Growth, onset of puberty of baladi heifers and supsequent milk production as influenced by prepubertal injection of somatotropin
Abstract: This experiment was conducted to evaluate the effect of rbST on average live dialy weight gain, onset of puberty, rcproductive efficicncy of Egyptian native (Baladi) heifers and subsequent milk production. Twenty - Four Baladi heifers (average BW 150 Kg; 9 month of age) were paired; on the basis of weight and age, to either) control (vehicle only) or 2) treatment with recombinanlly derived bST. Subcutaneous injections of rbST were
trated once. every 14-day from 9 month of age until pregnancy was confirmed. All Heifers were fed similar diets, according to their wight throughout the experimental period Heifers were weighed every 2 wk, ,end blood sampel were collected twice weekly after heifers rcached 200 kg. Progesterone concentrations were used to determine onset of puberty heifers were servieed at first estrus after reaching 280 kg of live body weigt To cvaluate impact of trcatment on subsequent milk yield and composition, following parturition. milk yield and composition were recorded and analyzed monthly. Hiefers assigncd to rbST treatment bad an average live daily weight gain of 0.49 compared with 0.45 Kg for control heifers. Number of days from birth to onset of puberty for rbST- treated heirfers was 465 Compared with 473 for control heifers. Treatment with rbst had no effect on subsequent milk yield and composition. These data demonstrate that biweekly injection of rbST in Baladi . heifers at an age of 9 months did not signifieantly affect average daily gain, onest of puberty, reproductive efficiency, and subsequent milk yield of first lactation.
The failure of rbST to significantly enhance productive and reproductive capabilities of Baladi heifers in the present study may indicate that more experiments should be coducted with some modification in the experimental design such as age and weight of heifers imitiate treatment , does of rbst, period of treatment , and/or protein and energy levels in diet.
Key words: Baladi heifers, Puberty, Reproduction, Production, rbst.
Publication year 2005
Pages 239-249
Availability location معهد بحوث الانتاج الحيوانى-شارع نادى الصيد- الدقى - الجيزة
Availability number
Organization Name
serial title Journal Egyptian Veterinary Medical Association
Author(s) from ARC
Agris Categories Animal feedingAnimal physiology - Reproduction
AGROVOC
TERMS		 Heifers. Milk production. Production. Reproduction. Sexual maturity. Weight gain.
Proposed Agrovoc rbst;Baladi heifers;reproductive efficicncy;
Publication Type Journal
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