Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 44 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Seasonal variation in sperm characteristics of boars in southern Uruguay]]> The objective of this study was to evaluate the effects of season, natural photoperiod, and room temperature at the housing facility on boar semen characteristics in Uruguay (34º66'S; 56º29'W). For this purpose, 117 ejaculates, obtained from eight adult males collected through 12 consecutive months, were assessed for sperm viability, DNA integrity, abnormalities (total, primary, and secondary), ejaculate volume, and sperm concentration. Viability, total and primary abnormalities, volume, and sperm concentration were affected by season. Sperm viability, volume, and sperm concentration were affected by natural photoperiod. In general, autumn and the decreasing photoperiod had a negative impact on most of the semen characteristics, except for volume. Housing temperature did not affect semen characteristics. In boars living in temperate climates, semen quality is negatively affected during autumn and is related to photoperiod changes; however, the effects of temperature changes in housingdo not affect these seminal characteristics. In this scenario, seasonal differences in semen quality may have a negative effect on sow fertilization. Consequently, semen quality control especially during autumn is imperative for the best boar selection to be used for insemination purposes. Seasonal differences in semen quality may have a negative effect on sow reproductive performance. This issue will be addressed in a future investigation. <![CDATA[Seasonal and circadian variation of the sexual behavior of Morada Nova rams in tropical environment]]> The objective of this study was to evaluate the seasonal and daily variation in sexual behavior of Morada Nova breeders raised in the Brazilian semi-arid region. The data were collected from four rams and 114 ewes of the Morada Nova breed - 55 females in the dry season and another 59 in the rainy season. Observations were performed in the dry and rainy seasons, divided into four times of the day: morning (05:01 h to 11.00 h), afternoon (11.01 h to 17.00 h), evening (17.01 h to 23:00 h), and dawn (23:01 h to 05.00 h). Sexual behavior was assessed for a period of 24 h/day, in a breeding season. One ram was used each three days. The behavioral patterns of the rams in view of females were observed during the recognition (sniffing the female urine, bouts of anogenital sniffing, and flehmen reaction), preparatory (exposure of tongue and penis, leg-kicking, and low-pitched bleats), and copulatory (number of mounts, number of ejaculations, and refractory period) phases. The rams were more active during daytime. The animals in the rainy season showed more efficient sexual behaviors by the lower frequency of mounts per ejaculation and greater number of ejaculations in a shorter time. In contrast, courting behaviors such as exposure of tongue, number of mounts, low-pitched bleats, and leg-kicking were more frequent in the dry season. In the semi-arid region with latitudes close to 7°N, Morada Nova rams have a higher intensity of precopulatory behaviors and lower frequency of ejaculations in the dry season. <![CDATA[Response of laying hens to methionine + cystine intake by dilution technique]]> The objective of this study was to measure the response of Dekalb White laying hens to different intakes of digestible methionine + cystine (met+cys) to optimise their performance. Two hundred eighty-eight Dekalb White laying hens, ranging in age from 33 to 48 weeks, were used in the study. The birds were randomly allocated into eight treatment (levels of met+cys and the control treatment) groups with six replicates of six hens per unit. The experimental diets consisted of seven increasing levels of met+cys (1.37, 2.75, 4.14, 5.51, 6.89, 7.92 and 8.95 g kg−1) and were prepared using a dilution technique. A control treatment was used to confirm that the limiting response was due to met+cys intake. Egg production, feed intake, egg weight, egg mass and feed conversion per mass were measured. The data were analysed with repeated measures and regression analyses using Broken Line and Quadratic models, as well as using the combination of both models. The different met+cys intakes influenced the studied variables; all the variables except feed conversion per mass were significantly different between the periods and levels. The digestible met+cys intakes based on the association of the Broken Line and Quadratic models to optimise the birds' response to egg mass are 671 mg/bird d for 33 to 36 weeks, 728 mg/bird d for 37 to 40 weeks, 743 mg/bird d for 41 to 44 weeks, and 770 mg/bird d for 45 to 48 weeks. <![CDATA[Effects of supplementation with Saccharomyces cerevisiae and aerobic training on physical performance of Mangalarga Marchador mares]]> The objective of this study was to assess the effects of supplementation with Saccharomyces cerevisiae on the performance of Mangalarga Marchador equines and to verify the effectiveness of the aerobic training protocol adopted. The study used 14 Mangalarga Marchador mares in a completely randomized split-plot design. The plots were made up of two treatments (groups Probiotic and Control) and the split plots comprised two maximal-effort physical tests applied both before and after the six weeks of training. The animals' spirometric parameters, heart rate, and plasma lactate levels were assessed. No difference was found between the Probiotic and Control groups in any of the parameters assessed. A difference was found in the physical tests for time-to-fatigue, aerobic and anaerobic thresholds, speed at which plasma lactate levels reached 2 and 4 mmol/L, speed at which the heart rate reached 200 bpm, and the lactate level at 30 min of the recovery period. Supplementation with Saccharomyces cerevisiae has no effect on physical conditioning of Mangalarga Marchador mares and the aerobic training protocol adopted increases the animals' aerobic and anaerobic capacity. <![CDATA[Productive performance and blood parameters of bulls fed diets containing babassu mesocarp bran and whole or ground corn]]> The objective of the present study was to evaluate the effects of corn milling and the inclusion of babassu mesocarp bran (BMB) on productive performance, digestibility of dietary nutrients, and blood parameters of dairy crossbred (Holstein-Gyr) bulls finished in confinement. Twenty-four bulls were fed four different experimental diets, containing two levels of inclusion of BMB (0 and 41.24%) and corn supplied in two different forms (ground and whole), for 98 days (77 days of data collection and 21 days of adaptation). The intakes and digestibility coefficients of the dry matter (DM) and nutrients were determined. There were no significant interaction effects of the BMB inclusion level and the form of corn used on the performance and digestibility variables. The intakes of DM, crude protein (CP), and neutral detergent fibre (NDF) increased with the inclusion of BMB in the diets. However, the inclusion of BMB in the diets decreased the ether extract intake, the NDF apparent digestibility, and the feed efficiency of DM and CP. Dry matter and NDF intakes also increased with the use of ground corn in the diet, which promoted an increase in the intake of total digestible nutrients (TDN), digestibility of non-fibrous carbohydrates, and average daily gain. However, the supply of ground corn reduced the feed efficiency of TDN. The remaining measured variables did not vary with the tested diets. The levels of plasma protein and albumin remained normal, but glucose concentrations were always high, irrespective of the tested diet. The form of corn supplied and the level of BMB inclusion had a significant interaction effect on the levels of triglycerides, urea, aspartate aminotransferase, and alkaline phosphatase. Babassu mesocarp bran can be included up to 41.24% in the diet of confined bulls without a negative effect on the animal weight gain. Corn should be supplied ground because this form improves the performance of crossbred bulls