Sheep production is the main source of income of farmers living in arid and semiarid regions. Sheep raised in these areas are generally confronted with severe nutritional deficits during food scarcity period which exacerbate disease and health problems and consequently low productive and reproductive performances. These areas are characterized by rainfall seasonality and scarcity resulting in a low fodder potential. During the dry season, forage yields and quality reportedly decline drastically. For both cultivated pastures and natural pastures, forage biomass yields decline drastically in the dry season.
Types of feed for sheep
Cereal and grass fodders: Grass is the world’s most ubiquitous plant. Grass is an incredible survivor at insufficient rainfall areas and is virtually indestructible. Because the roots will regenerate the plant when the tops are eaten, burnt, baked or drowned, grass will survive drought, flood, fire and aggressive cropping. Cereal fodders and grasses are characteristically determinate in growth habit and their herbage quality starts deteriorating after flowering. Cereal fodders like maize, sorghum, pearl millet and oats provide energy-rich herbage to livestock. These have wider adaptability and variability in terms of growth, regeneration potential, yield and quality of herbage.
Legumes: Legumes by and large are indeterminate in growth and thus, maintain quality traits over longer periods. The leguminous fodders have special significance because of high herbage protein and partial independence from soil for their nitrogen needs.
Tree and bushes fodder: Use of tree leaves in animal feeding has been practiced since antiquity. Since crude protein is a major liming nutrient in grasses during the dry season, tree leaves which are known to retain high crude protein content well into the dry season, become an important source for grazing ruminants. Leguminous fodder tree leaves are of particular importance because they normally contain more crude protein than other ligneous species. However, the fodder potential of trees and browses is determined not only by its crude protein content but also by its digestibility, palatability and the associative effects of other. For dry season feeding, drought tolerance of the species, which determines its forage biomass availability during the dry season, is also of importance.
Unconventional herbages: Besides these important groups of fodders, monsoon herbages, weeds and cultivated cactus and azolla like plants, owing to their early bulking capacity, short duration and good nutrition value, are used as supplementary source of feed to the livestock.
Feeding management of sheep
Pre weaning lambs: Lambs after birth should be allowed to suckle their dams within 2-3 hours of birth for better absorption of colostrum. It is rich in immunoglobulin and readily absorbed from intestine with 2-3 hours after birth. The lambs should be kept in an enclosure with their dams during first 3-5 days so that they could suckle colostrum in sufficient quantity. Thereafter the milk should be fed at the rate of 300-400g daily in two feeds. The creep ration should be prepared by mixing maize (40), groundnut cake (30), wheat bran (10), de-oiled rice bran (13), molasses (5), mineral mixture (2) and common salt (1) in parts. Vitamin A, B2 and D3 mixture at the rate of 20g per quintal should also beaded in the creep mixture. Creep mixture rich protein-energy (17-18% DCP and 73-75% TDN) and highly palatable should be started feeding from first 2-3 weeks to suckling lambs beside 300-500g of legume hay and 2-3 hours of grazing on improved pasture. Creep ration should be prepared and supplemented to lambs at the rate of 150-200g daily for achieving desirable growth.
Post weaning lambs: Switching lambs to post-weaning ration depends on both age and body weight of weaned lambs. However, the cost of creep mixture vis-à-vis grower/finisher ration may also have significant bearing in commercial livestock farming. Well fed lambs having genetic potential may have ADG @ 200-250 g. Adequate energy and protein has to be provided in balanced amount for optimum growth of the lambs. Weaned lambs on an average require 32-35 g DCP/ Mcal DE consumed for ADG ranging from 130-160 g. Under field conditions feeding of lambs with concentrate supplementation at 2.5 % of their body weight with routine grazing management seems promising because of reasonable feed cost and better growth. If lambs are grazed on improved pasture and offered grains or concentrate mixture at the rate of 300g during evening hours after grazing. In intensive system lambs are stall-fed on complete ration consisting of concentrate mixture and roughage in 50:50 or 60:40 ratios. They attained 30-33kg body weight at six month of age.
Hogget lambs: Feeding of female hogget is crucial for attaining earlier maturity and body weights for breeding. Hogget are grazed on improved pasture and offered concentrate mixture at the rate of 300 g daily. The supplementation of concentrate mixture should be adjusted depending upon forage supply from grazing land. Hogget should attain body weight of 28-30 kg at 1 year of age. Male hogget should be raised separately for breeding purposes on grazing with concentrate supplementation at the rate of 300 g daily.
Breeding ewes: Reproductive efficiency depends largely upon proper nutrition before and during the breeding season. Large-bodied ewes tend to produce more lambs per ewe. Do not confuse ewes of large size and scale with ewes that look large because they are fat. Usually, excessively fat ewes have lower conception rates and higher embryonic mortality. Furthermore, extremely poor body condition is not conducive to efficient fertility and reproductive performance. Ewes that have not had a properly balanced diet, including adequate phosphorus and vitamin A, may have a poor lamb crop percentage.
Flushing of breeding ewes: Flushing can improve the ewe’s body condition just before and during the breeding season. Generally, the practice is thought to increase ovulation rate. Flushing has more effect early in the breeding season. It is also beneficial late in the season, as it tends to increase the opportunity for all ewes to become pregnant. Provision of extra ration in form of concentrate mixture at the rate of 250-300 g daily 3-4 weeks before the breeding season brings the animals in estrus at a time and also improves the prolificacy and conception rate. The reproduction of animals is triggered by supplementation of concentrate mixture particularly in flocks maintained on low plane of nutrition. In field flocks of dry regions, the pods of legume tree (Khejri, Acacia, Ber) leaves are rich in protein are widely used during the summer months to induce estrus in sheep and goats.
Pregnant sheep: The sheep during last quarter of pregnancy require extra feed for rapid growth of foetus in the womb as well as nourishment of their own body. During early gestation a ewe’s nutrient requirements are only slightly higher than they are for maintenance. Ewes in good condition at the end of the breeding period can loose some weight without hindering normal production. This is particularly true of sheep that have recovered most of their lactational weight loss during the later phases of lactation. If the weight loss is entirely recovered before breeding, lack of gain for the first 60 to 90 days of gestation should not have a negative affect on subsequent production. The last six weeks of gestation is the most critical period in ewe nutrition. Approximately 70 percent of the fetal growth occurs at this time. Nutrient restrictions during this period may result in lighter lambs at birth, increased postnatal lamb losses, lower levels of milk production, and possibly pregnancy disease (ketosis). In late pregnancy, ewes require approximately 50 percent more feed than they do earlier in gestation. If protein is limited during late gestation, lower birth rates and lighter ewe fleece weights can be expected. Ewes in late pregnancy sometimes have difficulty consuming enough feed because of the space occupied by the fetus, particularly when they have twins or triplets. If the ewe is fed a high-roughage ration, she may not be able to consume enough to supply the necessary daily energy requirements. For ewes in late pregnancy consuming high roughage rations, it is generally advisable to feed supplemental grain. A concentrate mixture containing maize (30), groundnut cake (20), wheat bran (20), de-oiled rice bran (23), molasses (5), mineral mixture (1) and common salt (1) parts is prepared. Generally 300g of concentrate mixture is supplemented in addition to grazing for 8-10 hours on improved pasture.
Lactating sheep: Although the milk yield of indigenous sheep is low and ranges between 500-800g daily still this yield is not maintained on grazing alone. Some kind of supplementation either in the form of tree leaves or concentrate mixture should be offered for milk yield. In organized farms, concentrate mixture of 300g daily after grazing is recommended. Physical composition of concentrate mixture for lactating sheep remains similar as that of pregnant sheep.
Breeding rams: Breeding rams should be maintained on grazing on improved pasture and provided 300g of concentrate mixture during breeding season for improving the semen quality and libido. Good quality green fodders like maize, cowpea, oat, doob grass, lucerne, berseem etc. would meet all requirements of breeding rams. The quantity of supplementation should be adjusted as per the availability of forage from grazing lands.
The non-producing (spent) animals are usually above 6 years of age are referred as culled. These animals have crossed their optimum production potential hence they are not cared by the farmers which ultimately leads to loss of body condition score. Among different feeding strategies, challenge feeding programme involving high energy diet helps the animals to show recuperative changes in intake, metabolism and improvement in body condition. Short-term feeding of starch based diet improved the body condition of cull ewes. Improvement in body condition and carcass characteristics were also recorded in cull ewes fed high energy diet at 2.5% of bodyweight for a period of 90 days. Furthermore, feeding of compound feed blocks with urea as a cheaper nitrogen source and rumen protected fat improved performance, nutrient utilization and enhanced carcass traits for better marketability and returns from cull ewes. Therefore, a short duration (45-90 d) feeding strategy with minimum feed input and maximum output (live weight gain) may fetch a higher price for the animals, which will compensate the feed and rearing cost and cancel out the recurring expenditure on these animals.