Reproductive Performance and Milk Production of Assaf Sheep in an Intensive Management System

Abstract

The Assaf breed of dairy sheep, a stabilized cross of the Awassi and East Friesian breeds, has replaced the Awassi as the breed of choice in its country of origin, Israel, and has spread to other Mediterranean countries. In Israel the Assaf breed is managed under an intensive production system involving weaning lambs at birth, rearing them artificially, and milking ewes after parturition. There are several breeding periods in the year when ewes are mated following hormonally synchronized estrus. Records of 18,976 lactations from 5 farms were analyzed to investigate factors that influenced Assaf milk and reproductive performance. Lactation curves were fitted to each lactation, and a range of parameters and calculated values were analyzed. Daily milk yield records also were analyzed to describe a typical Assaf lactation and compared with those of the Awassi breed. Factors affecting age at first lambing also were studied. An average Assaf ewe kept under this intensive management regimen was found to produce 334 L of milk during a 173-d lactation. Mean litter size was 1.57 lambs/ewe lambing, and lambing interval was 272 d. Milk production was affected by litter size, with twin- and triplet-bearing ewes producing approximately 20 L more milk per lactation than single-bearing ewes. Day length was the major environmental variable influencing milk yield. The difference between midsummer and midwinter day lengths accounted for a difference in daily milk yield of 0.44 L in favor of summer. Ewe lambs that were mated for the first time at later ages produced more lambs and more milk due to greater early lactation characteristics. Milk production was found to be negatively associated with subsequent reproductive performance. Comparing these results with those from an earlier study in the Awassi breed, the Assaf was found to produce less milk during a shorter lactation than the Awassi, but its greater litter size made it a more profitable breed.

Factors affecting milk yield and ewe's lactation curves estimated with test-day models

“…On the contrary, it was higher in comparison with Florina (Christodoulou et al, 1997) and Cine Type sheep (Karaca et al, 2000) classified as multipurpose breeds. Daily milk yield of Lacaune, although higher than daily milk yield of Tsigai and Improved Valachian, was lower than daily milk yield of comparable breeds reported in the literature -East Friesian (Hamann et al, 2004), Assaf (Pollot and Gootwine, 2004) and Lacaune (Barillet et al, 2001;Berger, 2004). The lower milk yield of Lacaune kept in Slovakia is probably a result of different feeding level and insufficient adaptability to different management and environmental conditions that do not allow the outstanding genetic potential to be manifested.…”

“…Contrariwise, small differences (only 4% for both breeds) observed when daily milk yields of Tsigai and Improved Valachian ewes were compared with previous analyses based on the test-day approach (Oravcová et al, 2005) indicate that the phenotype selection of the last years (since 2000) was not reflected in higher milk yields. Average daily milk yield of Tsigai and Improved Valachian breeds was much lower than daily milk yield of dairy breeds like East Friesian (Hamann et al, 2004), Assaf (Pollot and Gootwine, 2004), Churra Gonzalo et al, 1994;El-Saied et al, 1998;Fuertes et al, 1998), and also Bovec, Istrian Pramenka (Komprej et al, 2003), Black-Faced and Blond-Faced Latxa (Gabina et al, 1993), and Sfakia (Kominakis et al, 2001). On the contrary, it was higher in comparison with Florina (Christodoulou et al, 1997) and Cine Type sheep (Karaca et al, 2000) classified as multipurpose breeds.…”

Accurate mathematical models to describe the lactation curve of Lacaune dairy sheep under intensive management

“…Descriptive study of the Lacaune lactation curve and biological interpretation As previously reported in Lacaune sheep (Hernandez et al, 2011) and Asaff sheep (Pollott and Gootwine, 2004), the mean milk yield per lactation and the length of lactation decreased with lactation number, that is, with the age of the sheep. The decrease between lactations 1 and 2 was slight, but it increased from lactation 2 onward.…”

“…Most of them deal with ewes under experimental conditions (Groenewald et al, 1995;Portolano et al, 1996) or management conditions with suckling periods (Ruiz et al, 2000;Oravcová et al, 2006). Not many studies have been conducted under intensive farm conditions (Pollott andGootwine, 2000 and2004).…”

Effects of a Long Daily Photoperiod on Milk Yield and Ovarian Activity of Saanen Goats in Northern Mexico

“…environmental variable influencing milk yield in both sheep (Pollott and Gootwine, 2004; a long photoperiod (I6 to '' Of light) Hernandez et aZ., 2007) at northern latitudes, established lactation (Dahl et al, 1997) or dry a management strategy for dairy goat documented* day length is a barely investigated. Therefore, the objective of this study was to evaluate the effect of long- …”