English abstract
This study was conducted to evaluate the use of the salt tolerant sorghum (Sorghum vulgare, S. bicolor (L.) as a potential tolerant to saline water and efficient water user that may provide a good source of roughage for livestock feeding in Oman. Sorghum variety (Super Dan) planted and irrigated with the three levels of saline water: 3 (S1), 6 (S2) and 9 dsm-(S3). It was manually harvested, dried, chopped and fed to experimental animals. Twenty eight, 3-month-old Omani male lambs with average body weight of 22.2 (+ 1.2) kg were distributed according to body weight (BW) into four groups of seven lambs each. The first group was fed a control diet of Rhodes grass hay (RGH) plus 300 grams of commercial concentrate each. The other groups were given sorghum hay irrigated with three different level of water salinity (3, 6 or 9 ds m') each plus 300 grams commercial concentrate. Daily feed intakes and weekly body weights OS CON Q11 were recorded and the experiment lasted for 9 weeks. A digestibility trial was carried out on 12 animals (three sheep per diet) consisting of 10 days of adaptation and a subsequent 10 days collection period. Blood samples were collected three times at day one, day 33 and day 66 at the end of the experiment and analyzed for haematological and serum biochemistry levels to assess animal health. At the end of the trial the animals were USYE slaughtered and their carcass and meat quality assessed. Chemical analyses indicated that RGH had higher mineral content than sorghum forage grown under various levels of salinity. Animals fed sorghum based diets did not show signs of ill health. The hematological and serum biochemistry were not affected by dietary treatments. There were no differences (P>0.05) between RGH and other treatments in digestibility ices coefficients of acid detergent fibre (ADF), neutral detergent fibre (NDF), and ether extract (EE) between RGH, S1, S2 and S3 diets. However, the Si diet had lower dry
matter (DM), crude protein (CP), Ca, P and gross energy digestibilities but higher ash digestibility. There were no treatment effects on hay, concentrate or total feed intake; total body weight gain or gain per kg/body weight (BW) of experimental animals. The RGH-fed animals had higher S and Zn contents in faeces and a higher S content in meat. Sheep fed the RGH, S1, S2 and S3 diets had average daily body weight gains of 96, 84, 82 and 68 g/d, respectively. There was no diets effect on rumen condition except that ex RGH fed animals had lower N-ammonia and butyric acid concentration. There were no significant differences on body composition, carcass characteristics, meat quality or minerals contents. Transmission electron microscopy investigating on sheep kidneys and livers showed no morphological or pathological changes for animals of different treatments. This study indicated that sorghum forage grown under high salinity levels may be used for feeding Omani sheep without adverse effects on health, performance or carcass and meat quality characteristics. It offers a good use of saline water and soils in mai many parts of the country affected by salinity.
