Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 44 num. 11 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Genotypic stabilization of agronomic traits in Panicum maximum (Jacq.) hybrids]]> The objective of this study was to evaluate the genotypic stability of agronomic traits in hybrids of Panicum maximum. Hybrids originating from the crosses between two sexual parents and cultivars Mombasa and Tanzania were evaluated in an incomplete-block design. Evaluated traits were total dry matter, leaf dry matter, stem dry matter, percentage of leaves, and leaf:stem ratio. These traits were evaluated in six harvests. Overall, higher repeatability was observed for the traits total dry matter and leaf dry matter, especially when harvests 4, 5, and 6, occurring in spring and summer, were evaluated. The leaf dry matter was the trait that provided the greatest repeatability and determination. The repeatability of stem dry matter, percentage of leaves, and leaf:stem ratio had a low magnitude, even when the coefficient was estimated based on the harvests of better stabilization for the other variables. The hybrids achieved genotypic stabilization in the harvests made in the second rainy season. Harvests made in the rainy season provide greater repeatability and determination, and the inclusion of the dry-season harvest is detrimental to the process of selection of low-repeatability traits such as percentage of leaves. <![CDATA[Production and chemical composition of three sugarcane cultivars grown under Af climate conditions]]> The objective of this study was to evaluate the chemical composition and yield of three sugarcane cultivars grown under Af climate conditions. Three sugarcane cultivars were examined, namely, IACSP93-6006, RB83-5486, and SP79-1011, in a randomized block design with three treatments, four blocks, and two replicates per block; means were compared using Tukey's test at 5% probability level. Significant differences were observed for dry matter, ether extract, crude protein, acid detergent fiber, lignin (LIG), cellulose, neutral detergent fiber corrected for ash and protein (NDFap), total carbohydrates, carbohydrate fractions B2 and C, and dry matter yield. The fiber components (NDFap, LIG, and fraction C) displayed low values. The cultivars produced high dry matter yields, especially IACSP93-6006 and SP79-1011. There were no differences among sucrose (Pol) values and the NDF/Pol ratios. The low Pol values indicate that sugarcane grown under Af climate conditions does not produce high levels of sucrose. The three sugarcane cultivars grown under the Af climate conditions produce high yields of DM/ha but low concentrations of the fiber components, as well as low Pol concentrations. <![CDATA[Comparison of fattening performance, carcass characteristics, and egg quality characteristics of Japanese quails with different feather colors]]> The objective of this study was to compare fattening performance, carcass traits, and egg quality of Japanese quails with different feather colors (white, dark brown, golden, and wild-type). In the study, 360 one-day-old quail chicks with 4 different feather colors were used as animal material. Quails were fed ad libitum for 42 days to determine fattening performance and carcass traits. To determine egg traits, 48 hens from each group, in a total of 192, were selected and caged according to feather color. Eggs were collected for four consecutive weeks and egg quality characteristics were measured. Different feather colors had a significant effect on live weight, feed intake, feed conversion ratio, and carcass characteristics. Significant differences between the groups were detected for egg weight, specific gravity, shape index, shell weight, albumen weight, yolk weight, albumen index, and yolk index. Japanese quails with all four feather colors can be reared depending on the choice. However, due to lower feed conversion ratio, white-feathered quails may be preferred for meat production purposes. Color variations should be considered when selecting quails. <![CDATA[Protein requirements for growth in male and female Saanen goats]]> The objective of this study was to determine the protein requirements for the growth of intact male, female, and castrated male Saanen goats weighing 30 to 45 kg of body weight (BW) and to compare estimates of the protein requirements for maintenance (NPm) by the comparative slaughter and nitrogen balance techniques. To determine the maintenance requirements, 55 goats were assigned in a split-plot design using a 3 × 3 factorial arrangement (three sexes and three dry matter intake (DMI) levels). A linear regression of retained N (as measured by the slaughter technique and estimated from the nitrogen balance) on N intake on a daily basis was used to calculate the net protein for maintenance. The net protein requirement for weight gain (NPg) was obtained using 65 goats fed ad libitum in a completely randomized design. The first derivative of the allometric equation of protein content in the empty BW with respect to the empty BW yielded estimates of the NPg. According to the comparative slaughter technique, the estimated NPm was 1.46 g/kg of metabolic weight, which is 50% lower than the estimate from the nitrogen balance technique. When evaluating the variance of the error, the nitrogen balance also showed greater values, indicating less precision compared with that of the comparative slaughter technique. The daily NPg ranged from 155.7±10.9 to 153.4±13.5 g/kg of EBW gain for growing Saanen goats. The protein requirements (NPm and NPg) of intact male, female, and castrated male Saanen goats are similar, from 30 to 45 kg BW, in accordance with current feeding systems. Moreover, the results of the present study indicate that the estimate of NPm using the comparative slaughter technique is more precise and lower than that using the N balance technique. <![CDATA[Characteristics of the wool produced by ewes raised for meat production]]> The objective of this study was to evaluate the characteristics of wool produced by ewes of different genetic groups, ages, and reproductive statuses. A total of 115 ewes, of the following genetic groups, were used: 10 Corriedale, 37 Hampshire Down, 26 1/2 Hampshire Down + 1/2 Corriedale, 24 1/2 Ile de France + 1/2 Corriedale, and 18 1/2 Suffolk + 1/2 Corriedale. Age was determined by the number of permanent incisors, ranging from four teeth to eight teeth. Ewes were further classified by their reproductive status into: lambed, having reared one lamb; and not-lambed. Hampshire and half-blood Suffolk ewes were heavier (53.2 and 52.7 kg, respectively), while Corriedale animals were lighter (40.1 kg). Older ewes and not-lambed ewes were heavier as well. Fleece weight was higher for the Corriedale and its crossbred ewes (average of 2.9 kg). Genetic group did not affect yield after scouring (61.6%). Ewe age, reproductive status, and year of evaluation did not affect greasy fleece weight or yield. Fiber diameter and number of crimps were not affected by any tested variables, with mean values of 29.8 μm and 5.8 crimps per centimeter, respectively. Staple length was influenced only by genetic group, in which the Hampshire ewes showed the shortest staple (6.2 cm). In general, the character was classified as good to regular, and the worst was found in the Hampshire. That genetic group grew rough wool, while the others were rated as slightly soft to rough. All genetic groups presented wools with some medullation. The majority of the samples were classified from "Cruza 1" to "Cruza 3" in all five groups and, for quality, the majority of the samples were rated as Good. Wool produced by meat breeds presents variations of quantity and quality that should be considered by producers and industry.