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The effects of different dietary energy concentrations on ostrich production variables were examined in two separate trials. The first trial tracked changes in production variables from the pre-starter phase through the starter phase and grower phase. The second trial was based on the finisher phase per se. In both trials, the influence of dietary energy on feed intake, feed conversion ratio (FCR) and growth variables was investigated. Additionally, basic abattoir weights were recorded, and measurements of the feathers and skin were performed. In both trials, three diets with different concentrations of dietary energy were given during each phase where the low-, medium- and high-energy concentrations for each phase were as follows: 13.5, 14.5 and 15.5 MJ ME/kg feed pre-starter; 12.5, 13.5 and 14.5 MJ ME/kg feed starter; 10.5, 11.5 and 12.5 MJ ME/kg feed grower and 9.5, 10.5 and 11.5 MJ ME/kg feed finisher. Feed and water were available ad libitum in both trials. Overall, it was found that the best performance for growth, FCR, skin size and grade, live weight, carcass weight and thigh weight were obtained on the medium-energy diet during the pre-starter, starter and grower phases. During the finisher phase, improved growth rate and tanned skin size was found in birds given the diet with the highest energy concentration (11.5 MJ ME/kg feed). Carcass weight, growth rate and certain feather variables were also significantly influenced by gender.

The value of feed protein sources in ruminant nutrition is measured by how effectively the protein is degraded in the rumen and converted into microbial protein. High-producing ruminants acquire high nutritional requirements to sustain their metabolic demands for production and performance. However, protein sources occasionally fall short in supplying the required amount of rumen undegradable protein and amino acids. Chemical treatment (formaldehyde) could be used to increase the efficiency of protein sources, which are highly degradable in the rumen. Canola oilcake meal (CM) and sweet lupin seed (SL) were treated with formaldehyde (40% w/v) at concentrations of 10 g/kg (F10) and 15 g/kg CP (F15). In this study, six Dohne Merino wethers fitted with rumen cannulas were used to determine the effect of formaldehyde treatment on the in situ dry matter and crude protein digestibility. The treatments entailed CM control (CMF0), CM treated with 10 g/kg CP formaldehyde (CMF10), CM treated with 15 g/kg CP formaldehyde (CMF15), SL control (SLF0) SL treated with 10 g/kg CP formaldehyde (SLF10) and SL treated with 15 g/kg CP formaldehyde (SLF15). Treatments were incubated in the rumen at time intervals of 0, 2, 4, 12, 36, 48, 72, and 96 hours. Overall, formaldehyde treatment significantly decreased rumen degradation at all outflow rates of both CM and SL. Therefore, formaldehyde treatment could be used to increase the rumen undegradable protein fraction. Potential improvement in animal performance in terms of live weight gain, average daily gain, and feed conversion efficiency has to be evaluated in production studies. [ABSTRACT FROM AUTHOR]

Earlier studies on breeding birds indicated no effect of dietary energy-content on feed intake. This observation is contradictory to results for other animals and/or poultry where feed intake decreases with an increase in dietary energy level. Literature revealed that a lack of certain nutrients may cause animals to consume more feed than necessary to satisfy their nutrient requirements for these limiting nutrients. In this study eight diet groups were evaluated. A standard commercial diet plus one of the following supplements: (i) Standard diet without a vitamin and mineral premix pack (control diet), (ii) with a normal premix pack, (iii) with normal vitamin and 2 x trace elements (M x 2), (iv) with normal trace elements and 2 x vitamins, (v) with a normal premix pack and limestone added as calcium source; (vi) with a normal premix pack and monocalcium phosphate added as phosphorus source, (vii) with a normal premix pack and soybean oilcake added as crude protein source, (viii) with a normal premix pack and linseed added as a fatty acid source. Significant differences were recorded in the quantity of feed ingested by birds between the diet with surplus minerals (M x 2) (Group 3) (2.3 ± 0.3 kg/bird/day), the diet with no vitamins and minerals added (Group 1) (2.7 ± 0.3 kg/bird/day) and the diet with added fatty acids in the form of linseed (Group 5) (2.9 ± 0.5 kg/bird/day). This indicates the possibility that ostriches may adjust feed intake to satisfy their mineral requirements. No statistically significant relationship was found between the thickness and strength of the shell. Significant differences in shell strength (mean value of 154.7, 109.9, 140.4, 142.7, 153.0, 143.4, 138.4 and 151.1 N/cm², respectively) were found between all treatments, but no specific pattern could be identified. Results further revealed no effect of dietary treatment on egg production, dead-in-shell eggs (DIS), infertile eggs or chick production. Further experiments that include certain dietary treatments during the five months rest period are currently being done to quantify the effect of the addition of minerals and vitamins during this period on the production of breeding ostriches. [ABSTRACT FROM AUTHOR]

ß-adrenergic agonists are commonly used in livestock production to enhance meat production and decrease the fat content of the body. ß-adrenergic agonists normally improve growth performance. Recent increases in meat prices and the change in consumer preference towards leaner meat have resulted in more lamb producers opting to finish leaner mutton/lamb on farms in a feedlot system. The aim of this trial was to determine the effect of dietary energy, as well as the inclusion of a ß-antagonist, on the meat quality of feedlot lambs. South African Mutton Merino lambs (108) of different sexes (rams and ewes) were weaned at 120 days of age and were randomly divided into six groups (18 lambs per group). The treatment consisted of three different dietary energy levels (high 12.7 MJ ME/kg feed, medium 12.0 MJ ME/kg feed and low 11.3 MJ ME/kg feed) with either the inclusion of a ß-adrenergic agonist (zilpaterol hydrochloride) at 8.4 g/ton or not. Data were analysed according to a 3 (dietary energy) x 2 (inclusion of a stimulant) x 2 (sex) factorial analysis. No interaction occurred between treatments and the data were presented as the effect of dietary energy level, the inclusion of a stimulant and sex on proximate components, fat thickness and the tenderness of the meat. The factors ß-adrenergic agonists and dietary energy level had no effect on the proximate components, fat thickness or the tenderness of the meat. The ewe lambs' 9-11th rib-cut had a significantly higher fat content than the ram lambs (27.9% vs. 23.1%, respectively). Meat from ram lambs was less tender (63.60N) compared to that from ewe lambs (57.82N). Neither the inclusion of the ß-adrenergic agonist (59.8N vs. 61.9N) nor the dietary energy level (59.3N vs. 63.5N vs. 59.3N) had an effect on the tenderness of meat from lambs in this study. [ABSTRACT FROM AUTHOR]

Recent increases in mutton lamb prices have resulted in many lamb producers opting to finish more and more lambs on the farms in a feedlot system rather than marketing directly from the field. The aim of this trial was to determine the effect of dietary energy, as well as the inclusion of a ß-adrenergic agonist, on the production of feedlot lambs. South African Mutton Merino lambs (108) of different sexes were weaned (± 36.4 kg) at ca. 120 days of age and were randomly divided into six experimental groups (18 lambs per group), which were adapted to each treatment. Lambs were housed in individual pens. The treatments consisted of three diets (diet 1: 11.3 MJ ME/kg food, diet: 2 12.0 MJ ME/kg food and diet 3: 12.7 MJ ME/kg) with either the inclusion or absence of a ß-adrenergic agonist at 8.5 g/ton. The experimental design was a 3 x 2 x 2 factorial design with dietary energy level, the provision of a ß-adrenergic agonist and sex as main factors. No interaction occurred between treatments and data are presented as the effect of dietary energy level and the inclusion of a stimulant on the intake, growth and feed conversion ratio (FCR). Neither the dietary energy content nor the ß-adrenergic agonist had an effect on FCR. Neither one of the main factors had a significant effect on feed intake. The sex of the lambs had a significant effect on the average daily gain of the lambs with the ewes growing faster than the rams. [ABSTRACT FROM AUTHOR]

A study was conducted to describe the changes occurring in body composition of ostriches over a 285-day growth period. Fifty two birds were given a choice of four diets with different protein (180 and 120 g/kg feed) and energy (8.5 and 13.5 MJ ME/kg feed) levels, on the assumption that the birds would select from the four feeds according to their protein and energy requirements, and thereby grow close to their potential without being constrained by the quality of feed supplied to them. Birds were weighed at approximately 10-day intervals and randomly selected birds were slaughtered at 1, 54, 120, 162 and 285 days of age respectively. Proximate analyses were done on the complete empty carcasses and the components were expressed as a percentage of live weight at the different slaughter ages. The Gompertz growth curve was fitted to the live weights of the birds and to the weights of the individual chemical components. The change in body weight with age as the only independent variable can be considered as a good (R² = 0.93) description of growth in ostriches. The growth parameters a, b and c were estimated as 119.4, 0.009 and 156.3 respectively. Body protein and moisture concentrations decreased as the birds aged, while the body ash concentration remained relatively constant and body fat concentration increased. Fitted Gompertz parameters for the different chemical components were, for fat; a = 33.6, b = 0.013 and c = 143.4 (R² = 0.914), protein; a = 44.5, b = 0.015 and c = 113.9 (R² = 0.961), ash; a = 10.3, b = 0.016 and c = 118.2 (R² = 0.965), and moisture; a = 55.0, b = 0.014 and c = 116.9 (R² = 0.965). Similar to other animals, fat was a late maturing tissue and protein a relatively early maturing tissue. These results are important in describing the growing ostrich and this information can be used to model the nutrient requirements of these birds. [ABSTRACT FROM AUTHOR]