Effect of growth prompting on productive and reproducdtive perfoemance of heifers

Abstract: The objective of this experiment was to evaluate the effects of altered forage: concentrate ratio and DL-methionine analog supplementation on growth performance of growing heifers until confirmed pregnant. Twenty-four Holstein heifers with an average of age 5.6 ± 0.36 mo and weight 116 ± 6 kg, were fed restricted intakes formulated to allow for 800 g/d (NRC, 1989). Experimental diets were formulated to contain either 50: 50 (low forage) of 75: 25 (high forage) forage: concentrate ratio diets (DM basis). Forage comprised of com silage and constant amounts of berseem hay (1.5 and 2 kg/ h/ d for low and high forage, respectively). Treatments were fed with or without methionine hydroxy analog supplementation (MHA, 2.] g /day/ 100 kg BW). Live body weight was taken biweekly, while some body measurements and blood samples were taken monthly. Blood plasma was taken twice weekly after insemination to determine the plasma progesterone concentration. Digestibility trial was performed at 370 kg BW, during the digestibility trial heifers were fed individually in tie-stall. Actual intakes of nutrients were lower than expected intakes due to lower com silage DM ratio. DM, OM, CP, and NFE digestibility were significantly (P < 0.05) improved by reducing the forage portion of the diet, hoverer CF digestibility had a significant (P < 0.05) opposite direction. While, supplementation of MHA resulted in trends toward increased DM digestibility. Ruminal TVF A were significantly higher in low forage groups, however, ruminal PH was higher in low forage groups,while MHA trend to decreased TYF A only.lnsignificant differences were observed for plasma total protein triglyceride, creatinine, urea, in addition to negligible difference for albumin, globulin, and A/G ratio, while significant (P < 0.05) decreasing in plasma cholesterol was recorded for low forage without MHA treatment, also high forage without MHA group showed a trend to decreased plasma urea. Throughout the feeding period, ADG was not affected across all treatment rations (0.681 LF, 0.685HF, 0.695 LFM, and 0.663 HFM, SE± 0.033 kg/d). Gain of heifers body weight and measurements were not different among treatments. However, low forage groups had better feed¬ conversion for DM, ME and TDN, while CP and DCP conversion were better in high forage groups. Age at 330 kg BW was recorded an average of 15.98 mo (15.85 LF, 16.26 HF, 15.41 LFM, and 16.38 HFM, SE± 0.53 mo), as well as BW at age 14 mo and age and BW at AI, or conception not affected by treatments. Total and daily feed cost for high forage groups was significantly (P < 0.05) better than low forage groups, but total and gain feed cost from 150 to 330 kg BW did not affect by treatment may be due to the deep gap within treatments, especially in high forage groups. Thus, we can feed growing heifers in
this tested forage strategy under quality recommended for feedstuffs, and used satisfactory method for feeding. Notwithstanding, MHA addition did not has effect on growing heifers performance, nevertheless MHA addition may has influences on DM digest and blood metabolism, and may be the amount used under this experimental was not enough to improve growth performance.
Keywords: growing heifers, forage: concentrate ratio, DL¬methionine, forage strategy, nutrients digestibility, rumen parameters, blood plasma parameters, growth and reproductive performance, plasma progesterone.
Publication year 2011
Pages PP. 136
Availability location مكتبة معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
Availability number 1161
Organization Name
Country Egypt
Author(s) from ARC
Agris Categories Animal physiology - NutritionAnimal physiology - Reproduction
Blood plasma. Growth. Progesterone. Reproductive performance.
Proposed Agrovoc blood plasma parameters;rumen parameters;nutrients digestibility;forage strategy;DL¬methionine;growing heifers;forage: concentrate ratio;
Publication Type Master Thesis