Various Effects of Concentrate Feed Supplementation at Different Physiological Stages in Madras Red Sheep

The natural pastures could not support the nutrient needs of the animals in most parts of our country (Chaturvedi et al., 2002). Sheep grazing on such lands are underfed for most part of the year. Hence, the productive and reproductive performances of the animals are low (Chaturvedi et al., 2003). Biomass yield of the community rangeland is low and  livestock stocking density is high in India (Sankhyan et al., 1999). Majority of the sheep farmers in our country (semi arid region) do not supplement concentrate feed even in critical physiological stages (Chaturvedi et al., 2002). It was observed that limited concentrate supplementation in addition to free grazing on community rangeland substantially improved production performance of ewes (Chaturvedi et al., 2003) and growth performance of lambs (Shinde et al., 1995; Chaturvedi et al., 2000; Santra and Karim, 2002). Chaturvedi et al., (2010a) reported that the information on the effect of supplementary feeding on nutrient utilization and production performance of lambs, under field conditions is scanty. Therefore, the present study was undertaken to study the effect of concentrate supplementation on performance of Madras Red breed of sheep at different physiological stages.

The study was conducted at Postgraduate Research Institute in Animal Sciences, during the year 2011 to 2014 at Kattupakkam, Kancheepuram district of Tamil Nadu. In this, sixty ewes were selected in the age group of 3 to 5 years and divided into three groups with twenty in each group. The first group was allowed for grazing for seven hours daily from 9.00 AM to 4.00 PM and served as control group (G1). The second and third group (G2 and G3) of animals were supplemented with concentrate feed @ 10% and 20% of their daily dry matter requirement, respectively such as prior to breeding (14 days), late gestation (last 42 days) and early lactation (first 60 days) and compounded feed for growing lambs up to 120 days of age. The parameters such as body weight changes during different physiological stages, conception rate, birth weight of lambs, fortnightly body weight changes, rumen fermentation pattern and blood parameters were recorded. The collection of rumen liquor (RL) was done at 0 and 4 hours post-feeding at different physiological stages (7^th day after supplementation for prior to breeding, 21^st day after supplementation during late pregnancy, 30^th day after supplementation during early lactation and 120^th day for growing lambs) from the animals using plastic stomach tube and syringe by suction. For estimation of TVFA, about 20 ml of the RL was preserved with two drops of saturated solution of mercuric chloride and for determination of nitrogen fractions about 20 ml of RL was preserved with two drops of 1 N sulphuric acid. The pH of the RL was observed immediately after collection with an electronic digital pH meter. The TVFA content, total nitrogen, non protein nitrogen of the RL were estimated as per the procedure of Barnett and Reid (1956) Kjeldahl method (AOAC) and Pearson and Smith (1943) respectively. TCA precipitable nitrogen (Protein nitrogen) was calculated as the difference between total nitrogen and non protein nitrogen. Blood samples were collected from jugular vein of each animal. The collection of blood was done on 7^th day after supplementation for prior to breeding, 21^st day after supplementation during late pregnancy, 30^th day after supplementation during early lactation and 120^th day for growing lamb. Blood was allowed to clot and centrifuged at 2000 rpm for 10 minutes and the obtained serum was stored at 50^oC in the refrigerator. The blood samples collected from 20 animals in each group at the stage of prior to breeding and for other physiological stages (late pregnancy, early lactation and lambs the samples were collected from 12, 14 and 17 animals for the first, second and third groups, respectively). The blood glucose, triglycerides, cholesterol and BUN were determined by the method of (Tietz,1976) Fossati and Prencipe (1982), Wybenga et al., (1970), Henry (1964) using commercial kits (Biosystems, Chennai) and automatic spectrophotometer respectively. The data were statistically analyzed using one way ANOVA method as per Snedecor and Cochran (1989).

Reproductive performances
 
Out of twenty sheep (Table 1) in each group 16, 18 and 19 were exhibited oestrous symptoms and the percentage of heat observed were 80, 90 and 95 in the G1, G2 and G3, respectively. The numbers of animals conceived were 12, 14 and 17 and the conception percentage was 75, 77 and 89. The concentrate supplemented group showed higher conception rate. The numbers of lambs born were 12, 14 and 17 and the lambing percentages were 75, 78 and 89 for the G1, G2 and G3, respectively. Chaturvedi et al., (2006) also reported that concentrate supplementation at the rate of 1.5% of body weight to ewes during critical stage increased plane of nutrition, conception rate, body condition and birth weight of lambs. The lambing rate of 80.33 to 90.56% in the breeding tract (Balasubramanyam et al., 2011) and 76.83 to 85.56% in farmers flock was reported (Balasubramanyam et al., 2010 and 2012). During early lactation (60 days before and after supplementation) the loss of body weight (kg) in G1 and G2 were 3.9±0.64, 0.76±0.29 whereas the G3 group gained 0.52±0.33 which was statistically significant (P<0.05). The present findings indicate that the ewes in G1 and G2 mobilized their body reserves to meet the additional nutrient requirements of lactation, leading to reduction in their body weight (Idris et al., 2010). Significantly (P<0.05) higher birth weight of lambs were recorded in G2 and G3 (2.77±0.07, 2.83±0.04) than G1 (2.6±0.08). Improvement in birth weight of lambs due to supplementation of concentrate feed during late gestation period have been reported by Shinde et al., (1996); Chaturvedi et al., (2003; 2010a). The birth weight (kg) of lambs recorded by various authors (Sivakumar et al., 2009; Balasubramanyam et al., 2011 and 2012) in Madras Red sheep under field condition ranged from 2.69±0.01 to 2.9±0.01 with mean value of 2.76±0.01.
 

 
Rumen parameters
 
The influence of concentrate feed supplementation was assessed in terms of rumen pH, total VFA produced and nitrogen fractions (Table 2 and 3). The rumen pH was found to be decreasing in G3 group followed by G2 group when compared to G1 group at 4 hours after feeding of concentrate feed in sheep during various physiological stages whereas, the production of VFA was found to be higher in G3 group followed by G2 group when compared to G1 group. Similar observations have been made by Hatfield et al., (1998), Bhatta et al., (2005a) and Askar et al., (2014) in sheep. A reduction in pH and increase in total VFA at 4 h post feeding in G2 and G3 compared to G1 may be attributed to the supply of fermentable carbohydrates through concentrate feed Chaturvedi et al., 2013). The results related to nitrogen metabolism in the rumen of sheep observed during different physiological stages of sheep and growing lambs is presented in Table 2. There were increased levels of total nitrogen, TCA nitrogen and NP nitrogen in sheep at 4 hours after feeding of concentrate feed. The results of this study was in agreement with the observations of Bhatta et al., (2005b) and Singh and Kundu (2010) who also observed improvement in nitrogen metabolism in the rumen due to supplementation of either concentrate or tree leaves. The increase in total N could be correlated to higher concentration of nitrogen supplied in the concentrate feed. Supply of fermentable carbohydrate in the rumen might have improved utilization of ammonia by microbes and ensured better supply of protein and energy for production (Chaturvedi et al., 2003). It is concluded that supplementing concentrate feed in grazing animals for seven hours beneficially influences rumen fermentation pattern.
 

 

 
Blood parameters
 
The results (Table 4) indicated that the higher levels of blood glucose were observed in G3 group followed by G2 group when compared to G1 group. These results were in line with the observation of Mohamed and Abdalla, (2013) who recorded increased blood glucose due to concentrate supplementation. The increased levels of blood glucose observed in this study might be due to production of more propionic acid in concentrate supplemented groups (McDonald, 1996). The triglyceride levels were significantly (P<0.05) high in G3 group followed by G2 group when compared to G1 group. These results were in concordance with the findings of Sarwar et al., (2010) who reported that the triglycerides levels were significantly (P<0.05) higher in concentrate supplemented group than animals fed with fodder only. Significantly (P<0.05) increased cholesterol levels were observed in concentrate supplemented groups (G2 and G3) as compared to un-supplemented group. These results were in agreement with findings of Sarwar et al., (2010) (loc. cit) who reported that the cholesterol levels were significantly (P<0.05) higher in concentrate supplemented group than those fed with fodder only. Muralidharan et al., (2012) also reported that the cholesterol level was significantly (P<0.05) higher in concentrate supplemented group than the group allowed only for grazing. Better plane of nutrition of these groups might have resulted in more cholesterol synthesis in these groups. The level of BUN among various treatment groups was significantly (P<0.05) different. The BUN level was more during breeding and growing age than during pregnancy and lactation. Moreover, the BUN level was more in G3 group followed by G2 group when compared to G1 group. The increased levels of BUN could be due to supply of more nitrogen to these groups. This result is similar to the findings of Sarwar et al., (2010) (loc. cit) who reported that there was linear increase in BUN level when the CP of feed increased. The additional protein apart from grazing supplied through concentrate feed might have increased the BUN values through metabolism. It is concluded that supplementing concentrate feed in critical periods of grazing sheep beneficially changes the serum biochemical parameters. However, the level of BUN observed in this study was higher than the normal level of sheep.
 

It was concluded that supplementation of concentrate feed to sheep @ 20% of dry matter requirement (G3 group) during critical stages of reproduction such as prior to breeding (14 days), late gestation (last 42 days) and early lactation (first 60 days) significantly (p<0.05) improved rumen fermentation pattern, blood parameters and reproduction performance of sheep in terms of body weight gain during late pregnancy and early lactation, conception rate, lambing percentage and birth weight of lambs when compared to concentrate feed supplementation @ 10% of dry matter requirement (G2) or non-supplemented groups.