Carcass composition and physicochemical and sensory attributes of breast and leg meat from native Mexican guajolote (Meleagris g. gallopavo) as influenced by sex.

The aim of the study was to compare carcass composition and physicochemical and sensory attributes of breast and leg meat from native Mexican guajolote (Meleagris g. gallopavo) as influenced by sex. For this, slaughter weight and carcass characteristics of male (n=8) and female (n=8) guajolotes raised traditionally under extensive systems with similar housing and feeding conditions were recorded. Also, physical characteristics, proximate composition, the fatty acid profile, and sensory attributes were determined in breast and leg meat using standard procedures. The results showed that males had higher (P<0.001) slaughter weight, hot and cold carcass weights, and dressing percentage, as well as carcass part weights, while females had higher (P<0.001) abdominal fat weights than males. The lightness (L*), yellowness (b*), and drip loss values of breast meat, as well as redness (a*) and water-holding capacity values of leg meat, were significantly (P<0.05) influenced by sex. Male breast meat had higher (P<0.05) moisture content, crude protein, erucic acid (C22:1n9), ∑ MUFAs (total monounsaturated fatty acids), ∑ UFAs (unsaturated fatty acids), ∑ DFAs (desirable fatty acids), ∑ UFA / ∑ SFA (total saturated fatty acid) ratio, ∑ PUFA (total polyunsaturated fatty acid) / ∑ SFA ratio, and chewiness scores than females. Likewise, leg meat from males showed higher (P<0.05) ash content, myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1n9c), palmitoleic acid (C16:1n7), ∑ SFAs, ∑ OFAs (odd fatty acids), thrombogenic index, and atherogenic index, whereas females had high fat content. In conclusion, it would be suggested that, from a nutritional point of view, the meat from male guajolotes was preferable to the meat from females.

Estimation of body weight using body measurements in female water buffaloes reared in southeastern Mexico.

Buffalo farming is an important livestock activity in Mexico. However, the low technological level of the farms makes it difficult to monitor the growth rates of the animals. The objectives of this study were to analyse the body measurements of 107 adult female Murrah buffaloes, to estimate the interrelationships between those measurements and body weight, and to develop equations to predict body weight (BW) using body measurements including withers at height (WH), rump height (RH), body height (BH), heart girth (HG), abdominal girth (AG), pelvic girth (PG), body length (BL), girth circumference (GC), diagonal body length (DBL), pelvic circumference (PC), and abdomen circumference (AC). The study was conducted on two commercial farms in southern Mexico. Pearson correlation and stepwise regression techniques were used for the data analysis. To find out the best regression models, we used model quality criteria such as coefficient of determination (R2), adjusted R2 (Adj.R2), root mean square error (RMSE), Mallow's Cp, Akaike's information criteria (AIC), Bayesian information criteria (BIC), and coefficient of variation (CV). Correlation results indicated that BW had a positive high correlation (P < 0.01) of all the measured traits. Model 4 (-780.56 + 311.76GC + 383.51DBL + 51.82PC + 47.65AC-106.78BL) was the best regression model with a higher R2 (0.87), Adj. R2 (0.86) smaller Cp (4.24), AIC (749.19), BIC (752.16), and RMSE (36.91). The current study suggests that GC, DBL, PC, AC, and BL might be used in combination to estimate BW of adult female Murrah buffaloes.

Models to predict live weight from heart girth in crossbred beef heifers.

The objective of this study was to develop and evaluate linear, quadratic, and exponential mathematical models to predict live weight (LW) from heart girth (HG) in crossbred heifers raised in tropical humid conditions in Mexico. Live weight (363.32 ± 150.88 kg) and HG (166.83 ± 24.88 cm) were measured in 400 heifers aged between 3 and 24 months. Linear and non-linear regression was used to construct the prediction models. The goodness of fit of the models was evaluated using the Akaike information criterion (AIC), the Bayesian information criterion (BIC), coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). In addition, the developed models were evaluated through internal and external cross-validation (k-folds) using independent data. The ability of the fitted models to predict the observed values was evaluated based on the root mean square error of prediction (RMSEP), R2, and mean absolute error (MAE). The correlation coefficient between LW and HG was r = 0.98 (P < 0.001). The quadratic model showed the lowest values of MAE (736.57), RMSEP (27.13), AIC (3783.95), and BIC (3799.91). Additionally, this model exhibited better goodness-of-fit values regarding external and internal validation criteria (higher R2 and lower RMSEP and MAE), thus having better predictive performance. The RMSE represented about 8% of the observed LW. Heart girth is highly correlated (r = 0.98) with LW. The quadratic model showed a high predictive capacity for crossbred heifers kept in tropical conditions.

Fatty Acids Profile and Healthy Lipids Indices of Native Mexican Guajolote Meat Treated to Two Heat Treatments.

Meat is a complex food with a structured nutritional composition that makes it an essential component of the human diet. In particular, the meat of native guajolote that is traditionally raised in natural conditions is an important dietary source of proteins of high biological value for the rural population of Mexico. The study aimed to evaluate fatty acids (FAs) profile and nutritional indices of breast and leg meat of native guajolote subjected to two heat treatments. For the study, a total of sixty muscle samples (30 breast meat and 30 leg meat) from adult male native guajolotes were used. The FA profile and nutritional indices were evaluated in raw meat (control) and meat subjected to two heat treatments (boiled and baked). The heat treatments, independently of the type of muscle, increased (p ≤ 0.05) the concentration of saturated (SFA) and monounsaturated FA (MUFA); in contrast, polyunsaturated FA (PUFA) decreased. Likewise, the dietary FA index, which has a negative hypercholesterolemic effect, and the atherogenic index increased in guajolote meat from the effect of the heat treatments, while the essential and undesirable hypercholesterolemic FA indices decreased. In conclusion, heat treatments increase the content of SFA and MUFAs in breast and leg meat of native guajolote. Boiling or baking the meat deteriorates PUFAs but increases the nutritional indices. The present investigation would provide valuable information for the guajolote meat product processing.

Using Post-Mortem Measurements to Predict Carcass Tissue Composition in Growing Rabbits.

The objective of this study was to determine post-mortem measurements for predicting carcass traits in growing rabbits. A total of 50 clinically healthy New Zealand White × Californian male rabbits with a body weight (BW) of 1351 ± 347 g between 60 to 80 days of age were used. Body weight was recorded 12 h before slaughtering. Data recorded at slaughtering included carcass weights (HCW). After cooling at 4 °C for 24 h, carcasses were weighed (CCW) and then were carefully split longitudinally with a band saw to obtain left and right halves. In the right half carcass, the following measurements were recorded using a tape measure: dorsal length (DL), thoracic depth (TD), thigh length (TL), carcass length (CL), lumbar circumference (LC). The compactness index (CCI) was calculated as the CCW divided by the CL. Thereafter, the right half carcass was weighed and manually deboned to record weights of muscle (TCM), and bone (TCB). The CCI explained of 93% of variation for TCM (R2 = 0.93 and a CV = 9.30%). In addition, the DL was the best predictor (p < 0.001) for TCB (R2 = 0.60 and a CV = 18.9%). Our results indicated that the use of carcass measurements could accurately and precisely (R2 = ≥ 0.60 and ≤0.95) be used as alternatives to predict the carcass tissues composition in growing rabbits.

Study of racial profile of the native Guajolote (Meleagris gallopavo gallopavo) in two regions of Mexico: morphometric characterization.

The present study aimed at the morphometric characterization of the native Guajolote reared in two regions of Mexico using multivariate analysis techniques. Data from a total of 362 unrelated native Guajolotes (257 males and 105 females) were used: of these, 160 were from the Central region and 202 were from the Southeast region. The birds were also grouped according to age, as youngs (≤ 8 months; n = 150) and adults (≥ 9 months; n = 212). The body weight (BW) and nine morphometric measurements-chest circumference (CC), body length (BL), body height (BH), neck length (NL), peak length (PL), shank length (SL), shank diameter (SD), wing length (WL) and wing width (WW)-were measured. There were significant differences (p < 0.05) due to the effect of region, sex and age for most of the morphometric measurements evaluated. There was a high percentage of positive and significant correlations (p < 0.001; p < 0.01) between the variables. In each region, three principal components were extracted that represented more than 75% of the accumulated variation among the variables. The most discriminating morphometric measurements between populations were WW, PL and NL. The Mahalanobis distance between the males and females of the two populations was 37.457 and 29.310 (p < 0.001), respectively. This differentiation can contribute to the definition of the phenotypic standard of this poultry genetic resource for its official recognition as a breed, as well as in the orientation of its genetic improvement programs in the future.