a b s t r a c tThe objective of this work was to evaluate carbon turnover and half-life in feces and blood from sheep fed on C 3 and C 4 plant diets, using the stable isotope technique. Eight Santa Ines sheep were randomly distributed between two treatments: the first consisted of animals that were fed alfalfa hay, and the second consisted of animals that were fed corn silage only. Function of time was used to measure carbon turnover rate. At steady state, the half life for carbon isotopic enrichment between food and feces is 1.2 and 1.0 days for alfalfa hay and corn silage treatments, respectively. For blood data collection the time was insufficient to reach the isotope equilibrium level, indicating a slow carbon exchange between diet and blood. It is concluded that blood has a slow turnover, indicating the isotope signal for the former diets. Feces, by contrast, have a quick turnover, indicative of their recent diets.
This study consisted of two experiments with the following objectives: to evaluate the effects of tannins from the tropical legume macrotiloma (Macrotyloma axillare) on total gas and methane (CH ) production, as well as on ruminal fermentation parameters by performing an in vitro bioassay, with samples incubated with and without polyethylene glycol (PEG) in a semi-automatic system; and secondly in a 17 day in vivo experiment, to determine apparent total tract digestibility (ATTD) of dietary nutrients and ruminal fermentation parameters of 12 intact 8- to 9-month-old Santa Inês (averaging 24.95 ± 1.8 kg body weight) ewes fed tropical grass hay supplemented with macrotiloma hay. The ewes were divided into two treatment groups depending on their diet: chopped aruana grass hay (Panicum maximum cv. Aruana) (control-CON); and aruana grass hay supplemented with chopped macrotiloma hay (macrotiloma-MAC). The animals were kept for 5 consecutive days in metabolic cages for the ATTD assay, and at the end of this period, samples of rumen fluid were collected from each ewe to determine ammoniacal nitrogen (NH -N) and short-chain fatty acid (SCFA) production, and protozoa count. For the in vitro assay, a decrease in total gas and CH production was observed for samples incubated without PEG (p < .05). No differences were observed for the other parameters evaluated (p > .05). In the in vivo experiment, increased intake and ATTD of crude protein were observed for the animals fed MAC when compared to CON (p < .05). For rumen fermentation parameters, increased NH -N, total SCFA and isobutyrate concentrations, as well as reduced protozoa count were observed for MAC when compared to CON (p < .05). The results observed here indicated the potential of macrotiloma for use as a ruminant feed, and antimethanogenic potential of this plant was noted.
RESUMO Desempenho, características de carcaça e custos da terminação de cordeiros Suffolk em sistemas com desmame precoce e amamentação controladaO objetivo deste trabalho foi avaliar o desempenho, as características de carcaça e os custos da terminação de cordeiros Suffolk em três sistemas: (1) cordeiros desmamados com 22 kg de peso corporal (PC) e mantidos em pastagem com suplementação concentrada até o abate; (2) cordeiros desmamados com 22 kg de PC e confinados até o abate; (3) cordeiros mantidos em amamentação controlada após atingirem 22 kg de PC e confinados com alimentação em creep feeding até o abate. Os valores de ganho médio diário (GMD) foram 224 g/dia para os cordeiros desmamados e suplementados em pastagem; 386 g/dia para os cordeiros desmamados e confinados, e 481 g/dia para os cordeiros mantidos em amamentação controlada. O peso de corpo vazio e a deposição de gordura visceral foram maiores em The performance, carcass traits and finishing costs of Suffolk lambs were evaluated in three systems: (1) lambs weaned with 22 kg of body weight (BW) and supplemented with concentrate on pasture until slaughter; (2) lambs weaned with 22 kg BW and fed in feedlot until slaughter; (3) lambs maintained in controlled nursing after 22 kg BW and creep fed in feedlot until slaughter. Average daily gain (ADG) was 224 g/d for lambs weaned and supplemented with concentrate on pasture, 386 g/d for lambs weaned in feedlot and 481 g/d for lambs under controlled nursing. Empty body weight and visceral fat deposition were highest in lambs from feedlot systems. Carcass weights and carcass yields were highest for lambs in controlled nursing. Finishing total costs were highest in controlled nursing and lowest in the system with weaning in feedlot. High concentrate diet associated with controlled nursing in feedlot allowed lambs to reach the growth potential and carcasses with higher weights, higher yields and higher fat content. After weaning, lambs in feedlot fed with high concentrate diet had higher weight gain than lambs supplemented with concentrate on pasture. Carcasses produced under these two systems presented the same characteristics. The system with weaning in feedlot showed the lowest cost per kg carcass.
The objective of this study was to evaluate the effects of using encapsulated nitrate product (ENP) replacing soybean meal in diets differing in concentrate to forage ratio on ruminal fermentation and methane production in vitro using a semi‐automatic gas production technique. Eight treatments were used in a randomized complete design with a 2 × 4 factorial arrangement: two diet (20C:80F and 80C:20F concentrate to forage ratio) and four levels of ENP addition (0%, 1.5%, 3.0%, and 4.5% of DM) replacing soybean meal. There was a diet × ENP interaction (p = 0.02) for methane production. According to ENP addition, diets with 80C:20F showed more intense reduction on methane production that 20C:80F. A negative linear effect was observed for propionate production with ENP addition in diet with 80C:20F and to the relative abundance of methanogens Archaea, in both diet. The replacement of soybean meal by ENP in levels up to 3% of DM inhibited methane production due to a reduction in the methanogens community without affecting the organic matter degradability. However, ENP at 4.5% of DM level affected fiber degradability, abundance of cellulolytic bacteria, and propionic acid production, indicating that this level of inclusion is not recommended for ruminant production.
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