Grazing strategies promote changes in sward structure that can affect patterns of herbage accumulation and sward flexibility to management. This experiment evaluated sward structural characteristics and herbage accumulation of Mombaça guinea grass (Panicum maximum Jacq. cv. Mombaça) subjected to rotational stocking managements. Treatments involved grazing when swards reached either 95 or 100% interception of the incident light (LI), to post-grazing heights of 30 and 50 cm, and were allocated to 2,000 m 2 paddocks according to a randomised complete block design in a 2 × 2 factorial arrangement with four replications, from January 2001 to February 2002. Sward canopy changed from a vertical to a more horizontal orientation as the light interception area index and height increased from post to pre-grazing. Leaf canopy height pre-grazing was stable throughout the year and around 90 and 115 cm for the 95% and 100% LI treatments respectively, indicating a potential for development and use of target-based grazing management practices. Herbage mass pre and postgrazing was lower for the 95% than the 100% LI treatments, but with higher proportion of leaf and lower proportions of stem and dead material. Treatment effects on herbage accumulation were cumulative and became more evident as the experiment progressed, with up to 6 t ha -1 DM advantage to the 95/30 treatment. Although based on a single year experiment, grazing management should aim for low herbage mass during the transition period from winter to spring in order to allow fast recovery of swards and favour herbage accumulation during the following growing season. Key words: grazing management, leaf canopy height, leaf area index, light interception CARACTERÍSTICAS ESTRUTURAIS E ACÚMULO DE FORRAGEM EM PASTOS DE Panicum maximum cv. MOMBAÇA SUBMETIDOS A ESTRATÉGIAS DE PASTEJO ROTATIVORESUMO: Estratégias de pastejo promovem alterações na estrutura do dossel, afetando os padrões de acúmulo de forragem e flexibilidade ao manejo. O objetivo deste experimento foi avaliar as características estruturais do dossel e o acúmulo de forragem em pastos de capim-mombaça (Panicum maxium Jacq. cv. Mombaça) submetidos a estratégias de pastejo rotativo. Os tratamentos corresponderam a pastejos realizados quando os pastos atingiam 95 ou 100% de interceptação da luz incidente (IL) até alturas de resíduo de 30 e 50 cm, e foram alocados às unidades experimentais (piquetes de 2000 m 2 ) segundo um delineamento de blocos completos casualizados e arranjo fatorial 2 × 2, com quatro repetições, de janeiro de 2001 a fevereiro de 2002. O dossel passou de vertical para uma orientação mais horizontal à medida que o índice de área da folhagem e altura dos pastos aumentou durante a rebrota. A altura pré-pastejo do dossel mostrou-se estável durante o experimento e em torno de 90 e 115 cm para os tratamentos de 95 e 100% de IL, respectivamente, indicando potencial para o desenvolvimento e uso de práticas de manejo baseadas em metas de condição de pasto. A massa de forragem pré e pós-pastejo f...

The objectives of this controlled study were to compare the effects of 2 different formulations of recombinant bovine somatotropin (rbST) on milk yield, milk composition (fat and protein), milk somatic cell count, and body condition score (BCS) among dairy cattle in a large commercial herd. Regulatory approved 500-mg zinc sesame oil base rbST (ZSO-rbST; Elanco Animal Health, Greenfield, IN) and vitamin E lecithin base rbST (VEL-rbST; LG Life Sciences, Seoul, South Korea) formulations were administered per the manufacturers' recommendations every 14 d over 17 injection cycles starting at 57 to 70 d of lactation (90 cows per rbST group). Control cows (n = 60) received no rbST. Somatotropin-treated animals (VEL-rbST and ZSO-rbST combined) had increased average milk yield and protein percentage and lower average BCS compared with control cows. For primiparous cows, average milk yield was 37.75 kg/d with the ZSO-rbST treatment and 35.72 kg/d with the VEL-rbST treatment. For multiparous cows, average milk yield was 40.13 kg/d with the ZSO-rbST treatment and 38.81 kg/d with the VEL-rbST treatment. There were no differences in milk fat percentage between VEL-rbST and ZSO-rbST treatments, but milk protein content was greater with VEL-rbST treatment than with ZSO-rbST treatment. Nonetheless, cows treated with ZSO-rbST yielded more kilograms of fat and protein per day than cows treated with VEL-rbST. No significant differences in BCS were found between both rbST treatment groups. The differential increase in milk yield between cows treated with ZSO-rbST and VEL-rbST was driven by rbST response differences both within the 14-d cycle and throughout the 17 injection cycles. The cows treated with VEL-rbST demonstrated a more variable 14-d milk yield response curve, with more pronounced valleys between injections compared with the ZSO-rbST formulation. In addition, only the ZSO-rbST treatment was effective in modifying the lactation persistency compared with control cows. Compared with the VEL-rbST formulation, the ZSO-rbST formulation yielded more kilograms of milk, fat, and protein with less milk variation throughout the seventeen 14-d lactation cycles for both primiparous and multiparous cows.

This study aimed to evaluate the effects of increasing levels of chitosan (CHI) on sugarcane fermentation profile and losses, chemical composition, and in situ degradation. Treatments were: 0, 1, 2, 4, and 8 g of CHI/kg of dry matter (DM). Twenty experimental silos (PVC tubing with diameter 28 cm and height 25 cm) were used. Sand (2 kg) was placed at the bottom of each silo to evaluate effluent losses, and silos were weighed 60 d after ensiling to calculate gas losses. Samples were collected from the center of the silo mass to evaluate silage chemical composition, in situ degradation, fermentation profile, and mold and yeast count. Data were analyzed as a completely randomized design, and the treatment effect was decomposed using polynomial regression. Chitosan linearly increased acetic acid and NH3-N concentration, while yeast and mold count, and ethanol concentration decreased. Intermediary levels of CHI (from 4.47 to 6.34 g/kg DM) showed the lower values of effluent, gas, and total losses. There was a quadratic effect of CHI on the content of non-fiber carbohydrates, neutral and acid detergent, and in situ DM degradation. The lowest fiber content was observed with levels between 7.01 and 7.47 g/kg DM, whereas the highest non-fiber carbohydrate content and in situ DM degradation were found with 6.30 and 7.17 g/kg DM of CHI, respectively. Chitosan linearly increased acetic acid and NH3-N concentration, whereas it linearly reduced ethanol concentration and count of yeast and mold. Thus, intermediary levels of CHI, between 4.47 and 7.47 g/kg of DM, decrease fermentation losses and improve the nutritional value of sugarcane silage.

O objetivo deste trabalho foi testar duas formas de hidrólise do bagaço de cana (com [17kgf/cm²]e sem [4kgf/cm²] rápida descompressão pós-hidrólise) e dois níveis de concentrado (25 e 45% MS) no desempenho e na composição corporal de novilhas em crescimento sob regime confinado durante 112 dias. Vinte e quatro novilhas Nelore e 12 Canchim foram distribuídas em delineamento de blocos casualizados em arranjo fatorial 2x2. Os resultados demonstraram que a omissão da explosão pós-hidrólise e o uso de níveis mais elevados de concentrado aumentaram o ganho de peso e o consumo de alimentos. Os resultados para ganho de peso e consumo de matéria seca, respectivamente, para tratamento sem vs com descompressão e 45 vs 25% de concentrado, foram 0,76 vs 0,67 e 0,76 vs 0,66 kg/d e 6,7 vs 5,8 e 6,8 vs 5,7 kg/dia. Entretanto, não houve diferença entre os tratamentos para conversão alimentar. Não foram observadas diferenças entre os tratamentos quanto à composição corporal determinada por meio do espaço de deutério ao final do período de confinamento, embora a taxa estimada de deposição de lipídios tenha sido maior para o tratamento sem explosão (216 vs 175 g/d) e o tratamento com 45% de concentrado (225 vs 166 g/d). Não foram observadas vantagens na descompressão rápida pós-hidrólise em alta pressão na eficiência de conversão de alimentos. Os resultados demonstram que animais alimentados com bagaço hidrolisado em níveis altos de ingestão (2,9% PV) e proporções baixas de concentrado apresentaram eficiência de utilização da dieta semelhante a dietas com níveis mais altos de concentrado.

The objective of this study was to determine the effect of the dietary inclusion of lipid-based diets (whole cottonseed and protected fat) on the centesimal composition, fatty acid profile, and sensory properties of meat from finishing Nellore cattle. The study was carried out from August to October 2009. Thirty nine uncastrated Nellore males with average initial body weight of 494.1 ± 10.1 kg and 36 months of age were housed for 63 days in pens with thirteen animals each. A completely randomized design with three treatments and thirteen replications was used. The treatments evaluated were: feed with 2.50% cottonseed (control diet); feed with 11.50 % cottonseed; and feed with 3.13% cottonseed added of protected lipid (PL), all on a dry matter basis. No differences between treatments were observed for moisture, protein, and ash contents. However, the addition of protected fat caused an increase in the percentage of ether extract in the meat. Diets containing cottonseed or protected lipid did not affect fatty acid concentration in the meat. The intensity of the aroma, strange aroma, flavor, strange flavor, juiciness, color, and overall appearance were similar between treatments, except for tenderness, which was positively affected in cattle fed a diet in which the only lipid source was cottonseed. The study demonstrated that the addition of PL in the diets of finishing cattle led to greater levels of intramuscular fat, but to less tender meat than the other treatments.

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The current study aims to evaluate the effects of increasing levels of xylanase enzyme (XYL) on sugarcane silage fermentation, fermentative losses, chemical composition, dry matter (DM), neutral detergent fibre (NDF) degradation and aerobic stability. A completely randomized design trial was performed with five treatments and 50 experimental silos. Treatments were: 0, 100, 200, 300 and 400 mg of XYL per kg of DM. XYL contained 10 000 U/g. There was a quadratic effect of XYL on silage pH and acetic acid concentration: lower pH and higher acetic acid concentrations were found at intermediary levels of the enzyme. XYL decreased lactic acid concentration linearly. Furthermore, the enzyme had a quadratic effect on effluent and total losses, with higher losses at intermediary XYL levels. There was a quadratic effect of XYL on organic matter (OM), non-fibre carbohydrates (NFC) and crude protein (CP) content. In addition, a quadratic effect of XYL was observed on NDF content and degradation. Intermediary levels of XYL showed higher concentration of OM and NFC. The addition of XYL had no effect on silage temperature and pH after aerobic exposure. Thus, intermediate levels of XYL increased acetic acid and decreased silage pH. Besides positive effects on silage composition, intermediary XYL levels decreased NDF degradation.