THE EFFECT OF BODY WEIGHT AND LITTER SIZE ON SOME PRODUCTIVE PARAMETERS AND MILK COMPONENTS OF SHEEP UNDER SEMI – INTENSIVE BREEDING

In the current study, 28 Awassi ewes (2-3 aged) years aged were used with their lambs for 12 weeks, to evaluate the effect of ewes body weight (BW) and Litter size (LS) on Body weight BW, Body gain (BG) of lambs, Milk yield (MY) and milk components of ewes. After lambing, ewes were weighted directly. Ewes distributed to 4 groups depending on it's body weight, the groups were: 1 st and 2 nd groups: ewes with high body weight and single lambing (HS), and twin lambing (HT) respectively, 3 rd and 4 th groups: ewes with low body weight and single lambing LS, and twin lambing LT respectively. The results showed a significant increase (p≤0.05) in BW and BG in HS lambs groups compared with LT lambs most weeks of study. MY was higher significantly (p≤0.05) in Heavy ewes group that have twin lambs at most weeks of study, milk fat% recorded a significant increase in milk fat% in Heavy ewes group with single lamb. In conclusion, single lambs born and reared by heavy ewes were became heavier at the end of lactation period (at weaning), also ewes with twin lambs regardless if it was heavy or light will have more milk yield.


INTRODUCTION
High lambing rate is the biggest contribute to get more profits from sheep farms. However, lamb's survivability is an important issue in highly fecund sheep flocks (8). In lambs meat production systems, ewes play a double role, they contribute directly to the number of lambs sold through their litter size, and indirectly, through the socalled maternal components, to the survival and growth of the lambs (Bardford,1972).Sheep farming has been developing, mainly due to the growth of production and consumption of high quality sheep meat (Sosa,2008), which is considered an attractive source of income to farmers. Many factors may influence the lambs development, which included year and type of birth , weight of dam and milk yield, in addition to feeding conditions (Acta and Dogan,2014;Abdul-Noor, 2002,;Gaskins, et al, 2005;Notter, et al, 2005 andRashidi, et al, 2008). (Merkhan, (20019), reported a relation between body and udder measurements to be moderately and strongly associated with milk productions. This environmental factors had a significant effect on body weight of lambs at various ages through the available of space in uterine during pregnancy, nutrient supplies and competition for milk after birth especially with twins (Hasan and Seyed, 2009). Also birth and weaning weights of lambs were usually influenced by physiological, environmental and genetic factors, environmental factors including ewes age, litter size and growth type (Notter, et al, 2005). Milk is the sole source of nutrients for the 16 newborn mammals, thus, its survival and potential to reach reproductive maturity are directly depend upon the lactational success of it's dam. Many environmental factors applied postnatally are known to affect milk production of the dam (Walker, et al, 2004 andPulina, et al 2006).
The present study was undertaken to assess effect of body weight and litter size on some productive parameters and milk components of Awassi ewes.

MATERIALS AND METHODS
The study was carried out at Bibokht village which located northeast Mousl city, during the period 1/10/2017 to 1/1/2018, to evaluate the effect of body weight and litter size on some productive parameters of lambs, milk yield and components of ewes. The study include 28 pregnant Awassi ewes (2-3 years aged). The animals were housed in semi-open pens ( 24 m 2 for each group), the animals were examined by the veterinarian and were healthy , disease-free and were supervised by veterinarians throughout the study period with all the required vaccines. Ewes divided randomly to 4 groups depending on it's body weight heavy (44.73 -46.17 kg) or light (36.22 -37.15 kg) and litter size single or twin lambing, the groups were: 1st group: ewes with high body weight and single lambing HS, 2nd group: ewes with high body weight and twin lambing HT,3rd group: ewes with low body weight and single lambing LS, 4 th group: ewes with low body weight and twin lambing LT. The concentrated ration was mentioned in (Table 4). Ration admitted to the animals at a rate of 1500 g/animal/day, and the animals of each group were fed collectively, drinking water was freely available during the study period. The amount of milk measured every 15 days twice daily at two consequentive days using manual milking method.  Al-Khawaja, et al,(1978).
The milk was analyzed using an Eko-milk analyzer, the analysis includes fat, protein, lactose and non-solid fat%. Data were analyzed using the General Liner Model (GLM) procedure (Anonymous, 2002) assuming the following model: Differences among means were tested using Duncan multiple rang test (Steel and Torrie, 1984).

RESULTS AND DISCUSSION
The results of the effect of body weight heavy (H) or light ( L) and litter size single (S) or (T) on body weight (BW) and body gain (BG) of Awassi lambs are presented in (Table 2), whose showed a significant increase in BW of H and S lambs at most weeks of treatment, as compared with L and T lambs. Table 2 also revealed a significant increase (P≤0.05) in BG of H and S lambs at most weeks of treatment. Values of milk yield (gm), milk fat% and milk protein% of Awassi ewes are presented in (Table 3), and showed a significant increase in milk yield of H ewes as compared with L ewes, in most weeks of study, also there were a significant (P≤0.05) increase in milk yield at 4th, 6th, 8th, and 12th weeks in T ewes as compared with S ewes. Milk fat% increased significantly (P≤0.05) in S ewes as compared with T ewes, while reported a significant (P≤0.05) in ewes milk as compared with L ewes at most weeks of study. No significant effects were showed of body weight and litter size on milk protein% in all weeks of study except in 8th and 10 th weeks, there were a significant increase in H ewes as compared with L ewes and in T ewes as compared with S ewes. And in regard to milk lactose%, ewes with LS had significantly higher lactose% than ewes with LT at the 4th and 8th weeks of lactation, and higher milk lactose% was recorded in ewes with LT than in LS ewes at the 12th week of lactation, on the other hand, LS ewes had significantly higher milk lactose% as compared with HS ewes at (P≤0.05). For nonfat 18 solid% a significant increase in NFS in LS as compared with HS ewes and in LS ewes as compared with LT ewes at the 2nd week of lactation, and in HT ewes as compared with LT ewes at 6th week of lactation.
Single lambs heavier at lambing than twins, because of the reduced uterine space limits variance in birth weight (Gluckman and Hanson, 2004). Birth type (single or twin) affect the weights of lambs at lambing to weaning due to the single born lambs had better opportunities in the mother's wombs than the twins or triplets and were hence heavy at birth. (Babar, et al, 2003).
Live weight of lambs at birth increased in proportion to the increase of Live weight of ewes (Akta and Dogan, 2014). Results were in agreement with the results of (Aliyari, et al, 2012) who reported that ewes with the highest body weights produced lambs with highest body weights, this may be attributed to the better development of mammary (Santello, 2008), whose reported a significant increase in body weight and body gain at birth till weaning in Hampshire Down lambs. Twins present lighter weights at birth because of gland in heavy ewes than light ewes. The impact of litter size of current study are in agreement with the results of Barrose, et al (2005) and an intra-uterine competition. Single lamb's BW and BG were more than twins, because twins receive less milk than singles, Kalantar, (2003) and Matika et al, (2003), reported that type of birth have no significant effect on BW and BG. Also results of BW and BG were in agreement with the results of Saghi, et al, (2007), who reported that single borne lambs have higher birth weight and daily growth in comparison with multiple born lambs. Heavy ewes born lambs heavier than lambs born from light ewes, the reason of that may be in the body fat metabolism serving as a source for more milk yield in the heavy ewes (Corner et al, 2013). Heavy and twin lambing ewes produced more milk than light and single lambing ewes, this results was in agreement with Abdul-Noor, et al,2002;Al-Azzawi andAl-Rawi, 1997 andKassem et al, 2010, whom reported a significant increase in milk yield with high twinning rates, this increase attributed to the higher stimulation of twins rather than single lambing. Orhan et al, (2011), report no effects of birth type on milk fat, protein, lactose and total solids%.
In conclusion, body weights and body gain lambs, milk yield, milk fat% and milk protein%, increased significantly by the effect of the body weight and litter size. Heavy and twins lambing results more milk yield, while single lambs have a heavier weaning weights.