Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 43 num. 10 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Effect of seminal plasma and egg yolk concentration on freezability of goat semen]]> The objective of this study was to evaluate the effects of egg yolk and seminal plasma on the viability of cryopreserved goat semen. To this end, four fertile Saanen bucks, aged between 10 months and 1 year, and weighing 18 to 25 kg, were used. Semen was collected from each buck by the artificial vagina method at the end of breeding season (June-July). The extender used was the yolk citrate, which was split into two equal aliquots: 5% egg yolk (2.5 mL egg yolk: 47.5 mL citrate solution) were added to one of the samples and 10% egg yolk (5.0 mL egg yolk: 45.0 mL citrate solution) were added to another. The sperm motility and vigor after thawing and post thermal resistance test (TRT) were evaluated and the data were subjected to analysis of variance and means were compared by the F test at 5.0% probability. The observed values for motility and vigor after thawing and post thermal resistance test (TRT), fast and slow, according to the presence of seminal plasma and egg yolk percentage were: 5% egg yolk with plasma (25.0% and 3.3; 1.60% and 0.7; 12.36% and 1.6, respectively); 5% egg yolk without plasma (23.61% and 3.1; 1.25% and 0.2; 9.93% and 1.3, respectively); 10% egg yolk with plasma (30.8% and 3.3; 4.4% and 1.9; 19.5% and 2.7, respectively); and 10% egg yolk without plasma (13.4% and 2.5; 4.1% and 0.5; 17.0% and 1.0, respectively). There were significant differences between the analyzed data in relation to semen with or without plasma at different percentages of egg yolk, and the group that presented the best results was 10% egg yolk citrate in extender with plasma. The presence of seminal plasma and higher concentration of egg yolk in extender provide a higher viability of cryopreserved goat semen. <![CDATA[Rumen degradation and passage kinetics of silage made from different corn hybrids]]> The objective of the present study was to evaluate the parameters related to the digestion of the fiber from silages of four corn hybrids (BX1280, SHS4070, 2B433, and DKB390) developed for silage production. Four rumen-cannulated castrated Holstein × Zebu crossbred cattle with approximate initial weight of 400 kg were distributed in a Latin square design. To determine the fiber passage rate and degradability, the techniques of chromium-mordant and in situ incubation of the neutral detergent fiber of the silages in nylon bags were used. The profiles of concentration of the marker in the feces were described by the generalized two-compartment model. Corn hybrid DKB390 is the most indicated for production of better-quality silages, because its fiber is more degradable in the rumen as compared with the other hybrids tested. <![CDATA[Factors affecting feed efficiency in dairy goats]]> The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearson's correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency. <![CDATA[Forage cactus associated with different fiber sources for lactating Sindhi cows: intake, digestibility and microbial protein production]]> This experiment was carried to evaluate the effect of forage cactus with different fiber sources (elephant grass hay [EGH], corn straw [CS], hay of cassava shoots [HCS], fresh sugarcane bagasse [FSB], and hydrolyzed sugarcane bagasse [HSB]) on intake, apparent digestibility and macrobiotic protein production of cows. Five cows with 265 kg average body weight, 4.95 kg average daily milk yield and 5.22 kg 4% fat-corrected milk yield were randomly allocated to a 5 × 5 Latin square design. The animals fed cactus associated with CS, EGH and HCS showed higher intake of DM and nutrients. However, regarding the digestibility, diets with sugarcane bagasse showed higher digestibility compared with those with CS and hay. For microbial protein, the excretion of purine derivatives, synthesis of microbial N and microbial protein production were higher in the treatment with CS than in the treatment with sugarcane bagasse. On the other hand, the treatment with EGH and HCS did not have statistical differences compared with the other cases. The mean efficiency of microbial protein synthesis of the experiment was 131 g microbial crude protein/kg of TDN. The treatment with CS showed better efficiency; however, it was statistically superior only compared with FSB. The other treatments did not show statistical difference compared with the other cases. Diets with cactus associated with corn straw, hay of elephant grass or hay of cassava shoots provide higher intake of dry matter and nutrients and better metabolic response compared with diets with cactus associated with sugarcane bagasse for lactating Sindhi cows. <![CDATA[Sulfur sources in protein supplements for ruminants]]> The present study evaluates the efficiency of different sulfur sources for ruminant nutrition. The fiber digestibility and the amino acid profile were analyzed in the duodenal digesta of crossbred steers fed Brachiaria dictyoneura hay. The sources utilized were elemental sulfur (ES70S), elemental sulfur (ES98S); calcium sulfate in hydrated (HCS), CaSO4.2H2O, and anhydrous (ACS), CaSO4, forms; and ammonium sulfate (AS), (NH4)2SO4, keeping a nitrogen:sulfur ratio of 11:1. The iso-protein supplements had 50% of protein in the total dry matter (DM). Five Holstein × Zebu steers, which were fistulated in the rumen and abomasum, were distributed in a 5 × 5 Latin square. The different sulfur sources in the supplement did not affect any of the evaluated nutritional factors, such as intake of hay dry matter and protein supplement, crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), organic matter (OM), non-fibrous carbohydrate (NFC), ether extract (EE), total digestible nutrients (TDN), NDFap and CP digestibility coefficients, ruminal pH, and ruminal ammonia concentration. The concentrations of amino acids available in the abomasal digesta did not differ significantly in the tested diets. The sulfur sources evaluated in the present study are suitable as supplement for cattle, and their employment may be important to avoid environmental contaminations. <![CDATA[Concentrate supplementation during pregnancy and lactation of ewes affects the growth rate of lambs from a variety of crosses]]> The objective of this study was to determine how concentrate supplementation during late third gestation and lactation affects ewe and offspring performance from birth to weaning. Thirty-six ewes and their offspring (n = 32) were used. Eighteen Morada Nova and 18 Santa Inês ewes were artificially inseminated with semen from Dorper ram and distributed in a completely randomized factorial arrangement (2 × 2) consisting of two supplementation levels (5 and 15 g kg-1 of BW) and two breeds (Morada Nova and Santa Inês) or two crosses (Dorper × Morada Nova and Dorper × Santa Inês). The ewes were weighed, their body condition was evaluated during pregnancy, and the weaning weight of the lambs at up to 70 days old was measured. There was no effect of breed or supplementation on the prolificacy or type of birth. The Santa Inês ewes had a faster rate of development, although the weight loss during lactation was lower in the Morada Nova ewes. The weight development of the Dorper × Santa Inês lambs during the maternal-dependent phase was 34 g/100 g higher than that of the other cross, with no difference in the maternal-independent phase. Dorper × Santa Inês lambs gain more weight during the 70 days of development. However, the Dorper × Morada Nova lambs show a better response in terms of production efficiency when comparing the weight of the lambs with the weight of the sheep. <![CDATA[Live weight and metabolic hormone profile in steers moved in drives]]> The objective was to determine the effects of driving on the growth of steers during 55 days of moving by drive and 84 days after the arrival. Twenty-five steers were randomly chosen from a herd of 1,000 Nellore cattle, which were evaluated in two periods: the driving period, in which animals were moved a distance of 700 km on foot for 55 d; and the post-driving period, which lasted 84 d. Serum samples were obtained for hormone dosing (T3, T4, cortisol, and IGF-I) by radioimmunoassay using commercial kits. The data was collected at different time points during the experiment. No changes in live weight were observed between days 0 and 55. During the post-driving period, on the 28th, 56th, and 84th d, the average weights were 226.10 kg, 224.28 kg, and 242.6 kg, respectively; differences in weight were observed on the 84th d when compared with the 56th d. There were no changes in insulin and T3 levels in either periods; the lowest T4 concentration was observed during the driving period. The serum T4 concentration increased after 56 d of post-driving, and it was greater than the concentrations detected on the other days. The highest levels of cortisol were identified after 28 d of post-driving. An increase in IGF-I concentration was observed after 56 and 84 d of post-driving. Moving cattle by driving does not alter the weight of the animals and weight gain occurs during the post-driving period due to an increase in the T4 and IGF-I levels. <![CDATA[Effects of heat stress on the physiological parameters and productivity of hair sheep in tropical and coastal environments]]> The experiment was carried out with sheep during the finishing phase in a partial confinement system to evaluate the following physiological parameters: rectal temperature (RT), respiratory rate (RR), heart rate (HR), productive performance and carcass characteristics. Fourteen uncastrated sheep with an average initial age of 90 days belonging to two genetic groups were used. There were seven Santa Inês animals, whose average initial live weight (ILW) was 23.65 kg, and seven F1 Dorper × St. Inês animals, with an ILW of 20.02 kg. The treatments were the two genetic groups and two times for the collection of the physiological parameters, at 09.00 h and 15.00 h. Evaluation took place once a week, in a shared stall, always following a 20-min grazing activity. The animals had daily access to a Megathyrsus maximus (Jacquin) pasture, cultivar Masai, from 08.00 h to 17.00 h and their feed was placed in a trough, at a forage:concentrate ratio of 51:49 in the total dry matter. The concentrate consisted of 900 g/kg of ground corn and 100 g/kg of soybean meal, and the roughage supplied was alfalfa hay. There was no interaction between treatments for the studied variables. The physiological parameters were affected only by the time of day. The variables RR and RT were higher at 15.00 h, while the highest HR values were observed at 09.00 h. Neither of the two genetic groups differed for performance and carcass characteristics. Hair sheep belonging to close genetic groups show no differences in performance, carcass characteristics and physiological responses when subjected to heat stress.