Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 46 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Reproductive performance of female Nile tilapia (<strong> <em>Oreochromis niloticus</em></strong> ) fed diets with different digestible energy levels]]> ABSTRACT This study aimed to evaluate the reproductive performance of female Nile tilapia (Oreochromis niloticus) fed diets containing different levels of digestible energy (DE). The fish were housed in 15 fiberglass tanks (500 L) in a recirculating system at an average temperature of 27.5 °C. The treatments consisted of five diets with increasing levels of DE (3,200; 3,400; 3,600; 3,800; and 4,000 kcal/kg). The levels of DE did not significantly influence the final weight or the hepatosomatic, gonadosomatic, and visceral fat indices. The absolute fecundity was influenced by the treatments, for which the highest values were observed from the 3,600 kcal/kg DE level and upward. The proximate composition of the fish also had a significant effect on the variables crude protein, ether extract, and ash; the fish fed diets with higher levels of DE exhibited the lowest body protein content, while the accumulation of ether extract exhibited the opposite response. A level of 3,600 kcal/kg of digestible energy should be used in diets with 380 g/kg crude protein and a starch/lipid ratio of 1.33 for female Nile tilapia. <![CDATA[Agronomic evaluation of <strong><em>Paspalum notatum</em></strong> Flügge under the influence of photoperiod]]> ABSTRACT The objective of this study was to evaluate the influence of photoperiod on the forage yield by ecotypes and intraspecific hybrids of P. notatum. Tetraploid ecotypes from the United States Department of Agriculture and the National University of the Northeast in Argentina, in addition to six intraspecific hybrids, totaling 19 ecotypes, were assessed. The materials evaluated were subjected to an extended photoperiod (14 h of light) and natural photoperiod from July 2011 to October 2012. The experimental design was a completely randomized factorial scheme of 19 × 2 (ecotypes × photoperiod) consisting of five replicates. The materials were influenced differentially by the variation in photoperiod, with one group showing high sensitivity, whereas another, smaller group, was insensitive to this factor. The use of materials with differentiated responses to photoperiod in different climatic regions can be an important tool to increase forage yield of Paspalum notatum. <![CDATA[Use of <strong><em>Lippia rotundifolia</em></strong> and <strong><em>Cymbopogon flexuosus</em></strong> essential oils, individually or in combination, in broiler diets]]> ABSTRACT This study investigated the effects of Cymbopogon flexuosus and Lippia rotundifolia microencapsulated essential oils on broiler performance and carcass yield. One hundred and fifty mixed-sex Cobb broiler chicks were used, from one day up to 42 days of age, in a completely randomized design, with five treatments and three replicates of ten birds each. The treatments were: negative control (basal diet), positive control (diet with enramycin and salinomycin), and three diets with microencapsulated essential oils from lemongrass, L. rotundifolia, and combination with 50% of both. The performance and carcass yield were not affected by the treatments. The intestine absolute weight was lower in the combination treatment compared with the negative control treatment and the lemongrass essential oil. The intestine relative weight was higher in the treatments with lemongrass and L. rotundifolia essential oils in relation to the combination. The liver relative weight was lower with the lemongrass essential oil and the combination compared with the treatment with the L. rotundifolia essential oil. The trial could not find results enough to recommend the use of the lemongrass and L. rotundifolia essential oils as an additive in broiler diets. <![CDATA[Effects of different levels of expanded perlite on the performance and egg quality traits of laying hens]]> ABSTRACT The influence of different levels of expanded perlite on the performance and egg quality traits was studied in laying hens. Forty Lohmann Brown females at 30 weeks of age were randomly assigned to four groups consisting of five replicates with two hens in each. Four diet groups were supplemented with 0% (control group), 1%, 2%, and 3% perlite, respectively. Feed and water were provided ad libitum. There were no significant differences in final body weight, feed intake, egg yield, and egg weight. Feed conversion ratio and egg weight decreased with addition of 2% perlite. Dietary perlite supplementation has no significant effects on shape, yolk, and albumen index. Haugh unit was affected significantly by addition of 2% perlite. Fecal pH, dry matter, and NH3-N did not significantly differ among treatments. Dietary perlite has no negative effect on performance and egg quality traits except 2% perlite group. Dietary expanded perlite can be added at 1% level in laying hen rations without changing the animal performance. <![CDATA[Morphometric measurements and animal-performance indices in a study of racial forms of Brazilian Sport Horses undergoing training for eventing]]> ABSTRACT This study aimed to evaluate, in a practical manner, the use of linear and angular measurements and different animal-performance indices in a study on the breed-specific conformation of Brazilian Sport Horses training for eventing. These data can form the basis for the development of future studies based on the parameters evaluated and the calculations made. Seventeen Brazilian Sport Horses training for eventing were selected. Morphometric evaluations were made of all animals using linear and angular measurements. The linear measurements were withers, croup, and barrel heights; body, croup, shoulder, neck, and head lengths; head, chest, and hip widths; distance from the elbow to the ground and from the sternum to the ground (empty substernal); and thorax, forearm, knee, fetlock, and fore cannon girths. The angular measurements were shoulder-ground, shoulder-humerus, humerus-radius, metacarpus-phalanx, coxae-ground, coxae-femur, femur-tibia, and tibia-metatarsus angles. Thirteen animal-performance indices were calculated to have a better understanding of the conformation of the animals and their proportions: the relationship between the withers and croup heights, chest index, dactyl-thoracic index, estimated weight, body index, thoracic index, conformation index, load index 1, load index 2, relative body index, compactness index 1, compactness index 2, and meloscopic index. Brazilian Sport Horses in eventing training were within the expected conformation for an athletic horse, but the animal-performance indices differed among them because they are heterogeneous horses resulting from crossing among various different breeds. The use of linear and angular measurements allows the correct characterization of racial forms of Brazilian Sport Horses undergoing training for eventing. Animal-performance indices can be useful in a study of a breed-specific conformation of athletic horses. <![CDATA[Peripheral regulation of stress and fear responses in pigs from tail-biting pens]]> ABSTRACT This study focused on stress physiology by characterizing cortisol responses to stressors in tail biters (n = 10), victims (n = 10), and control pigs (n = 10) of two different breeds (Landrace × Yorkshire, LY; Landrace/Yorkshire × Landrace/Duroc; LYLD) and sexes (females and castrated males). We exposed pigs to 10 min of isolation with a human at the farm and transported them to a controlled environment. There, the behaviour was registered for 10 min during sessions when subjected to a novel object test and to a novel arena test. Sampling times of salivary cortisol were in all the fear tests before testing and 60 min thereafter, while for transportation as well 120 min after the beginning of transportation. We additionally measured cortisol at 7:00 and 16:00 h during three days following transportation. The basal stress axis activity followed a distinct diurnal rhythm between sexes and breeds, with castrated males having higher cortisol level than females and LY pigs higher than LYLD pigs. Following isolation at the farm and transportation, the concentration of salivary cortisol was higher in LY than in LYLD pigs. Pigs considered the exposure to a novel arena, but not to a novel object, stressful by showing a cortisol level after testing higher than before testing. The results suggest a genotypic effect on sensitivity to stress in pigs that have performed tail biting, have been victimized, or have not been involved in tail biting. <![CDATA[Use of dried brewers' grains instead of soybean meal to feed lactating cows]]> ABSTRACT The objective of this study was to determine the optimal level of dried brewers' grains (DBG) to replace soybean meal in diets for lactating Holstein cows. Five cows, around 88±28 days in milk, were distributed in a 5 × 5 Latin square design and fed diets containing different levels of DBG (0, 25, 50, 75, and 100%). The forage:concentrate ratio of the diet was 50:50. Feed intake, dry matter, nutrient digestibility, microbial synthesis, milk production and composition, and the economic viability of the diets were evaluated. There was reduction in dry matter intake and, consequently, in crude protein and non-fiber carbohydrates with increased levels of DBG. This occurred due to physical limitation of rumen caused by increased neutral detergent fiber intake. Ether extract intake also increased with levels of DBG due to higher concentrations of this nutrient in the diet. Apparent dry matter, organic matter, ether extract, and neutral detergent fiber digestibility increased with replacement of soybean meal by DBG. Milk production showed a quadratic effect and the levels of fat, protein, and total solids reduced linearly. Each 1% of soybean meal replaced by DBG in concentrate led to a reduction of 0.04, 0.02, and 0.06 g kg-1 of milk fat, protein, and total solids, respectively. The milk production efficiency increased linearly and the microbial synthesis efficiency was not affected. The economic return increased along with the DBG levels. Thus, DBG levels replacing up to 75% of soybean meal can be used to feed lactating cows, since it provides improvements in digestibility, milk production efficiency, and economic return without affecting microbial efficiency. <![CDATA[Phenotypic association between feed efficiency and feeding behavior, growth and carcass traits in Senepol cattle]]> ABSTRACT The objective of this study was to evaluate the associations between feed efficiency and feeding behavior, growth and carcass traits in Senepol cattle. A total of 137 animals were evaluated. Of these animals, 36 males were evaluated in a second test, totaling 173 records (initial age of 466±96 days and initial weight of 426±104 kg). Residual feed intake (RFI) was calculated as the difference between observed and expected dry matter intake, estimated by regression of dry matter intake on average daily gain and metabolic body weight (BW0.75), and the animals were classified as negative (high efficiency) and positive RFI (low efficiency). The mean RFI was -0.838±0.078 and 0.797±0.075 kg DM day-1 for negative and positive RFI animals, respectively, with a difference of 1.63 kg dry matter day-1. The dry matter intake of negative RFI animals, expressed as kg day-1 and percentage of mean body weight, was 11.3% and 13.1% lower than that of positive RFI animals. Negative RFI animals spent less time at the feed bunk and ingested less dry matter per visit than positive RFI animals, but did not differ in terms of chest girth, scrotal circumference, or hip height. However, negative RFI animals had lower rump fat deposition (7.13±0.477 mm) than positive RFI animals (7.83±0.473 mm). The Spearman correlation between RFI estimated in the first and second tests was 0.69, indicating that RFI is consistent when evaluated during two different periods of the life of the animal. Senepol animals with low residual feed intake (high efficiency) deposit less subcutaneous rump fat, but this reduction is not accompanied by a reduction in backfat thickness and longissimus muscle area. <![CDATA[Performance of lactating dairy cows fed sunflower or corn silages and concentrate based on citrus pulp or ground corn]]> ABSTRACT This study aimed to evaluate the effect of diets containing sunflower or corn silages and concentrate based on citrus pulp or ground corn on intake, apparent digestibility, feeding behavior, microbial protein production, and production, composition, and fatty acid profile of milk from dairy cows. Eight multiparous lactating Holstein cows (586±61 kg live weight; 25.0±4.0 kg daily milk yield at 80 to 120 days in milk) were randomly assigned to a double 4 × 4 Latin square design with a 2 × 2 factorial array. The experimental diets were: sunflower silage + citrus pulp-based concentrate; sunflower silage + ground corn-based concentrate; corn silage + citrus pulp-based concentrate; and corn silage + ground corn-based concentrate. The dry matter intake was highest for diets containing sunflower silage and lowest for diets with citrus pulp. Sunflower silage provided the highest intakes of crude protein, neutral detergent fiber, and ether extract. Except for the ether extract, the type of forage and carbohydrate did not influence the apparent nutrient digestibility. The forage and carbohydrate sources did not influence the feed eating time, but animals fed sunflower silage showed decreased rumination time and chewing activity. The microbial protein production was not altered with the diets. No differences were observed for milk production or composition, except for the milk urea nitrogen and lactose concentration. The type of forage influenced the milk fatty acid profile, to which corn silage presented higher values for fatty acids up to a 17-carbon chain length. The inclusion of sunflower silage and citrus pulp, compared with corn silage and ground corn, alters dry matter intake and ingestive behavior, but maintains milk production and composition with satisfactory characteristics of the milk fatty acid profile, providing an alternative feed for dairy cows. <![CDATA[A proposal for the evaluation of the bioeconomic efficiency of beef cattle production systems]]> ABSTRACT The objective of this study was to identify types of production system and their main indicators on bioeconomic efficiency, using qualitative and quantitative methods to evaluate beef cattle farms in the western region of the state of Rio Grande do Sul. A survey was carried out with 43 farmers operating in the western region of that state. All farms operated with complete cycle production systems in areas larger or equal to 900 ha. A qualitative questionnaire with binary answers and a quantitative questionnaire with numerical answers were applied. Technology and Management drivers were used for the calculation of the efficiency index of farmers obtained by both questionnaires. Farmers were divided into three clusters: low-efficiency level (LEL), intermediate-efficiency level (IEM), or high-efficiency level (HEL), as a result of the comparison of the scores obtained for the analyzed parameters. Subfactors resulting from each comparison (LEL × IEL; LEL × HEL, and IEL × HEL) were different as a function of the comparison and of the methods applied. Low-efficiency level farmers need to improve essential production processes, such as technology and management, as well as health management practices together with the financial management of the production system. Intermediate-efficiency level farmers need to improve their routine animal management, pasture management, and calculation of financial indicators to become highly efficient. The quantitative method allowed to identify underestimation (39.3%) or overestimation (24.2%) when farmers were are classified in clusters. Different methods may be used, but those based on quantitative information have stronger discrimination power to identify different types of farmers. <![CDATA[Nutritional and microbiological quality of bovine colostrum samples in Brazil]]> ABSTRACT The objective of this study was to evaluate the nutritional and microbiological composition of colostrum samples collected from colostrum banks or newly calved cows on dairy farms. For this purpose, 66 colostrum samples from dairy cows were directly collected during the milking of newly calved cows or from colostrum storage bank. Samples were collected from commercial properties in the states of Minas Gerais, São Paulo, and Paraná - Brazil, which were classified according to the total daily milk yield (MY). Even though average immunoglobulin concentrations were either adequate (79.7 and 51.7 mg/mL, for farms with MY&gt;701 L/d and &lt;200 L/d, respectively) or marginal (48.1 mg/mL for MY between 201-700 L/d), for only 48.4% of the colostrum samples, immunoglobulin concentrations were greater than 50 mg/mL. A variety of factors such as production system, animal breed, and time of sample collection can also affect the variables studied. In addition to emphasizing nutrition, good hygiene practices during the colostrum collection and storage process also deserve attention, since 24% of colostrum samples were below the microbial quality parameters. When nutritional and microbiological quality were simultaneously analyzed, only 22.6% of colostrum samples met the recommendations. Therefore, most of the calves in this region of Brazil are likely to present failure of passive immunity transfer and are exposed to pathogens when fed maternal colostrum. <![CDATA[Sugarcane bagasse as exclusive roughage for dairy heifers]]> ABSTRACT The objective of this study was to evaluate the effect of different concentrate levels (40, 50, 60, and 70% on dry matter basis) on intake, digestibility of nutrients, and performance of heifers fed sugarcane bagasse as exclusive roughage. Twenty Girolando heifers, with an average body weight of 198±25.6 kg were assigned to a completely randomized design, established according to body weight. The intake of dry matter (5.12 to 7.73 kg d-1), organic matter (4.72 to 7.32 kg d-1), crude protein (0.71 to 1.05 kg d-1), and digestible organic matter (3.09 to 4.77 kg d-1) linearly increased with the inclusion of concentrate in the diets. The final weight (238 to 299 kg d-1), body weight gain (0.50 to 1.20 kg d-1), and total weight gain (35.2 to 83.6 kg d-1) linearly increased with the concentrate levels. Considering the occurrence of the first calving at 24 months, a 50:50 ratio of sugarcane bagasse to concentrate seems to be the most appropriate for crossbred heifers.