Title page for ETD etd-09012011-144756


Document Type Master's Dissertation
Author Steyn, Willem Johannes
Email willem.steyn@topigs.com
URN etd-09012011-144756
Document Title Effects of ad libitum and restricted diets in different feeding regimes on growth and carcass attributes of boars of a selected genetic line
Degree MSc(Agric)
Department Animal and Wildlife Sciences
Supervisor
Advisor Name Title
Dr C Jansen van Rensburg Co-Supervisor
Prof N H Casey Supervisor
Keywords
  • finisher pigs
  • diets
  • ad libitum
Date 2011-04-14
Availability unrestricted
Abstract
The current modern commercial pig is an animal that has evolved through deliberate breeding programs, controlled environmental influences and nutrition to yield a highly efficient feed converter and fertile animal. The objective of this study was to measure the growth performances and carcass characteristics of entire male grower – finisher pigs which were subjected to different seasonal variations, nutrient dense diets, feeding regimes and group situations under South African circumstances. Period 1 was conducted in the winter from 6 June 2008 to 13 August 2008 and Period 2 in the summer from 3 October 2008 to 10 December 2008. The sire lines that were selected for the experiment had the same genetic breeding values (Topigs Selection Index value), of which two sire lines were the same in both Period 1 and Period 2 and one of two different sires lines was used either in Period 1 or Period 2. The animals were fed two different rations, a high (FH) and a low ration (FL), with the low ration’s specifications being 95 % of the high ration. The animals were randomly allocated three different feed regimes throughout the trial; restricted single feeding (RSF), ad libitum single feeding (ASF) and ad libitum group feeding (AGF). In the winter animals had a greater growth response compared to the summer, with end weight and average daily gain being significant (P<0.05) higher. A significant (P<0.05) improvement in average daily gain, feed efficiency and protein deposition rate were observed when animals were fed a higher energy and protein content in their diet, especially during summer. A significant (P<0.05) improved feed conversion was observed for restricted animals, but end weight, average daily gain and average protein deposition rates were significant (P<0.05) lower compared to ad libitum group and individually fed animals. In conclusion; the impact of decreasing the nutrient density of the diet for growing pigs through incremental changes in diet composition had a variable impact on overall growth performance and carcass quality. Feeding the high energy and protein ration improved growth performance during summer, but also in the initial stages of growth when feed intake capacity was limited. The objective when formulating diets should be to provide the essential amino acids and energy in amounts needed to support maximal and efficient growth. Using growth models estimated optimal feed intake curves will not deliver optimal results. Only when measuring and calculating the actual feed intake and protein deposition rates optimal performance levels will be reached. Measurements of feed intake and growth performance data derived from pigs penned individually should be adjusted before they can be applied to commercial situations or research conditions in which pigs are penned in groups.

© 2010, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Steyn, WJ 2010, Effects of ad libitum and restricted diets in different feeding regimes on growth and carcass attributes of boars of a selected genetic line, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-09012011-144756 / >

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