<p><strong>Background.</strong> In terms of animal management, the measurement of body weight (BW) is important in the design of nutrition and health programs. <strong>Objective.</strong> The objective of the present study was to evaluate the relationship between body volume (BV) and BW in Pelibuey ewe lambs and ewes. <strong>Methodology. </strong>For the model development, the BW and body volume (BV) were recorded in 406 Pelibuey ewe lambs and ewes ranging from two months to one years in age. All animals were clinically healthy, with a BW = 37.62 ± 10.63 kg. The BV was calculated using the heart girt (HG) and the body length (BL). BV was calculated according to the mathematical formulas for calculating the volume of a cylinder, considering biometric measurements in the calculation. The relationship between BV and BW was assessed by linear (Eq. 1), quadratic (Eq. 2) and allometric equation (Eq. 3). The goodness of fit of the regression models was assessed by the Akaike information criterion (AIC), Bayesian information criterion (BIC), coefficient of determination (R<sup>2</sup>), mean square error (MSE) and root mean square error (RMSE). <strong>Results. </strong>The correlation coefficient (r) between BW and BV was 0.89 (<em>P</em> < 0.001). The quadratic model had the higher value of coefficient of determination (R<sup>2</sup>= 0.81, and the lower MSE (4.17), RMSE (2.04), AIC (1163.64) and BIC (1175.66) values. The predictive ability of the three live weight prediction models was evaluated using <em>k</em>-folds validation (<em>k</em> = 10). <strong>Implications.</strong> The quadratic model had the higher coefficient of determination and lowest values were found for the mean square error (MSE) and mean absolute error (MAE). This model is practical and predicts with high accuracy the BW of the animals. <strong>Conclusion.</strong> Based on the evaluation approaches used in the present study and the close relationship between BW and BV in Pelibuey ewe lambs and adult ewes, the quadratic model was the mathematical model that had the best performance according to the goodness-of-fit evaluation.</p>
<p><strong>Background. </strong>Guinea fowl (<em>Numida meleagris)</em> is used as an alternative for the production of meat with high nutritional value; however, there are several factors that affect their productive performance. <strong>Objective.</strong> Review the main factors that affect the productive performance of the guinea fowl described in the worldwide literature. <strong>Methodology.</strong> A bibliographic review in the databases of Scopus, NCBI, Springer, Science direct, Google Scholar, Redalyc, and other repositories was carried out. The keywords for the search were: Guinea fowl, <em>Numida meleagris</em>, productive performance and body weight gain. <strong>Results. </strong>The production system is one of the main factors that affect the productive performance of the Guinea fowl. Birds raised in semi-intensive conditions have better weight gains compared to those that are kept under an extensive system. Mortality in the extensive system increases due to poor or no disease prevention practices and natural predators. The increase in population density under intensive management conditions negatively affects the performance and welfare of Guinea fowl. Ignorance of the energy and protein requirements causes a deficient productive performance in weight gains. Genetic factors also play a role; in Africa local varieties that have not been genetically improved are bred in extensive systems obtaining low yields, compared to developing countries. Birds hatch from large eggs with shorter storage periods had better growth performance. <strong>Implications.</strong> There is limited information on the main aspects related to the raising of the Guinea fowl, including the factors that affect its productive performance. Ignorance of the productive parameters favors the displacement of Guinea fowl production by other poultry species, such as chicken.<strong> Conclusions. </strong>Breeding the Guinea fowl as an alternative for meat and egg production must be accompanied by the disclosure of productive parameters to improve their production performance.</p>
<p><strong>Background. </strong>Carcass yield varies depending on the relative proportions of muscle, fat and bone, therefore, the possibility of predicting its value would produce valuable information that will promote the viability and sustainability of rabbit meat production. <strong>Methodology.</strong> Thirty-eight male growing rabbits (New Zealand White × Californian) with body weights (BW) of 1329 ± 291 g and from 60 to 100 days of age were used. Real time ultrasonography (RTU) measurements were taken 12 h before slaughtering. For that, rabbits were shaved between the 6<sup>th</sup> and 7<sup>th</sup> lumbar vertebrae. The <em>longissimus thoracis et lumborum</em><em> </em>muscle (LM) area (LDA) and also the maximum LM width (LDW) and the maximum depth LM (LDD) were measured. Data recorded at slaughtering included carcass and non-carcass components. After chilling at 4° C for 24 hours, carcasses were split longitudinally to obtain left and right halves that were later weighed. Thereafter, the right half carcass was weighed and manually deboned for recording weights of muscle (TCM), and bone (TCB). <strong>Results.</strong> The highest correlation (r = 0.84, <em>P</em> <0.001) was observed between TCM and LDD, while the lower correlation (r = 0.4,<em> P</em> <0.001) was observed between TCB and LDW. The BW were highly related to carcass characteristics (r>0.77≤0.97). <em>In vivo</em> RTU measurements explained a low to moderate amount of variation in TCB and TCM with an r<sup>2 </sup>of 0.36 to 0.77 (<em>P</em> < 0.001) respectively. BW explained from 49 to 92% of variation in TCB and TCM, respectively. <strong>Implications.</strong> The <em>in vivo</em> ultrasound measurements it is a viable tool that allows predicting carcass value of rabbits.<strong> Conclusion. </strong>Our results indicated that the use of RTU measurements could accurately predict muscle from growing rabbit's carcass.</p>
<p class="SiMPLE">Background. The association of legumes with grasses improves the quality of the diet as well as the protein value, increases productivity, allows savings in nitrogen fertilizer and maintains the proportion of the botanical components of the meadow. The cutting date affects the productive behavior of the forages species in temperate, arid and semi-arid climate zones. Therefore, it is important to continue evaluating established grassland with legumes associated with grasses to generate information that will serve producers and increase the economic profitability of livestock activities. Objective. The objective of the present study was to evaluate the cutting date on dry matter production (PMD), growth rate (RG), botanical composition (BC), as well as relationships between RG and PMD and BC and PMD. Hypothesis. It is evident that the cutting date modifies the PMD, RG, as well as the relationship between RG and BC with PMD, but has no influence on BC. Methodology. Meadows irrigated with <em>Trifolium alexandrinum</em> L. associated <em>Lolium multiflorum</em> Lam. of a proportion of 40:60 sowing seeds, respectively subject to eight cutting dates (treatments): T<sub>1</sub> = 90 to 97 days elapsed between the sowing date and the first cut (DTS-PC), T<sub>2</sub>: 97 to 104 DTS-PC, T<sub>3</sub>: 104 to 111 DTS-PC, T<sub>4</sub>: 111 to 118 DTS-PC, T<sub>5</sub>: 118 to 125 DTS-PC, T<sub>6</sub>: 125 to 132 DTS-PC, T<sub>7</sub>: 132 to 139 DTS-PC and T<sub>8</sub>: 139 to 146 DTS-PC, under a randomized complete blocks design with four replicates. The trend of the factor under study (cutoff date) on the response variables was determined using orthogonal polynomials. Results. The DTS-PC caused a linear positive effect (P <0.001) of the evaluated species on the PMD and RG, observing that increasing the DTS-PC increased the PMD. (P = 0.0001). In contrast, no significant differences (P> 0.05) were observed in the BC. Regardless of the DTS-PC, the legume as <em>T. alexandrinum </em>contributed 64 % of the biomass, these percentages were determined dividing the PMD of <em>T. alexandrinum </em>by the PMD of <em>L</em>. <em>multiflorum</em> added with that of dead material and weeds. There was an effect of the DTS-PC on the relationship of RG:PMD (linear effect, P <0.01), while for the ratio relationships BC:PMD only a linear decrease was presented (P <0.01) at increasing the DTS-PC. Implications. The results of the present study contribute to knowing the productive parameters of a grass established with legume-grass in temperate, arid and semi-arid climate zones to improve the production of meat and milk. Conclusions. The elevation of the cutting date increased the PMD, but has an inverse effect for the relationships BC:PMD, as well as RG:PMD of each species. The highest RG was found at 97-104 DTS-PC for the evaluated species and dead material.</p>
<p><strong>Background</strong>: The identification of the relationship between the particular traits of the body development of the rabbit could help the understanding of the biological growth and the application in different areas of livestock and veterinary study. <strong>Objective</strong>. To evaluate the relationship between osteometry of the limbs, live weight (LW), hot carcass weight (HCW) and anatomical cuts; and generate equations to predict PV, PCC and anatomical cuts in New Zealand White (NZW) rabbits at different ages. <strong>Methodology</strong>. A total of 113 rabbits of seven different ages (9, 11, 14, 17, 20, 24 and 28 weeks) were used. The data obtained were LW, carcass characteristics: PCC and anatomical cuts (front, middle and back); and osteometry: length and diameter of the humerus (LH and DH), radio-ulna (LR-C and DR-C), femur (LF and DF) and tibia-fibula (LT-P and DT-P). The information was analyzed using Pearson's correlation coefficients (r) and linear and multiple regression models. The accuracy of the models was evaluated using the coefficients of determination (r2) and the square root of the mean square error (RCCME). <strong>Results</strong>. The correlations expressed between LW, carcass characteristics and bone lengths were higher (r= 0.90 – 0.95; p= < 0.0001) compared to diameters (r= 0.38 – 0.72; p= < 0.0001). The regression equations for PV had a RCCME that varied from 186.86 to 197.70 g using LR-C and LF. While for the PCC it presented RCCME from 130.4 to 138.58 g with LH, LR-C and DH. Regarding the anatomical cuts, the progressive order of rear, middle and front using LF and LH was RCCME= 21.66 to 25.67. The LF and LH explained 92 and 91% of the variation of the PV and PCC, although it decreased slightly in the anatomical cuts from 85 to 92%. <strong>Implications</strong>. The osteometry of the extremities reflects security in the application of equations to calculate general and particular data of body mass in the rabbit, this contribution of knowledge can be extrapolated for animal production and forensic veterinary studies. <strong>Conclusion</strong>. The close associations obtained between limb lengths (exception LT-P) with PV, PCC and anatomical cuts gave equations with high capacity to estimate these body changes of growing NZB rabbits.</p>
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