Global Veterinaria 2 (5): 225-232, 2008 ISSN 1992-6197 © IDOSI Publications, 2008 Corresponding Author: Dr. Amal M. Aboelmaaty, Department of Animal Reproduction and AI, National Research Centre, Dokki, Giza, Egypt E-mail: amalaboelmaaty1@yahoo.com 225 Some Reproductive and Metabolic Responses to Food Restriction and Re-Feeding in Egyptian Native Goats Amal M. Aboelmaaty, M.M. Mansour, Omaima H. Ezzo and A.M. Hamam 1 2 1 1 Department of Animal Reproduction and AI, National Research Centre, Dokki, Giza, Egypt 1 Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt 2 Abstract: This study aimed to evaluate the effect of diet restriction and re-feeding on some reproductive and metabolic aspects. Ten native multiparous non-pregnant goats were equally divided according to their body weight into light (<15 kg) and heavy ( 15 kg) groups. Goats were subjected to 50% diet restriction for 35 days followed by re-feeding for another 35 days. Estrus was synchronized using 60 mg medroxyprogesterone acetate intra-vaginal sponges for 10 days starting on day 4-post re-feeding. Blood samples were collected twice a week with each endorectal ultrasound examination and body weight was recorded every week. Progesterone, insulin like growth factor-1, leptin and nitric oxide concentrations as well as total proteins, albumin, urea, total cholesterol and triglycerides levels were analyzed. In both groups, goats lost their weight during diet restriction and regained it with re-feeding. Ultrasonography revealed that feed restriction persisted corpora lutae in 80% of goats in both groups. One goat in each group (20%) showed signs of estrus and ovulated near the end of the diet restriction period. During the period of re-feeding, all animals in the heavy group and 80% of the light one responded to synchronization and ovulated. During the first estrus after synchronization, heavy group goats showed estrus earlier than the light one. Two out of five (40%) goats had double ovulation and two out of three goats with single ovulation were conceived after mating. All the ovulated light group goats had a single ovulation and one of them conceived after mating. During the 2 estrus after sponge removal, all of the three nd remnant goats of the heavy group had double ovulation and all conceived after mating, but in the light group, three out of the four had a single ovulation, one did not ovulate and only one conceived after mating. Key words: Food restriction Reproduction Metabolites Hormones Goats INTRODUCTION factor-1(IGF-I) and insulin like growth factor binding The adaptation of animals to different levels of metabolites, could also be very useful in predicting and nutrition is a powerful tool that breeders in large areas of avoiding metabolic shortages before any serious or even the world have been exploiting with evident advantages irreparable damage is caused [6]. However, the effect of [1, 2]. Inducing an animal to store reserves (mainly as fat) limited feed resources that can decrease reproductive in periods when fodder availability is high and mobilize efficiency to an extent depends on the degree [7] and those reserves to cope with production needs when reproductive status [8] at the time of feed restriction. affordable feeds are scarce, is a common and economic Ovulation rate was decreased in protein-restricted [8] and strategy [3]. Reproductive performance is commonly fasted ewes [9]; an effect which is pronounced when ewes correlated with body weight changes. Severe body weight were fasted during the luteal phase of the estrous cycle loss is usually accompanied by anestrus [4] suggesting [9]. Moreover, restriction of dietary energy to 0.4 that there is a critical body weight to maintain the estrous maintenance for 13 to 15 days suppressed ovarian cycle in female farm animals. follicular development and resulted in anovulation in Fasting effects on the hypothalamic-pituitary-ovarian 60% of beef heifers [10] and decreased secretion of axis may be modulated by metabolic mediators, including estradiol and LH in milk-fed ovariectomized-prepubertal glucose, insulin, growth hormone (GH), insulin like growth lambs [11,12]. proteins (IGFBP) [5]. So, indicators, such as blood