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Monitoring weight development is essential for decision-making and assessing the effectiveness of management strategies. However, this practice is often hindered by the lack of scales on farms. This study aimed to characterize the weight development and growth curves of male and female Santa Inês lambs from birth to weaning, managed on pasture with creep-fed concentrate supplementation. Data from 212 lambs during the pre-weaning phase were analyzed. The animals were weighed every seven days to evaluate total weight gain and average daily gain. Biometric measurements were taken every 28 days. Mixed models were used to assess the effects of sex and birth type on birth and weaning weights. Simple and multiple linear regression models were employed to estimate live weight using biometric measurements. The non-linear Gompertz model was utilized to describe weight development and formulate growth curves. Results were considered significant at p < 0.05. An interaction effect between birth type and sex (p < 0.05) was noted for birth weight, with the lowest weight observed in twin-birth females (2.96 kg) and the highest in single-birth males (3.73 kg) and females (3.65 kg) (p > 0.05). Birth type significantly influenced average daily gain, total weight gain, and weaning weight (p < 0.05). The Gompertz model accurately depicted the growth curves, effectively describing the weight development. Pearson’s correlation coefficients between biometric measurements and weight were positive and significant (p < 0.05), ranging from 0.599 for hip height to 0.847 for heart girth. Consequently, the simple and multiple regression equations demonstrated high precision in predicting weaning weight. In conclusion, twin-birth lambs receiving concentrate supplementation via creep-feeding and managed on pasture showed different developmental patterns compared to single-birth lambs under the same conditions. The Gompertz model proved effective for monitoring development during the pre-weaning phase. All simple and multiple linear regression models were effective in predicting weaning weight through biometric measurements. However, for practical application, the model incorporating two measurements—body length and abdominal circumference—is recommended.

This study aimed to assess nutrient intake, performance, intake behavior, carcass characteristics, and meat quality of sheep managed on Masai grass pastures along with intermittent concentrate supplementation, in addition to the economic impacts of applying that strategy. A sample of 24 Santa Inês sheep (12 males and 12 females) was kept for 80 days on Panicum maximum cv. Massai pastures and was supplemented daily or every other day. The voluntary intake of dry matter and nutrients was estimated. Mean daily weight gain and total weight gain were calculated and intake behavior parameters were assessed. The males were slaughtered and the weight and yield of the carcasses and meat cuts were assessed. The meat was analyzed for cooking losses, shear force, and color. The gross margin of the system was estimated from the difference between total income and operational cost. No effect was seen of the interaction between supplementation frequency and sex for any parameter assessed (p > 0.05). Intermittent supplementation of Santa Inês sheep managed with Masai grass is recommended since the strategy does not impact nutrient intake, performance, intake behavior, carcass characteristics, or meat quality, but lowers the costs of producing 1 kg of meat by 15%.

The aim of this study was to evaluate the use of different mathematical models to describe the growth of lambs during the pre-weaning phase and the effect of sex on their growth curve. Data from 51 lambs (26 males and 25 females) with a genetic constitution of at least 50% Santa Inês breed were used. Lamb weight was monitored during the entire pre-weaning phase (91 days) by weighing the animals weekly on a scale suitable for sheep, to draw the body-weight growth curve. The adequacy of the models was evaluated by the coefficient of determination, simultaneous F-test for parameter identity, concordance correlation coefficient, root mean square error of prediction and decomposition of the mean square error of prediction. Pairwise mean square error of prediction analysis and delta Akaike information criterion were used to compare the models in terms of accuracy and precision. The evaluation of the adequacy of the tested models showed that the data predicted by the linear, quadratic and exponential models were similar (P > 0.05) to the observed data. In contrast, the monomolecular model generated predictions that could not be accepted as true. The linear and quadratic models showed better accuracy and precision. The first-degree linear model should be preferred over the other studied models to describe growth of sheep in the pre-weaning phase. Males and females exhibited distinct growth patterns.

Background. Beef cattle breeds need to be evaluated in pasture production systems. Objective. This study aimed to evaluate the performance, morphology and carcass characteristics of Sindhi bulls on pasture. Methodology. Twenty Sindhi bulls belonging to eight different herds of the state of Rio Grande do Norte were evaluated on an official weight gain test conducted by the Brazilian Association of Zebu Breeders (ABCZ). The experiment lasted for 294 days, including an adaptation period of 70 days. The animals were managed under a rotational grazing system, with periods of occupation of 20 days. Records of body weight and scrotal circumference measurements were taken every 56 days. Carcass evaluation and visual assessment were performed at the last weighing. Data were analyzed using descriptive analysis, simple linear correlation and means test. Results. The final body weight, average daily gain and scrotal circumference gain reached 304.60 kg, 0.482 kg/day and 10.29 cm, respectively. The loin eye area and intramuscular fat averaged 52.36 cm² and 1.25%, respectively. Significant and positive correlations between carcass ultrasound parameters were observed. Moreover, a positive and significant correlation between loin eye area and visual assessment was reported. There was no effect (P>0.05) of initial body weight on carcass characteristics, performance and visual assessment. Implications. Sindhi breed cattle are efficient in producing meat when fed exclusively with pasture, but need more genetic work that focuses on the deposition of adipose tissue in more valued regions of the carcass. Conclusions. The pasture-based gain performance test demonstrates the hardiness of the Sindhi breed, and the carcass evaluation validates the breed's aptitude for meat production and their precocity in depositing muscles.

The objective of this study was to analyze colostrum and milk compositions of ewes kept in pasture receiving different types/levels of supplementation and to analyze milk composition variation throughout the initial third lactation period. After confirmation of pregnancy, 54 ewes were kept in pasture and supplemented from the final third of gestation until weaning with multiple mixture or concentrate (0.4% or 0.8% of body weight). Milk collections were carried out in the postpartum period to collect colostrum (day 0), and on the seventh, 14th, 21st and 28th milking days. Samples were obtained by manual milking and analyzed for protein, fat, casein, lactose, total solids and defatted dry extract. No effects from the different types of supplementation were observed on the colostrum composition or in relation to milk composition. An effect of supplementation was only found for lactose contents, which were higher for animals that consumed a higher level of supplementation. In relation to the milking days, a linear decrease in protein, casein, total solids and defatted dry extract contents was observed between the seventh and the 28th day of lactation. No interaction between type of supplementation and the milking days was observed. The different types of supplementation did not alter the colostrum composition of Santa Inês crossbred ewes, however they had an influence on milk composition. Protein, casein, total solids and defatted dry extract decrease linearly between the seventh and the 28th day of lactation.

This study was undertaken to examine biometric measurements during the growth phase of male and female Santa Inês sheep reared in Brachiaria brizantha pastures in northeastern Brazil. The experiment involved 24 castrated males and 24 females at an initial age of 90 days, with an average body weight of 19.04 ± 0.96 kg. Treatments consisted of the effect of four cultivars (Marandu, Xaraés, Piatã and Paiaguás) and two sexes. Six animals were used per treatment, in a randomized-block experimental design. The following characteristics were evaluated: abdominal circumference (AC), body condition score (BCS), body length (BL), body weight (BW), body capacity 1 (BC1), body capacity 2 (BC2), chest width (CW), heart girth (HG), leg circumference (LC), leg length (LL), rump height (RH), rump width (RW) and withers height (WH). Data were subjected to descriptive analysis, Pearson's correlation, ANOVA and Tukey's, Kruskal Wallis and Mann-Whitney tests. Univariate and multiple regressions were applied to estimate BW with a maximum error level of 5%. Significant differences were observed for the biometric measurements between sexes and cultivars (p70%) with AC, WH, CG, RW, BC1 and BC2. The male sheep grazed on cultivars Piatã showed the best values for BW (40.43 kg), HG, RW, WH, LL, LC (102.46; 20.8; 65.23; 60.44; 42.54 cm respectively) and BC1 (4.25 kg/cm). Females grazed on cultivar Marandu had higher values for RW, CW, LL (17.26; 20.1; 75.98 cm respectively), BC1 (6.03 kg/cm) and BC2 (0.422 kg/cm). The equations that best estimated live weight were BC1 and HG. In male and female Santa Inês sheep, biometric parameters grow differently depending on the cultivar where they are grazed during the growth phase. Cultivars Marandu and Piatã are the most recommended for sheep production, as they provided the best performance and body development in those animals.