Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/23195
Title: The roles of energy- or protein-rich supplements in the subtropics for young cattle consuming basal diets that are low in digestible energy and protein
Contributor(s): Hennessy, D W (author); Williamson, P J (author); Nolan, John (author)orcid ; Kempton, T J (author); Leng, R (author)
Publication Date: 1983
DOI: 10.1017/S0021859600035437
Handle Link: https://hdl.handle.net/1959.11/23195
Abstract: Twenty-seven Hereford weaner steers (mean age 11 months, and live weight 142 17 kg) were used to study the effect of supplementation of an energy-rich grain (sorghum), and/or a protein meal on the liveweight change of cattle on a basal diet of low-quality grass hay over 48 days (Expt 1). The basal hay had an estimated energy value of 6.2 MJ metabolizable energy (ME)/kg dry matter (d.m.) and a nitrogen content of 6.2 g/kg d.m. Corresponding values for the sorghum supplement were 12.4 and 14.4, and for the protein meal 9.6 and 65. The daily rates of supplementation in Expt 1 were (g/head) 0 (nil), 600 (P1) or 1200 (P2) of protein meal pellets or 0 (nil), 560 (S1) or 1120 (S2) of sorghum and all combinations of P1 or P2 with S1 or S2. The carry-over effect of such supplementation on subsequent growth was recorded in Expt 2 when the steers grazed a kikuyu grass pasture for 100 days. In Expt 1, organic-matter intake of hay (HOMI) was increased (P<0.01) by protein but decreased (P<0.01) by the sorghum supplements. By 48 days, P1-supplemented steers were eating 29.5 % more hay than non-supplemented steers, and P2 steers were eating 43.5% more hay than the non-supplemented steers. S1 supplemented steers were eating 29.5% less, and S2 steers 23% less hay than non-supplemented steers. Steers lost weight on the basal hay diet, and at the lower level of sorghum (S1) supplementation, but were able to maintain weight at the higher level (S2) of supplementation. In contrast, steers supplemented with protein gained weight (P<0.01): 430 g/day on P1 and 700 g/day on P2 treatments. None of the steers offered combinations of P and S had liveweight changes as high as those offered only protein supplements. There was no evidence of compensatory gain by the smaller steers in Expt 2 when grazing and unsupplemented. Glucose kinetics in plasma were studied in each steer on day 35 of Expt 1 by means of a single intravenous injection of [2-3H]glucose. The quantity of glucose in the sampled pool and the total rate of glucose entry into the pool (GER) were higher (P<0.01) in steers that were protein supplemented, with GER being related to both ME intake and to N intake per unit ME intake. Urea pool size and entry rate were also estimated on day 35 of Expt 1 using a single intravenous injection of [14C]urea. The quantity of urea in the sampled pool, and entry rate into the pool were increased significantly (P<0.01) by protein, but reduced (P<0.05) by sorghum, supplementation. Rumen ammonia concentrations were low in steers given the hay alone, and when supplemented with sorghum (10-15 mg N/1), but were significantly higher (70 mg N/1; P<0.01) during protein supplementation. It was concluded that growth of cattle on the basal ration was restricted by low voluntary intakes of hay. Intake was increased substantially by protein supplementation. The consequent increase in live weight was due to a greater intake of organic matter which was accompanied by a greater synthesis of glucose and availability of amino acids in the animals. We thank F. Ball, S. Stachiw, J. Cochrane, for skilled technical assistance and C. Perrin for care of the livestock. We are grateful to R. Murison, for statistical advice and to R. Baigent for gas liquid chromatography analysis.
Publication Type: Journal Article
Source of Publication: The Journal of Agricultural Science, 100(3), p. 657-666
Publisher: Cambridge University Press
Place of Publication: United Kingdom
ISSN: 1469-5146
0021-8596
Field of Research (FOR): 070204 Animal Nutrition
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Statistics to Oct 2018: Visitors: 4
Views: 4
Downloads: 0
Appears in Collections:Journal Article

Files in This Item:
2 files
File Description SizeFormat 
Show full item record

SCOPUSTM   
Citations

22
checked on Nov 30, 2018

Page view(s)

110
checked on Dec 29, 2018
Google Media

Google ScholarTM

Check

Altmetric

SCOPUSTM   
Citations

 

WEB OF SCIENCETM
Citations

 

Items in Research UNE are protected by copyright, with all rights reserved, unless otherwise indicated.