Najari Sghaier⁽¹⁾ Atoui Ahlem*⁽¹⁾ and Abdennebi Moldi⁽¹⁾

 (1). Institute of Arid Regions, Faculty of sciences (F.S.G) Gabés, University of Gabés, Médenine. Tunisia.

(* Corresponding author: Dr. Atoui Ahlem, E-mail : ahlematoui@gmail.com).

Received: 08/06/2020                               Accepted: 22/09/2020

Abstract

The study aimed to develop a set of indicators of an economic and biological nature that can be adopted from a better evaluation of the productivity of different genetic groups resulting from the local breeding program for goats with improved and specialized breeds in the oases of southern Tunisia. The proposed indicators depend on adjusting the average qualifications of milk and meat production for each genetic group, by taking into account the outcome of the breeding season and the cost of breeding for each group separately. The database was collected over a period of 22 years in the caprine herd of the Arid Areas Institute of Médenine. It consisted of direct records of 1,654 weights and 993 records of periodic milk production for members of the domestic goat herd, imported breeds, and hybrid groups. The proposed economic and vital indicators are based on collecting and adjusting all the components of milk production and growth of the goat by calculating the reproductive data, mortality, infertility and abortion. In the second stage, the productivity obtained above is modified by dividing it by the average metabolic weight (P ^0.75), which reduces the cost of breeding, which is correlated with the relative body size and feeding requirements in particular, which differ from one genetic group to another. The application of economic and biological indicators led to a classification and evaluation of productivity completely different from what was obtained based on a comparison of individual performance and production only as usual and which does not reflect the true effectiveness of the heterogeneous herds. It was noted that some strains, with high performance from milk products or heavy weights in weaning, were subject to evaluation influencing their ranking due to infertility rates or high mortality. Moreover, the correction by metabolic weight has profoundly altered the genetic difference arrangement in favor of local goats and marsiana with small sizes compared to latin, damascene and hybrid goats. Consequently, the incorporation of all productive components and animal behavior into the evaluation criteria provides effective technical means for comparing the productive performance of heterogeneous herds which supports the effectiveness of genetic improvement programs. Improvements can be made to the studied indicators by calculating other elements that interfere in the outcome of education or by adopting individual indicators instead of the medium, which is included in future studies.

Key words: Productivity assessment indicators, Local goats, Crossbreeding, Metabolic weight.

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