Non-genetic sources of variation of milk production and reproduction and interactions between both classes of traits in Sicilo-Sarde dairy sheep

Abstract

This work aimed to study the sources of variation in productive and reproductive traits of the dairy Sicilo-Sarde ewes and to further investigate the interaction between both classes of traits. After edits, a database containing 5935 lactation records collected during 6 successive years in eight dairy flocks in the North of Tunisia was used. Total milked milk (TMM) in the milking-only period was retained as productive trait. The interval from the start of the mating period to the subsequent lambing (IML) and the lambing status (LS) were designed as reproductive traits. Sicilo-Sarde ewes had an average TMM of 60.93 l (±44.12) during 132.8 days (±46.6) after a suckling period of 100.4 days (±24.9). Average IML was 165.7 days. In a first step, the major factors influencing milk production and reproductive traits were determined. The significant sources of variation identified for TMM were: flock, month of lambing, year of lambing, parity, suckling length, litter size and milking-only length. Flock × month of the start of the mating period, parity, year of mating and litter size were identified as significant factors of variation for IML, while flock × month of the start of the mating period, parity and year of mating were identified as significant sources of variation for LS. In a second step, variance components were estimated using a three traits threshold mixed model, which combined LS as categorical trait and TMM and IML as continuous traits. Repeatability estimates were 0.21 (±0.03) for TMM, 0.09 (±0.02) for IML, and 0.10 (±0.05) for LS. Moreover, TMM and IML were found to be favorably associated for the flock × year of lambing effect (−0.45 ± 0.18) but unfavorably associated for the animal effect (0.20 ± 0.09).

Revue des connaissances sur la micro-filière ovine laitière en Tunisie : état des lieux et perspectives de relance de la race sicilo-sarde

“…(Selmi et al, 2009). Par ailleurs, une caractérisation préliminaire de la relation entre la production laitière et la reproduction des brebis sicilo-sardes (Aloulou et al, 2011), confortée par les travaux de Meraï et al (2014), a permis de confirmer l'antagonisme de ces deux caractères chez les ruminants laitiers (Bodin et al, 1999). Il faudra donc être attentif à ne pas détériorer les performances de reproduction lorsqu'on cherchera à améliorer la productivité laitière.…”

Lactation Performance of Small Ruminants in the Maghreb Region

“…A recent study taken in the Sicilo-Sarde breed [80] showed an average of daily milk production of 0.46 L with a high variation between 0.10 and 2.40 L and a milk period of 132.8 days. This study shows also a similar milking-only length (139 ± 47 days) and suckling length (104 ± 22 days) to previous reports [81].…”

A Study of Body Weight and Milk Traits of Karadi Ewes – Sulaimani Governorate, Iraq

“…Many studies analyzing the factors affecting ewes' growth performance, milk yield and milk composition were reported (Al-Barzinji and Hassan, 2005; Antonič et al, 2013). The main factors were flock (Meraï et al, 2014;Everett-Hincks, et al, 2014;Rahimi et al, 2014), ewes age (Ramakrishanappa et al, 2015;Sezenler et al, 2016;Siddalingamurthy et al, 2017)…”