Body Condition Score (BCS) and Body Weight of Nellore Brown Sheep at Various Reproductive Stages in Different Systems of Rearing

In general, the ewe body weight has two components, the sheep basic skeletal size and the degree of fatness (body condition). The body weight alone cannot indicate the degree of fatness due to the difference in skeletal size between ewes. Therefore, BCS is an estimation of animal muscle and fat development and is associated with the direct measurement of back fat depth or the proportion of fat in the animal body which provides a better approximation than body weight alone (Russel et al., 1969).
       
Sheep body condition score determination is commonly used in the countries where sheep farming is well known. Applied as an express evaluation of the animal physiological condition and an ability to track and provide for their maximum nutrition, this approach has a significant influence on flock management (Slavova et al., 2015). BCS is a good body reserve prediction technique and is associated with seasonal variations in the availability of feed which are marked in tropical regions. At each stage of the reproduction cycle there is an optimum condition score for every ewe in the flock. Flock owners can make adjustments in the feed program by knowing BCS to save money for the reproductive stages or preventing ewe-related problems such as neonatal lamb mortality.
       
Sheep farmers show a keen interest in intensive system of rearing, due to the scarcity of grazing land and poor quality of pasture. But currently very little information available on performance of Nellore brown sheep under different systems of rearing. Therefore, the present study was carryout to know the BCS and Body weight of Nellore brown sheep in different systems of rearing.

Site of the study
 
The present study was conducted at Livestock Research Station, Mamnoor, Warangal district, Telangana state situated at an altitude of 290 meters above mean sea level on 79.59° longitudes and 17.9° latitude. The minimum and maximum temperature ranges from 16.2 and 42.9°C. The average annual rainfall of the area is 994 mm. Some rainfall during the summer and post monsoon months and it is mainly in the form of thunder storms.
 
Animals
 
Sixty Nellore brown ewes (1.5-2 years) were selected from Sheep unit for the present study. Three rams of average 2 years age were selected for tupping of ewes during study period. The animals were housed in well ventilated shed made up of asbestos sheet roofing with morum flooring and maintained under hygienic condition. The sheds were cleaned every day morning and lime was applied on the floor once in every fifteen days. The animals were provided with bore well water ad libitum for drinking purpose. The waterers were cleaned every day and filled with fresh water in the morning and evening. The ewes were dewormed at the starting of the study. Prophylactic measures against sheep pox, enterotoxaemia, pests des petits ruminants, blue tongue, hemorrhagic septicemia, endo and ecto parasitic infections were carried out as per the institution calendar to ensure animal health condition throughout the study period. The estrous ewes were identified by teaser rams in the morning and evening hours. The separated estrous ewes were tupped by designated rams and date of tupping were recorded.
 
Body weight recording
 
The body weight of the ewes were recorded at 7.30-8.30 am in the morning before offering feed by using platform balance. The weight of the animals were recorded at before breeding, every month during pregnancy and fortnight  interval from lambing of the animals  to weanning of lambs.
 
Body condition score (BCS)
 
BCS was assessed by careful palpation of the spinous and transverse process in the loin area, immediately behind the last rib. The BCS method descried by Russel (1984) was used to assess the animals with scale of 0-5. The BCS of the ewes were assessed at the same time of body weight recording.
 
Experimental procedure
 
The study was conducted for a period of more than 1 years from March 2019 to June 2020. All 60 ewes selected for the study was allotted to three rearing systems i.e intensive (G1), Semi- intensive (G2) and extensive (G3) system by using complete randomized design (3´20). In G1 group, the ewes were kept in the shed throughout the day provided with farm grown chaffed green fodders (APBN, CO-3 and 4, Super Napier, SSG and Hedge lucernae which ever available in the farm) in the morning and evening time, concentrate feed @ 1% of their body weight offered only in the evening time and not sent for grazing. The left over fodder and feed were removed from manger early morning every day. In G2 group, the ewes were sent for grazing for about 6 hours per day and offered 200 grams of concentrate feed in the shed in the evening time.  For G3 group ewes no concentrate feed were offered in the shed and sent for grazing for 8-10 hours per day. The concentrate feed offered to the ewes in G1 and G2 group contain CP - 17.3 per cent, TDN - 72 per cent.
       
The statistical significance of all body weight and BCS were analyzed as per the methods described by Snedecor and Cochran (1994).

Body weight of ewes before breeding
 
The mean body weight of ewes at the time of breeding was significantly (P<0.01) higher in G1 than G2 and G3groups, but the means of G2 and G3 group were not significantly differ in the present study (Table 1). Mukasa-Mugerwa et al., (1994), Thiruvenkadan et al., (2008) and Sivakumar et al., (2009) who reported similar body weights at the time of breeding in their studies. Kumar and Vasanthakumar (2016) who reported slightly contrary result, that the supplemented group had higher weight at breeding but had not significant difference with grazing animals.
 

 
BCS of ewes before breeding
 
At the time of breeding, the mean BCS of ewes in G1 (2.97±0.10) group was significantly (P<0.01) higher followed by G2 (2.47±0.10) and G3 (2.33±0.09) group (Table 2). Thomas et al., (1987) and Berhanu et al., (2013) reported higher BCS at the time of breeding in the supplemented group than non-supplemented group. Maurya et al., (2009), Sejian et al., (2010), Aliyari et al., (2012) and Vatankhah et al., (2012) recommended to maintain the BCS of ewes at breeding in a range of 3 to 3.5 to optimize profitability in breeds of their study. Abdel-Mageed (2009) and Yilmaz et al., (2011) recommended to maintain the BCS of ewes at breeding in a moderate condition (2.5 or 3) to optimize profitability of sheep flocks.
 

 
Based on the results of several researchers and present study, the BCS of the Nellore brown sheep at breeding may be targeted 2.5-3.0. In the present study, G1 and G2 group had reached targeted BCS at breeding contributes to higher conception rate, lambing rate, higher birth and weanning body weight of lambs. Due to lower BCS than targeted BCS, reproductive efficiency in the G3 group was lower than that of the G1 and G2 group.
 
Body weight ewes during pregnancy
 
The mean body weight of Nellore brown sheep in G1 group had higher body weight during pregnancy than other two groups (Table 1). In the first and second trimester of pregnancy, G2 group had higher mean body weight than G3 group and had no significance (P<0.01) difference between these two groups, but during last trimester of pregnancy had significance (P<0.01) difference between the groups. The growth of the foetal lamb accelerated during the final 6 weeks of pregnancy but in extensive system sufficient nutrients may not available to meet the requirements cause lower body weight than Semi-intensive system. Mukasa-Mugerwa et al., (1994), Chaturvedi et al., (2010), Sahoo et al., (2016) and Kumar and Vasanthakumar (2016) who studied on body weight during pregnancy reported that the supplementary feed fed sheep had higher weight than the grazing animals. Further, Thiruvenkadan et al., (2008) who reported similar body weights with present study in extensive rearing system during pregnancy.
 
BCS of ewes during pregnancy
 
Significantly higher BCS during pregnancy observed in the ewes of G1 group than G2 and G3 group but mean BCS of G2 and G3 are not comparable in the present study (Table 2). The BCS gain during pregnancy in G1, G2 and G3 group had 0.63±0.06, 0.53±0.06 and 0.44±0.11, respectively. Al-Sabbagh et al., (1995) who observed that the lambs born to pregnant ewes with BCS 2.5 and 3.0 had high birth weight than BCS 3.5. Álvarez Rodríguez et al., (2012) who reported that live weight (LW) and BCS gains from 1^st to 4^th month of pregnancy were greater in ewes with BCS<3.0 than in>3.0 animals of Churra Tensina breed. Kenyon et al., (2013) who found that lambs born to pregnant ewes had BCS 2.5 had lower survival rate (P<0.05) than BCS 3.0 lambs. BCS 3.0 ewes weaned a greater total weight of lamb (P<0.05) than BCS 2.5 pregnant ewes.
       
In the present study, G3 group had higher prenatal mortality than G1 and G2 group. Caldeira et al., (2007) who also reported lowest abortions for higher BCS range of 2.5- 3.0 against 1.5 BCS in ewes. It would be a high risk strategy to manage ewes to a low BCS during gestation as under nutrition in mid to late gestation can reduce fetal growth and birth weight of the lambs was reported by Kenyon et al., (2007). West et al., (1989) also reported higher prenatal mortality and Nordby et al., (1986) who reported higher neonatal mortality and Khan et al., (1994) lower lamb survival for the lambs born to the ewes with low BCS.  It warrants us the importance of BCS in relation to gestation from the profitable point of view in terms of lamb crop.
 
Based on the literature and the results of present study, the BCS of the Nellore brown sheep may be targeted during early to mid-pregnancy was 2.5-3.0 and in last trimester was 3.0-3.5.
 
Body weight of ewes during lactation
 
The average body weight of ewes in the present study falls between 28-31.5 kg before 48 hours of the lambing and 25-28 kg after 48 hours of lambing (Table 3). The similar values were reported by Mukasa-Mugerwa et al., (1994) and Tailor and Yadav (2012) in their studies. Ewes body weight in G1 group slowly loses from lambing to 6 weeks, then gain up to 12^th of lactation. But in G2 group, the ewes losses body weight throughout the lactation period. The loss of body weight in G3 group has been higher in the present study might be due to the ewes mobilize the body reserves in G2 and G3 group to meet the additional nutrient requirements for milk production, resulting in loss of body weight. These results were similar to Chaturvedi et al., (2010) and Kumar and Vasanthakumar (2016) who reported the non-supplemented ewes lost more body weight than supplemented group during lactation period. The body weight loss in G2 and G3 group during lactation period was between 2-2,5 kg and the same result reported by Naik et al., (2016).
 

 
BCS of ewes during lactation
 
The mean BCS of ewes in G1 group was higher than G2 and G3 group immediately after lambing, but G1 group had no significant (P<0.01) difference with G2 group (Table 4).  The BCS of the ewes at 12^th week of postpartum was 2.68±0.08, 1.96±0.04 and 1.62±0.08, respectively in G1, G2 and G3 group. The similar results reported by Anusha (2016) studied on Nellore brown sheep, the BCS of the ewes 2 weeks before lambing ranged from 2.50-4.00 with mean BCS 3.15 and the mean value of BCS at 1^st week post-partum 2.91, which was further decrease to 2.38 by 12^th week postpartum.
 

       
The loss of BCS in ewes of G1, G2 and G3 group from lambing to 12^th week of lactation was -0.32±0.01, - 0.64±0.08 and -0.77±0.07, respectively. The loss in the body condition in all groups could be attributed to the loss of body reserves by colostrums and milk feeding for the lambs until weaning. The current study trends in post parturient BCS loss indicated that the ewe flocks that had higher BCS during pregnancy had minimal loss in BCS after lambing.
       
Karakus and Atmaca (2016) who reported although not statistically significant (p<0.05), lambs born to ewes with the highest BCS at lambing (3.5) had higher live weights than lambs from BCS 2.5 and BCS 3.0 ewes between 30 and 120 days of age. Further, Mathias-Davis et al., (2013) who suggests that if farmers manage their ewes to achieve high BCS at lambing time, the growth of lambs upto weaning is likely to improve. This same results were observed in the present study by higher birth weight of lambs in G1 and G2 group than G3 group.
       
The ideal BCS at the time of lambing was 3.0-3.5 and for the care of adult ewe flock should not be less than BCS 2.0 after 12^th weeks of lactation or at the time of weanning. In comparison, G2 and G3 groups reported significant postpartum declines in BCS resulting in BCS below 2.0 at 12^th week of lactation. In G2 and G3group were not had sufficient forage and feed for compensating the losses due to parturition and milk drain after parturition.

BCS reflects the economic importance of the studies in terms of wastage of the supplementary feeding. Maintaining BCS of 2.5-3.0 at the time of breeding, 3.0 at early and mid-gestation, 3.5 at the time lambing and 2.5 at the time of weanning f lambs. In addition, using BCS as a method to identify ewes with low body condition scores at lambing time and preferentially feed them during lamb rearing is likely to be advantageous and increase the growth of their lambs.