Informatics Publishing Limited

Khaleel Jawasreh ¹, Zuhair Bani Ismail ², Feizal Iya ¹, Castaneda-Bustos Vielka Jeanethe ³, Valencia-Posadas Mauricio ⁴

Affiliations
1 Department of Animal Production, Jordan University of Science and Technology, JO
2 Department of Veterinary Clinical Sciences, Jordan University of Science and Technology, JO
3 Department of Genetics and Biostatistics, National Autonomous University of Mexico, Ciudad Universitaria, CDMX 04510, MX
4 Department of Veterinary and Zootechnics, Life Sciences Division, Campus Irapuato-Salamanca, University of Guanajuato, Ex Hacienda El Copal, Irapuato, Guanajuato 36500, MX

Abstract

Aim: The aim of this study was to estimate the heritability, genetic and phenotypic correlations, and the genetic trends for pre-weaning growth traits including the birth weight (BWT), weaning weight (WWT), pre-weaning daily gain (PWDG), and weaning age (WA) in Awassi lambs.

Materials and Methods: A total of 5131 Awassi lambs from two Jordanian sheep breeding stations were used. A multitrait animal model and restricted maximum likelihood methods were used to estimate the covariances between the studied traits.

Results: The mean±standard deviation of BWT, WWT, PWDG, and WA was 4.48±0.8 kg, 17.13±0.7 kg, 0.2±0.07 g, and 65.5±0.7 days, respectively. Heritability estimates were 0.30±0.04 for BWT, 0.19±0.04 for WWT and PWDG, and 0.2±0.04 for WA. Positive genetic correlations were obtained between BWT and other traits, while negative correlations were obtained between WWT, PWDG, and WA (−0.50±0.12) and between WWT and WA (−0.67±0.14). The positive phenotypic correlation was obtained between WA and PWDG (0.63±0.01). The highest additive genetic variance was obtained for WA (34.58), while the lowest was estimated for PWDG (6.22E-04). The highest phenotypic variance was obtained for WA (175.5), while the lowest value obtained was for BWT (0.54). Maternal additive variance ranged between 0.13 and 0.03. The genetic trends were around zero for all studied traits.

Conclusion: Selection should be conducted using animals with high estimated breeding values through controlled breeding.

Keywords

Awassi Sheep, Breeding Values, Growth Traits, Heritability.

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Zuhair Bani Ismail ¹

Affiliations
1 Department of Veterinary Clinical Sciences, Jordan University of Science and Technology, Irbid-22100, JO

Abstract

The objective of this review article was to summarize the most recent clinical field trials that have been published evaluating the use of different types of vaccines against mastitis pathogens in dairy cows. Mastitis is one of the most common and economically important diseases in dairy cows in the world. The disease is considered an important welfare issue facing the dairy industry in addition to the loss of production and premature removal or death of affected cows. Losses are also related to high cost of veterinary medicines and the cost of unsalable milk of treated cows. Mastitis can be caused by either contagious or environmental pathogens both of which are best prevented rather than treated. In addition to the application of best management practices in the parlor during milking, vaccination against common udder pathogens is widely practiced in many dairy farms to prevent or reduce the severity of clinical mastitis. In this review, the most recent clinical field studies that evaluated the use of different types of vaccines in dairy cows are summarized.

Keywords

Dairy Cows, Immunization, Mastitis, Pathogens, Udder.

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