A study on certain factors that may affect the production and feed intake of breeding ostriches

[摘要] ENGLISH ABSTRACT: A large amount of research has gone into developing growth models for other monogastric animals, incorporating various biological and animal related factors, feed factors, the environment as well as the interaction between these factors. In order to develop a mathematical optimization model for breeding ostriches, all possible factors that can influence feed intake and production needs to be investigated. Therefore this study was conducted to identify and quantify the possible factors that affect feed intake and production of breeding ostriches.In the first study (Chapter 3), the effect of certain nutrients on feed intake and production of breeding ostriches was evaluated. No specific effect of any one of the tested parameters (additional vitamins, minerals, fatty acids and amino acids) was seen on the production parameters considered. Significant differences were found in the quantity of feed ingested indicating a possibility that breeding ostriches may adjust feed intake to satisfy mineral requirements. The supply of additional vitamins and minerals during the resting period might have an effect on the results.Therefore, the second study (Chapter 4) determined the effect of the addition of minerals and vitamins during the resting and breeding period on the production of breeding ostriches. The presence of a vitamin and mineral premix during the resting period decreased body condition lost by female breeding ostriches with 31.2% and decreased the presence of DIS eggs with 8.1%. The supply of vitamins and minerals in the breeding period decreased the body condition lost by breeding females with 5.3%. Overall it can be concluded that the presence of a vitamin and mineral premix is essential in resting as well as the breeding period.The commonly used protein source in the diet of breeding ostriches, soya oilcake (SOC), has become so expensive that an alternative protein source, cottonseed oilcake (CSOC), was investigated for its possible use in the third study (Chapter 5). Cottonseed oilcake as a protein source had no significant effect on most of the production parameters (total number of eggs, DIS eggs, infertile eggs or chick production), but led to a significant decrease in the quantity of chicks hatched. Until more research results are available, it is suggested that producers follow the precautionary approach and not use CSOC to feed breeding ostriches.With the development of a simulation model for ostriches, the immediate effect of dietary energy content on feed intake as well as its long term effect on breeding ostrich production was determined in the fourth study (Chapter 6). One hundred ostrich breeding pairs were divided into five groups of twenty breeding pairs each for two consecutive breeding seasons and received one of the five experimental diets ad libitum. Although previous studies of Brand et al. (2002, 2003) have indicated that production in the current breeding season can be affected by nutrition of previous breeding seasons, no such effect was seen on the production parameters measured (total egg production, DIS eggs, infertile eggs, chick production, breeding female ostrich weight change or feed intake). Breeding ostriches also showed no indication of regulating feed intake according to the energy content of the feed. Literature revealed that breeding ostrich feed intake may be influenced by the bulk density of the feed. Due to lack of differences in production parameters measured, possible future studies can include the effect of low and high levels of basal energy supplied over three or more consecutive breeding seasons.Egg production is a costly process for female breeding ostriches, requiring high levels of quality feed and often causing loss of body condition. In study five (Chapter 7), the egg laying pattern for breeding ostriches was evaluated. Results from this study indicated that the days until first egg and total days in lay are strongly influenced by the age of the female ostrich. However, due to the egg production of female breeding ostriches being highly variable, and a vast number of factors influencing the production of ostrich eggs, a specific egg laying pattern over the breeding season could not be identified.This thesis makes a significant contribution towards quantifying the factors affecting production and quality parameters in breeding ostriches. Most of the results obtained in these studies can be incorporated into a mathematical optimization model for more accurate predictions concerning feed intake and other production parameters.

[发布机构] Stellenbosch University