Artificial Haemonchus contortus infection as a strategy to induce protective immune response to natural infection in Pelibuey lambs.

The objective of this study was to evaluate the reduction in nematode faecal egg count (FEC) in Pelibuey lambs segregated as resistant (RES), susceptible (SUS) and intermediate (INT) to gastrointestinal nematodes. Twenty-nine weaned Pelibuey lambs, aged five months old, free of nematode infection, were used. Nine lambs were RES, six were SUS and 14 were INT lambs. The study consisted of two phases: in Phase 1 the lambs were infected experimentally with Haemonchus contortus. In Phase 2, the lambs were naturally infected by grazing. Faecal and blood samples were taken every week. The packed cell volume and total protein were quantified. The FEC value (FECmax) per lamb was recorded together with a natural reduction in FEC in the two phases. The data were analysed with a model of measures repeated over time. During Phase 1, the RES lambs showed the lowest FEC (1061 ± 1053) compared to the other groups (INT: 2385 ± 1794 eggs per gram of faeces (EPG); and SUS: 3958 ± 3037 EPG). However, in Phase 2 no significant differences (p > 0.05) were observed between the groups of lambs (RES: 275 ± 498 EPG; SUS: 504 ± 1036 EPG; and INT: 603 ± 1061 EPG). At the end of Phase 1, the FEC of RES lambs was naturally reduced by 75.5% in respect to FECmax (p < 0.05), and at the end of Phase 2 the reduction in FEC was 90% in respect to FECmax (p > 0.05); the same behaviour was observed in RES and SUS lambs. It is concluded that the artificial infection in the lambs induced a more rapid immune response in RES than SUS lambs, and all lambs developed high acquired resistance by continuous infection.

Influence of gender on carcass yield of twin lambs Blackbelly x Pelibuey at 56 days of age / Influência do gênero no rendimento de carcaça em cordeiros gêmeos Blackbelly x Pelibuey aos 56 días de idade

The aim of this study was to determine the influence of gender on pre-weaning growth, yield and weight of primal cuts of the carcass of Blackbelly x Pelibuey lambs. 16 twin lambs were used. The lamb gender was the fixed factor. The variables evaluated were: body weight at birth and at weaning, average daily weight gain, weight and yield of carcass and primal cuts: neck, arm, thorax, abdomen and leg. Gender did not affect (P>0.05) body weight at birth. However, the pre-weaning average daily weight gain and body weight at weaning were affected (P<0.05) by the gender. Hot carcass yield and weight and primal cuts were not affected (P>0.05) by the gender of the lamb. Nevertheless, the area of the Longissimus dorsi muscle and cavity fat were different between males and females (P<0.05) 11.5±0.73cm2 and 198±0.05 g vs 9.3±0.73cm2 and 282±0.05g, respectively. In conclusion, in twin lambs Blackbelly x Pelibuey males had greater average daily weight gain and body weight at weaning than females. Carcass yield and weight and primal cuts were not affected by the gender of the lamb. However, males had greater area of the L. dorsi muscle than females and these in turn had a greater amount of cavity fat than males.(AU)

Objetivou-se determinar a influência do gênero no crescimento pré-desmame, no rendimento e no peso dos cortes primários de carcaça de cordeiros Blackbelly x Pelibuey. Utilizaram-se 16 cordeiros gêmeos. Os dados foram analisados em um desenho completamente ao acaso, em que o gênero dos corderos foi o fator fixo. As variáveis avaliadas foram: peso vivo ao nascimento e ao desmame, ganho diário de peso, peso e rendimento de carcaças e dos cortes primários: pescoço, braço, tórax, abdômen e perna. O gênero não afetou (P>0,05) o peso vivo ao nascimento. No entanto, o ganho diário de peso e o peso vivo ao desmame foram afetados, sendo esses valores superiores nos machos (P<0,05). O peso e o rendimento das carcaças quentes e dos cortes primários não foram afetados (P>0,05) pelo gênero do cordeiro. Entretanto, a área do músculo Longissimus dorsi e a gordura cavitária foram diferentes entre machos e fêmeas (P<0,05): 11.5±0.73cm2 e 198±0.05g vs. 9.3±0.73cm2 e 282±0.05g, respectivamente. Em conclusão, nos cordeiros gêmeos Blackbelly x Pelibuey, os machos tiveram maior ganho diário de peso e maior peso vivo ao desmame do que as fêmeas. O peso e o rendimento da carcaça bem como os cortes primários não foram afetados pelo gênero do cordeiro. Todavia, os machos tiveram maior área do músculo L. dorsi que as fêmeas e estas tiveram maior quantidade de gordura cavitária que os machos.(AU)

Influence of gender on carcass yield of twin lambs Blackbelly x Pelibuey at 56 days of age / Influência do gênero no rendimento de carcaça em cordeiros gêmeos Blackbelly x Pelibuey aos 56 días de idade

The aim of this study was to determine the influence of gender on pre-weaning growth, yield and weight of primal cuts of the carcass of Blackbelly x Pelibuey lambs. 16 twin lambs were used. The lamb gender was the fixed factor. The variables evaluated were: body weight at birth and at weaning, average daily weight gain, weight and yield of carcass and primal cuts: neck, arm, thorax, abdomen and leg. Gender did not affect (P>0.05) body weight at birth. However, the pre-weaning average daily weight gain and body weight at weaning were affected (P 0.05) by the gender. Hot carcass yield and weight and primal cuts were not affected (P>0.05) by the gender of the lamb. Nevertheless, the area of the Longissimus dorsi muscle and cavity fat were different between males and females (P 0.05) 11.5±0.73cm2 and 198±0.05 g vs 9.3±0.73cm2 and 282±0.05g, respectively. In conclusion, in twin lambs Blackbelly x Pelibuey males had greater average daily weight gain and body weight at weaning than females. Carcass yield and weight and primal cuts were not affected by the gender of the lamb. However, males had greater area of the L. dorsi muscle than females and these in turn had a greater amount of cavity fat than males.(AU)

Objetivou-se determinar a influência do gênero no crescimento pré-desmame, no rendimento e no peso dos cortes primários de carcaça de cordeiros Blackbelly x Pelibuey. Utilizaram-se 16 cordeiros gêmeos. Os dados foram analisados em um desenho completamente ao acaso, em que o gênero dos corderos foi o fator fixo. As variáveis avaliadas foram: peso vivo ao nascimento e ao desmame, ganho diário de peso, peso e rendimento de carcaças e dos cortes primários: pescoço, braço, tórax, abdômen e perna. O gênero não afetou (P>0,05) o peso vivo ao nascimento. No entanto, o ganho diário de peso e o peso vivo ao desmame foram afetados, sendo esses valores superiores nos machos (P 0,05). O peso e o rendimento das carcaças quentes e dos cortes primários não foram afetados (P>0,05) pelo gênero do cordeiro. Entretanto, a área do músculo Longissimus dorsi e a gordura cavitária foram diferentes entre machos e fêmeas (P 0,05): 11.5±0.73cm2 e 198±0.05g vs. 9.3±0.73cm2 e 282±0.05g, respectivamente. Em conclusão, nos cordeiros gêmeos Blackbelly x Pelibuey, os machos tiveram maior ganho diário de peso e maior peso vivo ao desmame do que as fêmeas. O peso e o rendimento da carcaça bem como os cortes primários não foram afetados pelo gênero do cordeiro. Todavia, os machos tiveram maior área do músculo L. dorsi que as fêmeas e estas tiveram maior quantidade de gordura cavitária que os machos.(AU)

Estimation of genetic parameters for productive life, reproduction, and milk-production traits in US dairy goats.

Heritabilities and correlations for milk yield (MY), fat yield (FY), protein yield (PY), combined fat and protein yield (FPY), fat percentage (F%), protein percentage (P%), age at first kidding (AFK), interval between the first and second kidding (KI), and real and functional productive life at 72mo (FPL72) of 33,725 US dairy goats, were estimated using animal models. Productive life was defined as the total days in production until 72mo of age (PL72) for goats having the opportunity to express the trait. Functional productive life was obtained by correcting PL72 for MY, FY, PY, and final type score (FS). Six selection indexes were used, including or excluding PL72, with 6 groups of different economic weights, to estimate the responses to selection considering MY, FY, PY, and PL72 as selection criteria. The main criteria that determined the culling of a goat from the herd were low FS, MY, and FY per lactation. Heritability estimates were 0.22, 0.17, 0.37, 0.37, 0.38, 0.39, 0.54, 0.64, 0.09, and 0.16 for PL72, FPL72, MY, FY, PY, FPY, F%, P%, KI, and AFK, respectively. Most genetic correlations between the evaluated traits and PL72 or FPL72 were positive, except for F% (-0.04 and -0.06, respectively), P% (-0.002 and -0.03, respectively), and AFK (-0.03 and -0.01, respectively). The highest genetic correlations were between FPL72 and MY (0.39) and between PL72 and MY (0.33). Most phenotypic correlations between the traits evaluated and FPL72 and PL72 were positive (>0.23 and >0.26, respectively), except for F% (-0.004 and -0.02, respectively), P% (-0.05 and -0.02), KI (-0.01 and -0.07), and AFK (-0.08 and -0.08). The direct selection for PL72 increased it by 102.28d per generation. The use of MY, FY, PY, KI, or AFK as selection criteria increased PL72 by 39.21, 27.33, 35.90, -8.28, or 2.77d per generation, respectively. The inclusion of PL72 as selection criterion increased the expected response per generation from 0.15 to 17.35% in all selection indices studied.

Comparison of parasitological and productive traits of Criollo lambs native to the central Mexican Plateau and Suffolk lambs experimentally infected with Haemonchus contortus.

The study compares the parasitological and productive traits of Criollo lambs native to the central Mexican Plateau (CNCMP) and Suffolk (SU) lambs experimentally infected with Haemonchus contortus. CNCMP lambs (n=20) and SU lambs (n=15) were infected with L3 of H. contortus while five lambs of each genotype were kept as controls. Fecal egg count (FEC), packed cell volume (PCV), blood eosinophil number (BEN), ocular mucous membrane color (as measured by the FAMACHA index), changes in body condition score (BCS) and cumulative live weight gain (CLWG) were measured weekly during a 20-week period. On week 20, all animals were euthanized and the number of adult worms (AW) in the abomasum was counted. Infected SU lambs had higher (p<0.05) FEC and AW mean values compared to CNCMP lambs, which had a higher mean BEN count (p<0.05). Infected lambs had lower PCV values than controls, regardless of genotype, and had a negative correlation (r=-0.84, p<0.05) with the FAMACHA index. BCS tended to decline for infected SU lambs and increased slightly for infected CNCMP lambs. CLWG differed in all groups (p<0.05); infected SU lambs gained 12.1+/-1.9kg, infected CNCMP lambs gained 18.8+/-0.7kg, control SU lambs gained 34.6+/-1.6kg, and control CNCMP lambs gained 26.9+/-0.8kg. In conclusion, CNCMP lambs had a smaller worm burden, a better ability to maintain their productive traits, and were less affected by infection with Haemonchus contortus.