional plans described in the article 2. GPS Collars equipped with activity sensors were used. Information about head position, latitude, longitude and altitude were recorded. Daytime grazing behavioral patterns monitored by a continuous focal animal recording method was compared to behavior estimated by the activity sensor. Feed intake was measured by a marker method. The Restricted group presented lower (P<0.05) intake of dry matter and TDN. However, differences were not found (P>0.05) between non-supplemented and supplemented animals. Differences were not found (P>0.05) in daytime grazing time obtained by visual observation or the activity sensor method. The restricted group showed longer (P<0.05) grazing times (9.58 hours/day), but differences were not found (P>0.05) in the grazing times between Control (8.35 hours/day) and supplemented animals (8.03 hours/day). The Restricted group presented lower (P<0.05) horizontal locomotion distance (2168 m/day) in comparison to other groups (2580.6 m/day). It can be concluded in article 4 that the use of activity sensor methods is recommended due to being able to record 24-hours. While supplements with high carbohydrates reduce pasture intake, they have not changed grazing behavior. Moderate supplementation (until 50% of protein requirement and 30% of energy requirement) of beef cattle on tropical pasture has not effect on daily locomotion. The aim of the article 5 was estimate protein and energy requirement of beef cattle on tropical pastures from 4 until 18 months. Forty-six beef calves (138.3±3.4 kg of BW and 90-150 days of age) housed in signal grass pasture were used. The treatments were the same of described in the article 4. The net energy requirement for weight gain (NEg) was obtained by linear regression of logarithm of retained energy in function of logarithm of empty body weight gain. The net energy requirement for maintenance (NEm) was estimated by exponential relation between heat production (kcal/EBW0.75/day) and metabolizable energy intake. The net protein requirement for weight gain (RP) was estimated by multiple linear regression of retained protein in the weight gain of empty body and retained energy. The efficiency of metabolizable energy (ME) for maintenance (km) was 0.55 and for weight gain was 0.26. The ME requirement for maintenance was 124 kcal/EBW0.75/day, 11% higher than the requirement for feedlot cattle in Brazil. The RP decreased with increase of body weight. The NEg and RP may be obtained by equations: RE (Mcal/kg) = 0.044 x EBW0.75 x EBWG1.1302, RP (g/day) = -31.45 + 229.69 x EBWG 8.75 x RE, respectively.