Determination of the nutrient requirements of breeding ostriches

[摘要] ENGLISH ABSTRACT: The nutrient requirements for breeding ostriches are currently not well-defined. Quantification of the nutrientrequirements will improve the financial wellbeing of the industry. A study of the growth of the reproductive organsand liver, together with various production studies, were therefore undertaken in order to gain knowledge aboutthe nutrition of breeding ostriches, thereby quantifying the nutrient requirements of breeding ostriches.Various studies were conducted to determine the influence of dietary protein, amino acids and energy onproduction levels of breeding ostriches.In a first study, five diets, varying in crude protein (CP) but with a constant energy content of 9.2 MJ ME/kg feed,were provided at a feed intake level of 2.5 kg/bird/day. The dietary CP levels were 7.5%, 9.1%, 10.8%, 12.3%and 14.0%. No differences (P>0.05) between treatments (total eggs per female per season) were found fornumber of unfertilized eggs (eggs per female per season; 8.9±0.8), dead-in-shell chicks (8.0±0.5), number ofchicks hatched (19.1±1.1) and change in mass of females (-16.2±1.6kg). A tendency was observed for adifference in total egg production (mean and standard error; 39.1±3.6; P=0.08). The 12.3% CP diet caused thelowest (P<0.05) change in live mass (-3.8±2kg) for male birds. No interaction (P>0.05) occurred between thegenotype of the bird and the dietary protein concentration for both egg and chick production.In a second study, six diets varying in ME (MJ ME/kg feed), were provided at an average feed intake level of 3.4kg/bird/day. The levels were 7.5, 8.0, 8.5, 9.0, 9.5 and 10.0 MJ ME/kg feed respectively. No differences (P>0.05)were observed for total eggs produced per female per season (44.8±7.8), number of chicks hatched (15.4±4.1), number of infertile eggs (11.5±3.8), number of dead-in-shell eggs (12.1±3.2) and change in mass of females(10.7±3.6kg). Males increased linearly (y=2.4x + 2.45; R2=0.09; P<0.05) in live mass as the dietary energycontent increased. Two eggs per diet per month were analyzed for crude protein, crude fat and trace elements,and one egg per diet per month was analyzed for fatty acid composition. Eggs from the first and last month ofthe season were subjected to amino acid analysis. Analysis of variance showed no difference in crude proteinand fat (P>0.05) content of eggs between the experimental diets, as well as for the calcium content of eggshells.The proline content differed (P<0.05) between the diets. The C18:3n-3 (linoleic acid) content of the eggsincreased (P<0.05) amongst the dietary treatments. Crude protein, fat and C18:3n-3 content in eggs increased(P<0.05) for the number of the egg in the laying cycle.In a third study, the feed intake of breeding ostriches, as affected by dietary energy content was investigated.Average feed intake (kg feed/bird/day) was not affected (P>0.05) at any dietary energy level when levels of 8.0,8.7, 9.4, 10.1, 10.8 and 11.5 MJ ME/kg feed were provided. The mean and standard error was 3.7±0.2kg.The production of breeding female ostriches was not influenced by dietary ME and protein at these feed intakelevels. Ostrich birds do not have the ability to regulate their feed intake at any dietary energy level as used in thisstudy. The amount of nutrients deposited in the eggs had no influence on the reproductive efficiency of thebreeding female ostrich. The experiments also revealed that female breeding ostriches were independent ofdietary energy and protein as used in this study for the mean frequency of egg laying at various dietary proteinand energy levels (P>0.05).In a fourth study, the growth and development of the reproductive organs of female birds at the onset of thebreeding season were investigated. The amount of nutrients needs to be determined in order to support thegrowth of the reproductive organs during the breeding season, due to the fact that these organs are linked toegg production. It was thus necessary to investigate whether the reproductive organs grew and developedduring a season. The first slaughter interval was conducted at the start of the breeding season. The ovary,oviduct and liver were collected, weighed after each slaughter and analyzed. Ovary and oviduct were analyzedfor crude protein and fat. No differences (P>0.05) were observed between the different slaughter intervals for themass, crude protein and fat content of both organs. No trend (P>0.05) in the weight of the oviduct could beobserved over the 49-day period, this weight being highly correlated with body weight; whereas the ovary weighttended to be correlated with the time after the onset of the breeding period, although the variation in weights,both within and between weighings, was very high. The variation in the weight of the ovary probably reflectsdifferences in the laying pattern of individuals. The number of follicles were not affected (P>0.05) by the numberof days after mating. Livers were assessed for crude protein and fat, but no difference (P>0.05) was detectedbetween the intervals, but the weight difference amongst the slaughter intervals was significant (P<0.05),suggesting that the ostriches used liver reserves to supplement nutrients that obtained from the diet for thedevelopment of the reproductive organs. This data will be used in an optimising model (Brand & Gous, 2006) to predict the nutrient requirements of female breeding ostriches. This study suggests that the female breedingostrich might need additional protein during the first 7 weeks of the breeding season.Results from Chapter 4 and previous studies were used to calculate the energy, protein and amino acidrequirements for the egg production and maintenance of the breeding female ostrich. Two methods were used todetermine the energy requirement for egg production. The Metabolisable Energy requirement for egg production(MEe) and efficiency of ME utilization for energy deposition in the egg (ko) was calculated as 12.2 MJ (for anaverage size egg of 1.4kg) and 0.8 respectively. The Effective Energy requirement for egg production (EEe) andmaintenance (EEm) was calculated as 15.9 MJ/day and 17.1 MJ/day respectively. Average total daily proteinrequirement (TPt) was calculated as 175g day. The amino acid requirements for maintenance and eggproduction is also provided, which is lower than previous studies. This study also provides evidence that the nutrient requirements are different for every month of the breeding season.

[发布机构] Stellenbosch University