تاثير جايگزيني سطوح مختلف كاه گندم با برگ خرما بر عملكرد و سلامتي بره‌هاي بلوچي

The effect of wheat straw substitution by different levels of date palm leaves on performance and health of Baluchi ewe lamb

هدف از این مطالعه، ارزیابی تاثیر تغذیه جیره¬های حاوی برگ خرما بر رشد و عملكرد بره¬های بلوچی بود. تعداد 24 رأس بره ماده بلوچی با میانگین سنی 4 تا 5 ماه و وزنی 9/3 ± 48/20 كیلو گرم، با یك جیره كل مخلوط شامل 39 درصد علوفه و 61 درصد كنسانتره تغذیه شدند. بخش علوفه‏ای جیره‏های آزمایشی شامل 1)كاه گندم 24 %، 2) كاه گندم 16% و برگ خرما 8%، 3) كاه گندم 8% و برگ خرما 16% و 4) برگ خرما 24 % بود. تمامی بره‌ها با یك كنسانتره یكسان تغذیه شدند. میانگین مصرف خوراك روزانه بره¬های تغذیه شده با جیره¬های مختلف به¬ترتیب 856، 917، 983 و 1033 گرم در روز برای جیره 1 تا 4 بود. اختلاف بین میانگین مصرف خوراك روزانه در جیره¬های مختلف معنی¬داربود (05/0P <). میانگین افزایش وزن روزانه بره‏های تغذیه شده با جیره 1 تا 4 به ترتیب 106، 143، 156 و 165 گرم بود. بهترین ضریب تبدیل غذایی در بره¬های تغذیه شده با جیره‏ حاوی 24% برگ خرما مشاهده شد (38/6 كیلوگرم خوراك برای هركیلوگرم اضافه وزن). ازت آمونیاكی و pH شكمبه¬، نیتروژن اوره¬ای و گلوكز خون در محدوده نرمال برای این نوع از دام‌ها بود. نتایج این آزمایش نشان داد كه جایگزینی كاه گندم با برگ خرما بدون بروز اثر سوء ضمن تغذیه دامها با هزینه كمتر در مناطق گرم و خشك مركز و جنوب ایران می تواند با بازده مناسب همراه باشد.

Introduction A major constraint of animal production in south of Iran is the lack of cheap source of roughages. Date palm leaves (DPL) is one of the most abundant agricultural by-products in south of Iran. Almost all pruned leaves are discarded in the fields, mainly for nutrients recycling and soil conservation (M. Wan Zahari, et al1999). The yearly maintenance of date palm tree produces a (around 20 kg per each tree) considerable quantities of green leaves (Bahman et al (1997); Pascual et al (2000)). Ruminant can utilize crop residues, with poor nutritional value. These residues are traditionally fed to animal as the main part of diet in many developing countries. However; dry matter intake of these by-products are not adequate to fulfill the nutrient requirements of livestock even at maintenance level (Dixon and Egan, 2002). DPL has a great potential for use as a roughage or bulk source in total mixed ration (TMR) for ruminants in dry areas. Detailed studies on fermentation characteristics and palatability of DPL silage, as well as on animal performance, have been reported by many workers (e.g. Abu Hassan and Ishida, 1991; Ishida and Abu Hassan, 1997; Oshio et al., 1999). Some researchers such as El-din and Tag-El-Din, 1996; and Bahman et al., 1997 have reported that DPL cannot be fed to animals because of low crude protein (6-7%) and high level of fibrous cell wall content low palatability and digestibility. Therefore we design one experiment that investigates possibility of using DPL without any enrichment. The objective of this trial was to study the effect of replacement DPL with wheat straw and voluntary intake, average body gain and health of Baluchi ewe lambs. Materials and Methods Twenty-four Iranian Baluchi female lambs with initial body weight (BW) of 20.48±0.5 kg and age of 130±10 days were assigned to 4 dietary treatments in a completely randomized design. Groups were balanced for weight and experimental trail lasted for 76 days. All lambs were given a TMR composed of 39% forage (alfalfa and wheat straw or DPL) and 61% concentrate. The concentrate portion (61%) was the same for all treatments, therefore the dietary treatments differed only in forage part of diet(39%) and they were 1) wheat straw (24%), 2) wheat straw (16%), DPL (8%), 3) wheat straw (8%), DPL (16%), 4) DPL (24%). The diets were fed in form of ad libitum and total mixed ration (TMR). DPL were collected in fall season (time of pruning), dried under the sun light and stored and a dry clean shed up to starting the feeding trial. DPL were chopped in particle size of 3-5cm before mixing. Approximately all diets were isocaloric and isonitrogenos. Diets were offered to the lambs twice daily in almost equal meals at 8 am and 4 pm to meet their feed requirement and fresh water was also available for sheep at all times during the trail. Results and Discussion Feeding of DPL to Baluchi sheep did not affect their health. Such results have been reported elsewhere by other workers (Osman Mahgoub, et al., 2005). Lambs fed by diet 4 had higher fibrinogen content in their blood samples than other animals in other treatments. The highest feed intake (1033 g/day) was observed in diet 4 containing 24% of DPL. In contrast the animal fed by diet 1 (24% wheat straw) had the lowest feed intake (856 g/day) among all treatments. Average body weight gain of lambs fed by diet 1 was significantly (P <0.05) lower than other groups. The best feed conversion ratio was recorded for the lambs on diet containing 24% DPL (6.38 kg feed intake for each kg of weight gain). Lower BW gain of animals fed by non-conventional feed is well documented mainly because of higher lignifications. Kafilzadeh et al (2009) reported that low digestibility of DPL than wheat stubble could be due to lesser accessibility of ruminal microbes to the fiberus cell wall of DPL. ConclusionThis study indicates that Baluchi lambs can be fed with a diet based on date palm leaves and improve performance in tropical areas where lack of feedstuff source is the first limitation for livestock industry. Feeding of DPL requieres further investigation and research about anti nutritional factor but in this study observed that feeding of DPL to lambs at 24% is possible without any negative effect and it is a good result for this agricultural by-product.