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One thousand (1,000) sheep carcasses produced in Mexico were characterized. Data were processed through descriptive statistics and using a totally random design. From total carcasses, 82.2% were males and 17.8% females. Fifty three (53) genotypes (11 pure breeds and 42 different crosses) were identified. Slaughter weight averaged 43.2 ± 7.2 kg (20.4 to 85.7), cold carcass weight averaged 22.0 ± 4.1 kg (11.3 to 50.0) carcass yield was 50.0 ± 5.1% (34.7 to 73.5), rib eye area averaged 14.8 ± 3.8 cm² (2.7 to 29.7), subcutaneous fat thickness had a mean of 3.1 ± 1.6 mm (1.0 to 10.0) and pH averaged 5.5 ± 0.2 (5.0 to 6.5). The intensive production system showed higher values in slaughter weight, cold carcass weight and rib eye area (44.4 ± 5.9 kg, 22.8 ± 3.3 kg and 15.5 ± 3.6 cm², respectively) than the semi-intensive system (43.6 ± 5.3 kg, 19.9 ± 3.1 kg and 13.8 ± 2.5 cm²) and extensive system (36.4 ± 9.7, 19.6 ± 2.6 kg and 9.6 ± 2.6 cm²). Males had higher values than females in slaughter weight (44.3 ± 6.7 vs 40.1 ± 6.1 kg), cold carcass weight (22.2 ± 3.8 vs 21.2 ± 4.4 kg) and rib eye area (15.2 ± 3.7 vs 12.7 ± 3.7 cm²). The great diversity in phenotypes and different lamb conditions caused considerable variability in carcass traits, which limits the formal lamb market, so sheep domestic production should be reordered towards a more uniform quality condition. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the effects of sex of lamb (SL: male, female), type of birth (TB: single, twin), age of dam (AD: 2 to 7 years and older), farm (F: 10 units), and sire nested within farm, as well as first-order interactions that influence the variation of birth weight (BW), adjusted weaning weight (AWW) and average preweaning daily weight gain (ADG) of Hampshire lambs from 10 farms in Hidalgo, México. A data base from 2006 to 2009 with 998 observations for BW and 933 for AWW and ADG was analyzed. Feeding of parents and lambs was based on grains, alfalfa, oats hay, and minerals. The statistical analysis was carried out with the GLM procedure of SAS. Overall means were BW: 5.1±0.9 kg, AWW: 32.3±5.4 kg, and ADG: 0.300±0.055 kg. Significant effects (P<0.01) due to sex of lamb were observed in the three variables analyzed, males had the highest averages; type of birth (P<0.01) only on BW and AWW, the highest averages were obtained by lambs of single birth; age of dam on BW (P<0.01) and AWW and ADG (P<0.05), lambs born to dams from 3 to 5 and 7 years and older had the highest averages in the three variables. Sire nested within farm had a significant effect (P<0.01) on AWW and ADG. It is concluded that there are important environmental factors influencing pre-weaning traits of Hampshire lambs, useful information that must be considered for management purposes and genetic improvement in these farms. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the individual and flock serological frequency and detect the risk factors of C. abortus infection in seven Mexican sheep producing states. It was performed a multifactor, cross-sectional, and stratified study with an analysis of 5,321 serological samples from 323 flocks in 61 municipalities. Serology frequency was determined using a commercial ELISA kit. The risk factors associated with the disease were determined through surveys and statistical analyses with a squared Chi test and a 95% confidence interval. Of the 5,231 serum samples, 581 (10.92%) had positive ELISA test results. The results, by state, of positive sera were: Tlaxcala 13.08% (73/558); Sonora 12.45% (102/819); Chihuahua 11.56% (107/925); Hidalgo 11.34% (97/855); Chiapas 10.15% (60/591); Querétaro 9.69% (79/815); Estado de México 7.09% (63/758). The frequency of seropositive herds was 43.34% (140/323). The results, when grouped by state, were the following: Hidalgo 67.39% (31/46), Querétaro 67.18% (43/64); Sonora 40.92% (19/47); Tlaxcala 33.33% (12/36); Chiapas 31.57% (12/38); Estado de México 25.45% (14/55), and Chihuahua 24.32% (9/37). The main risk factors that favor the presence of ovine enzootic abortion are gestation, 37 to 48 mo of age, and an intensive production system. These serology studies identified the presence of ovine enzootic abortion in Mexico and some of the risk factors associated with this infection. [ABSTRACT FROM AUTHOR]