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University of Gezira (2015)

Phenotypic and Genetic Characteristics of Tagger Goats and Assessment of Other Ecotypes in the Gezira State, Sudan

Mohammed, Yassir Abdalla Ombabi

Titre : Phenotypic and Genetic Characteristics of Tagger Goats and Assessment of Other Ecotypes in the Gezira State, Sudan

Auteur : Mohammed, Yassir Abdalla Ombabi

Université de soutenance : University of Gezira

Grade : Doctor of Philosophy in Animal Breeding 2015

Résumé
Goat production system in the Gezira State is largely traditional with low inputs and outputs. It is based on many goat ecotypes including Nubian and Tagger of the Nuba Mountains. In view of the paucity of information on goat production in the Gezira, the objective of this study is to characterize local breeds and their production systems. In addition, to characterize Tagger goats phenotypically and genetically in the Goat Research Centre, Faculty of Agricultural Sciences, University of Gezira, Sudan. A questionnaire was used and analyzed statistically for local breeds in the Gezira State. The results of the questionnaire showed that most owners (53.40%) herded goats in mixed flocks with cattle, sheep and camels and 46.60% raised goats alone. Overall mean flock size was 105±6.5. Females had higher longevity (7.88±0.20 years) than males (6.32±0.24 years). Females kidded in autumn (63.60%), winter (20.30%) and summer (0.80%). Both age at puberty and at first service (months)were higher in males (8.04±0.20 and 9.03±0.21, respectively) than females (7.82±0.20 and 8.77±0.21, respectively). Mean age at first kidding, age at weaning and kidding interval were 13.77 ± 0.22, 2.64±0.06 months and 207.29 ± 2.16 days, respectively. Overall mean milk yield was 1.06 ± 0.03 kg/day. Most owners used an extensive production system (94.10%). Milk production was the main objective of goats rearing (45.80%). Most owners (83.10%) used own bucks for breeding. Tagger records for three generations (2007- 2011) of 42 males and 48 females were used to study genetic and non genetic factors. Overall Tagger body weight (BW) (kg) at 0, 4, 8 and 12weeks of age was 1.76±0.04, 4.25±0.12, 5.92±0.12 and 7.22±0.21, respectively. Singles were heavier (1.80±0.05 kg) than twins (1.74±0.05 kg) and males were heavier (1.78±0.06 kg) than females (1.73±0.05 kg). Heritability estimates of BW at 0, 8 and 12weeks were 0.46±0.66, 0.73±0.64 and 0.82±0.63, respectively. The highest genetic correlation was between BW at 8 and 12 weeks (0.94± 0.14) and the least was between birth weight and 8 weeks (0.02±0.90). Heritability of body condition score (BCS) was highest (0.80±0.63) at 8 weeks and least (0.54±0.65) at 4 weeks. Phenotypic correlations among BCS were highest between 4 and 8 weeks old and least between 4 and 12 weeks. Height at withers and body length heritabilities at 12 and 24 weeks were 0.37±0.66, 0.91±0.63 ; and 0.17±0.67, 0.01± 0.67, respectively. The study contributed to the characterization of goat ecotypes in the Gezira State and their production systems. Effective practices and selection strategies are needed to improve goat production in the State.

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Page publiée le 25 novembre 2018