Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 46 num. 2 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Effects of feeding strategy on larval development of the Amazon River prawn <strong><em>Macrobrachium amazonicum</em></strong>]]> ABSTRACT Effects of four feeding regimes on the development and feed intake, survival, productivity, and growth of Macrobrachium amazonicum larvae were investigated. Larvae were fed from stage II to IX, as follows: Artemia nauplii + inert diet during the entire larval cycle (AIn); Artemia nauplii for the entire larval cycle + inert diet from stage V onward (A/AIn); Artemia nauplii until stage IV + inert diet from stage IV onward (A/In); and only inert diet for the entire larval cycle (In). Each feeding regime (treatment) was carried out in three 50-L rectangular black tanks, set up in a recirculating system, filled with 10 salinity brackish water, and stocked at 81.8±0.8 larvae/L. The larval stage index, occurrence of Artemia nauplii and/or inert feed into the digestive tract, survival (number of larvae and postlarvae), productivity (number of postlarvae/L), and weight gain (mg) were evaluated. Larval development was similar in treatments AIn, A/Ain, and A/In, but was delayed in treatment In. Artemia nauplii were ingested by larvae irrespective of developmental stages, while inert feed was ingested only from stage III onward. Survival and productivity were higher in treatment AIn and decreased according to the number of days larvae were fed Artemia nauplii. Macrobrachium amazonicum larvae are omnivorous and polytrophic, but live feed is essential in the first stages and act as a complementary diet in the last half of larval cycle. There is a potential for inert diet to replace Artemia in the last phase of development if the nutrient composition matches larvae requirements. The combination of Artemia nauplii and inert diet during all larval cycles is the best management to maximize productivity. <![CDATA[Genetic associations between reproductive and linear-type traits of Holstein cows in Brazil]]> ABSTRACT This study aimed to estimate heritability, genetic, and residual correlations between reproductive traits such as age at first calving, calving interval, dry period, and first service period and linear type traits measured in Holstein cows born between the years 1990 and 2008 in Brazil. The (co)variance components were estimated by restricted maximum likelihood, using the MTDFREML software. The heritability for reproductive traits and linear-type traits ranged from 0.02 to 0.03 and from 0.07 to 0.40, respectively. Estimates of genetic correlations between reproductive and linear-type traits ranged from -0.23 (top line) to 0.28 (angularity) to age at first calving, from -0.54 (final score) to 0.34 (foot angle) to calving interval, from -0.23 (angularity) to 0.56 (stature) to dry period, and from -0.52 (final score) to 0.36 (height udder) to first service period. Direct selection for any of the reproductive traits implies low genetic gains by virtue of their low heritabilities. Among the linear-type traits, the final score, chest width, top line, angularity, teat length, udder attachment, rear teat placement were highlighted as good auxiliary traits to improve reproductive efficiency of Holstein cows in Brazil. The simultaneous selection for reproductive and linear-type traits can lead a higher genetic progress in the reproductive traits. <![CDATA[Mitochondrial and Y chromosome genetic diversity in the Portuguese Lidia bovine breed]]> ABSTRACT A total of 80 samples were collected to analyze the mitochondrial DNA (mtDNA) and Y chromosome genetic diversity of two main Portuguese Lidia bovine populations and clarify their genetic relationships with Spanish Lidia lineages. A 521-bp D-loop fragment was sequenced in 40 animals belonging to four herds (three Brava dos Açores and one Casta Portuguesa) and the same number of samples were collected with equal distribution from males in order to genotype six microsatellites, one single nucleotide polymorphism, and one indel. The mtDNA diversity recorded was similar to that observed in Lidia cattle. Haplotype T3 was the most common (62.5%), followed by the African T1 haplotype (25%); very low frequencies were recorded for haplotypes T2 (2.5%) and the Lidia haplogroup L4 (10%). The results support the existence of two major ancestral lines for the Lidia breed: European and African, similar to other Mediterranean breeds. However, the genetic diversity in the Y chromosome was lower in Portuguese Lidia lineages than in Lidia cattle and other bovine breeds (haplotype diversity = 0.09). The two major paternal haplogroups, Y1 and Y2, were present with 2.5% and 97.5%, respectively. Our results evidenced a similar paternal and maternal genetic pattern to those found in Spanish Lidia lineages and a high reproductive isolation. <![CDATA[Influence of eggshell colour on egg yolk antibody level, incubation results, and growth in broiler breeders]]> ABSTRACT This study was performed to determine the effect of shell colour in eggs acquired from Ross-308 broiler breeders on the interior and exterior quality of the egg, the antibody content of the egg yolk, and growth performance. The shell colours of a total of 1350 eggs were classified, using a colorimeter, into three groups: dark (E&lt;64), medium (E:64.00-67.00), and light (E&gt;67). The difference between groups with respect to egg weight, shape index, shell weight, and Haugh unit value was significant. Egg yolk antibody content (IgY) was 6.658 mg/mL in the dark colour group, 5.130 mg/mL in the medium colour group, and 5.242 mg/mL in the light colour group. Among incubation characteristics, the fertility rate as, in order, 94.66%, 92.14%, and 87.92% in dark, medium, and light shell colour eggs, and the hatchability was 87.00%, 84.28%, and 80.57%, in the same order. No significant difference was observed between groups with respect to hatchability of fertile eggs and embryonic mortality rates. No significant difference was observed between groups for live weight, feed intake, and feed conversion ratio either. The eggshell colour has an effect on yolk antibody content and on the hatchability, but it has no influence on hatchability of fertile eggs, Haugh unit and growth performance. <![CDATA[Effects of carob ( <strong><em>Ceratonia siliqua</em></strong> ) pod byproduct on quail performance, egg characteristics, fatty acids, and cholesterol levels]]> ABSTRACT This study was carried out to determine the effects of a carob (Ceratonia siliqua) byproduct (CB) supplement in diets for laying Japanese quail (Coturnix coturnix japonica) on performance and egg internal-external quality traits, fatty acid profile, and cholesterol content. A total of 225 female quail at 12 weeks of age were distributed into five treatment groups with three replications (15 birds in each replication). The following treatments were tested: 0% (control, no CB supplementation); 3% CB; 5% CB; 10% CB; and 15% CB in the diets. Feed and water were provided ad libitum to quail. The lighting program was 16 h light and 8 h dark. The experiment lasted 60 days. Treatments had no significant effects on final weight, feed intake, feed conversion ratio, egg production, and mortality. The external egg quality characteristics, shape index, shell weight, shell thickness, albumen index, yolk index, yolk weight, yolk fat, yolk color, yolk cholesterol, stearic acid, oleic acid, and heptadecanoic acid concentrations were not significantly influenced by CB supplementation to quail diets. Haugh unit, egg yolk total saturated fatty acids, total mono or polyunsaturated fatty acids, linoleic acid, gamma linolenic acid, palmitic, and palmitoleic acid contents were significantly influenced by the treatments. Carob byproduct can be used up to 15% in laying quail diets without any negative effects on performance, mortality, or internal egg quality traits. <![CDATA[Retinol and mineral status in grazing foals during the dry season]]> ABSTRACT The objective of this study was to examine serum retinol and some mineral (zinc, iron, calcium, phosphorus, magnesium, and copper) levels in seven Mangalarga Marchador colts aged 329.48 days, reared on pasture in the city of Montes Claros, MG, Brazil, during the dry season. Equines were evaluated for four periods of 45 days during the total study period of five months. The foals had access to Panicum maximum cv. Tanzania pasture, while water and mineral salt lick were provided ad libitum. Blood samples were taken to determine serum retinol and levels of minerals, along with pasture samples to quantify beta-carotene in the grass. The results indicated that retinol levels varied (2.87 to 1.97 µg/dL) and remained below the standard levels. The levels of zinc, iron, calcium, and phosphorus did not vary significantly with average values of 36.79 µg/dL, 77.32 µg/dL, 10.33 mg/dL, and 9.99 mg/dL, respectively. However, zinc and calcium remained below standard concentrations of 60-120 µg/dL and 10.8-13.5 mg/dL, respectively, since the beginning of the study. On the other hand, copper and magnesium levels decreased over time (97.76 to 77.56 mg/dL and 2.86 to 2.21 µg/dL, respectively), but showed normal levels for horses during the research. Beta-carotene in grass showed a downward trend over time from 38.53 to 0.09 mg/kg of dry matter. The results also indicated a significant relationship between serum retinol and serum copper levels. Vitamin A supplementation is necessary whenever foals are fed pastures during the dry season. <![CDATA[Effects of low-protein diets supplemented with antioxidants on histopathology of testis and testosterone and performance of male Japanese quail ( <strong><em>Coturnix coturnix japonica</em></strong> )]]> ABSTRACT The present study sought to examine the effects of low-protein diets supplemented with natural and synthetic antioxidants on reproductive traits and performance of male Japanese quail. A total of 144 one-day-old quail chicks were randomly assigned to receive four different treatments, including a control diet (a basal diet) without antioxidant supplementation, low-protein diet without antioxidant supplementation, low-protein diet supplemented with the E-selenium antioxidant (a combination of vitamin E and selenium), and low-protein diet supplemented with the antioxidant Loxidan (a combination of propyl galat, ethoxyquin, and citric acid). Throughout the study, feed and water were provided ad libitum from one to 45 days of age. Performance values were calculated at the end of the experimental period. Blood samples were collected from the wing vein of six male birds randomly selected from each treatment group. Subsequently, blood samples were used to measure serum testosterone levels by ELISA. A total of 36 slides were prepared from testes of 12 adult quail for histological studies. Results from this study showed that there was a significant increase in blood testosterone levels of quail fed the antioxidant Loxidan. An increased number of spermatogonia was found in quail fed both antioxidants. In addition, a significant increase was found in the number of spermatid cells in quail fed a low-protein diet with antioxidants. Surprisingly, spermatozoa cells showed a significant elevation in quail fed antioxidants as compared with those fed low-protein diets. Interestingly, a significant increase was observed in the final body weight of the quail fed antioxidants. Therefore, it can be deduced that antioxidant intake not only can improve reproductive indices, such as testosterone levels and testicular tissue in Japanese quail, but is also useful for performance of quail fed low-protein diets. <![CDATA[Influence of dietary artemisinin supplementation on productive performance and haematological parameters of broiler chickens]]> ABSTRACT In the present study, we aimed to assess the toxicity of artemisinin on the haematological system and its effect on the productive performance of broiler chickens. Eighteen-day-old chickens were randomly divided into four groups of 30 chickens (three replicates of 10 broilers/group): control group and three experimental groups: ART5 - diet with 5 ppm of artemisinin; ART50 - diet with 50 ppm of artemisinin; and ART500 - diet with 500 ppm of artemisinin. Artemisinin enhanced the productive performances of broiler chickens at the lowest concentration (5 ppm), but at the highest concentration (500 ppm), it negatively affected weight gain and the feed conversion ratio. The performance characteristics of the chickens whose diets were supplemented with 50 ppm artemisinin were similar to those of the control group. Additionally, 5 ppm artemisinin in feed did not significantly affect the haematological parameters of the chickens, but 50 and 500 ppm artemisinin induced a gradual decline of the total leukocytes, lymphopenia, monocytosis, and eosinopenia, and the highest concentration caused anaemia. Artemisinin at a low concentration could be used as a feed additive in the poultry industry to improve organic broiler production performance with no serious side effects. <![CDATA[Carcass characteristics and meat evaluation of Nelore cattle subjected to different antioxidant treatments]]> ABSTRACT Forty Nelore cattle were used to evaluate the effects of supplementation with different antioxidants on carcass characteristics and meat quality of feedlot cattle. Animals were fed Brachiaria brizantha hay and subjected to five treatments (control and four antioxidants: zinc, selenium, vitamin E, and selenium + vitamin E). After a 105-day feeding period, cattle were slaughtered. Tissue composition, as well as carcass proximate composition, color, tenderness, pH, and fatty acid profile were evaluated. Analysis of variance was carried out and means compared by Tukey test at 0.05 probability. The group fed selenium showed the lowest muscle amount (66.61 g/100 g) compared with the other antioxidants evaluated. There was no difference among treatments for bone, fat, and comestible portion percentages as well as muscle:bone, muscle:fat, and comestible portion:bone ratios, with mean values of 16.85 g/100 g, 14.70 g/100 g, 82.99 g/100 g, 4.06, 4.85, and 4.95, respectively. Neither brightness, red, or yellow contents of the meat nor carcass pH were affected by treatments. For tenderness and losses during thawing and cooking, there were no differences among treatments, with averages of 6.43 kgf cm2, 3.22 g/100 g, and 21.15 g/100 g, respectively. Supplementation of Nelore cattle fed Brachiaria brizantha hay with antioxidants do not influence carcass characteristics or meat quality. However, vitamin E supplementation reduces the levels of omega 3 fatty acid, whereas supplementation with selenium + vitamin E promotes an increase in linoleic and palmitoleic acids and a decrease in myristoleic acid, making the supplementation feasible due to the beneficial effects provided by these acids. <![CDATA[The effect of organic selenium in feeding of ewes in late pregnancy on selenium transfer to progeny]]> ABSTRACT The objective of this study was to determine the effect of supplemented organic selenium at different levels to concentrate feed of Norduz ewes in late pregnancy on maternal serum, placenta, colostrum, and offspring serum concentrations. This study was conducted using two-year-old 35 Norduz ewes. Ewes were randomly assigned to one of three dietary treatments for 57 days prepartum and at the seven days postpartum. Group 1 was fed a standard pregnant sheep concentrate basal diet without any additional Se supplement (control). Experiment groups were fed diets supplemented with 0.150 mg/kg, 0.300 mg/kg, and 0.450 mg/kg organic selenium to the same basal diet. Results showed that addition of selenium to gestating ewe diets increased Se in serum after one week of feeding. Ewes supplemented with 0.300 and 0.450 mg/kg Se had increased placenta, serum, and colostrum Se levels compared with those fed the control diet (P&lt;0.05). There was a strong positive correlation between placental and serum Se concentration in ewes. Colostrum Se increased linearly with dietary Se in the treatment groups. At birth, lamb serum Se ranged from 48.96 ng/mL to 195.52 ng/mL and was affected by the Se concentration of the ewe diets, which indicated placenta transfer of selenium from the dam. As selenium level increased in basal diet, an upward trend was observed in maternal free thyroxine concentration. Likewise, serum free triiodothyronine, free thyroxine, and immunoglobulin G concentrations of lambs from the three treatment groups were significantly greater than of the control lambs. As a result, selenium supplementation was important for maintaining Se and immunoglobulin G concentration in placenta, serum, and colostrum in ewes. <![CDATA[Development and evaluation of models to estimate body chemical composition of young Nellore bulls]]> ABSTRACT The objective of this study was to develop accurate regression equations to predict body composition of Nellore cattle using chemical composition of the 9th, 10th, and 11th ribs and to evaluate the models proposed by analyzing mean and linear bias. Sixty-seven Nellore bulls were slaughtered and slaughter body weight (SBW), hot carcass weight (HCW), and 9th-, 10th-, and 11th-rib-cut weight (RCW) were measured. Empty body composition was obtained after grinding, homogenizing, sampling, chemical analysis, and pooling (blood, skin, head + feet, viscera, and carcass). Chemical components were determined in rib cut, carcass, and empty body: protein (RCP, HCP, and EBP), fat (RCF, HCF, and EBF), ash (RCA, HCA, and EBA), and water (RCWt, HCWt, and EBWt). Stepwise options were used to determine variables to be included and excluded from regressions. Predictive ability of equations was verified using standard error of prediction, coefficient of determination, and Cp statistic. Regression estimates were tested to evaluate the models in a database different from that used for equation development. The best equations found to predict carcass components, in kg, were: HCF = -0.994 + 0.123 × SBW - 9.201 × RCW + 34.249 × RCF (R² = 0.86) and HCWt = 2.733 - 0.172 × SBW + 0.821 × HCW - 23.939 × RCF + 12.186 × RCWt (R² = 0.96). For empty body, the best equations, in kg, were: EBF = -1.4 + 0.166 × SBW - 10.073 × RCW + 40.202 × RCF (R² = 0.90) and EBWt = 3.524 + 0.272 × SBW + 0.373 × HCW - 11.727 × RCW + 31.079 × RCWt (R² = 0.98). Body weight has a high predictive power and should be included in equations to estimate body composition of Nellore cattle. Unbiased models are valid as an indirect method for determining body composition in beef cattle. <![CDATA[Effect of soybean hulls on lactation curves and the composition of goat milk]]> ABSTRACT This study aimed to evaluate the effects of soybean hulls (SBH) as a ground corn replacement (0, 50, and 100% SBH) on the parameters of the lactation curve and on lactation curves and milk composition. Fourteen multiparous Saanen goats were used during their lactation period, from kidding until the drying of their milk on the 228th day of lactation, and were distributed in a completely randomised design. The data was analysed using Bayesian methodology to minimise the effect of the low number of animals and to allow for comparison of the curve parameters estimated by Wood's nonlinear model. The SBH had no effect on the initial milk yield; nevertheless, the SBH reduced the rate of yield until lactation peak and accelerated the declining rate of yield after lactation. The treatments did not affect dry matter intake. The inclusion of SBH increased the fat content in the milk, which was also influenced by the lactation stage of the goats. Effects were observed on polyunsaturated fatty acids (PUFA), PUFA/total AG ratio, and the n-6:n-3 ratio of goat milk fat. The lactation stage changed the content of saturated fatty acid, monounsaturated fatty acid, and C18:2 (conjugated linoleic acid). The SBH can therefore be used as a ground corn replacement in the diets of lactating goats, as changes in the lactation curve parameters did not result in changes in total yields. Nevertheless, if the milk fat increases, then as quality rises, so could payment by quality, and thus an increase in profit margins per liter of milk sold.