Muscle fiber type and metabolic profiles of four muscles from the African black ostrich.

Muscle fiber type, fiber cross-sectional area (CSA), enzyme activities (citrate synthase (CS), 3-hydroxyacetyl Co A dehydrogenase (3HAD), lactate dehydrogenase (LDH) and phosphofructokinase (PFK)) and glycogen content were analyzed in the M. iliotibialis cranialis (ITC), M. iliotibialis lateralis, M. gastrocnemius (G) and M. fibularis longus (FL) muscles from 24 ostriches. Type I and II fiber proportions were similar across the 4 muscles, but the ITC had overall the smallest fibers. CS activity was the highest in the ITC, but similar between the remainder of the muscles. 3HAD activities were very low in all muscles, ranging between 1.9 and 2.7 µmol/min/g protein, indicating poor ß-oxidation. The ITC also had the lowest PFK activity. Glycogen content averaged ∼85 mmol/kg dry weight across the muscles with large intramuscular variations. The 4 ostrich muscles present with low fat oxidation capacity and low glycogen content, which could have significant implications on meat quality attributes.

The effect of tree shade on ambient conditions and heat stress indicator traits of new-born South African Mutton Merino and Dormer lambs: Preliminary results.

This preliminary study investigated the provision of shade on heat stress indicators of South African Mutton Merino (SAMM) and Dormer lambs shortly after birth, during the autumn 2017 and 2018 lambing seasons. Newborn lambs were assessed to determine whether welfare, as assessed by respiratory response and rectal temperature as heat stress indicators, survival and early growth benefitted from the provision of shade. Groups consisting of 4-17 pregnant SAMM and Dormer ewes were randomly allocated to 5-10 paddocks with natural shade from trees and 5-9 paddocks that were directly in the sun with no shade available. The lambs were recorded within 24 h of birth at noon. Climate data were obtained from a nearby weather station. The lambs were also weighed at 12 (SD = 2) days of age at tail-docking. Tree shade had a moderating effect on temperature, resulting in lower maximum daytime and higher minimum night-time temperatures. There was an interaction between a temperature-humidity index (THI) and the treatments (access to shade or no access to shade) for respiration and rectal temperature (P < 0.01). Both traits were relatively unaffected by the THI at values below 77. Unshaded lambs exhibited a pronounced upwards trend following a THI-threshold of 77-78. Tailing weight tended to be higher while lamb survival of live-born lambs to tail-docking was lower in lambs born in shaded paddocks but these trends did not persist to weaning. Shade is needed to enhance animal welfare by alleviating the effect of high THI-values on hot days in an autumn lambing season.

The effect of varying dietary nutrient densities on the relative growth of ostrich body components.

The influence of varying dietary protein and energy levels on the relative growth of body components of ostriches was evaluated over a 244-day growth period. One hundred twenty 1-day-old ostrich chicks were randomly assigned to 15 pens. Three varying energy regimes (high, medium and low) and five protein levels (1-5) were supplied ad libitum to each pen. A randomly selected bird from each pen was slaughtered at 1, 35, 63, 103, 159, 168 and 244 days of age. Each bird was weighed, stunned, exsanguinated, defeathered and eviscerated. Individual body components were dissected and weighed at every slaughter age. Proximate analysis was performed on these components, which were ground with the remainder of the carcass, excluding gut content, but including blood and feathers. Based on the analysis of ostrich feathers and the known mass of the feathers, the protein mass contribution of the feathers was deducted from the protein accretion of the bird. All the data were transformed to natural logarithms and regressed against the featherless body protein growth. Intercepts and slopes were compared to determine differences in growth rate ascribed to nutrient densities. Neither dietary energy nor dietary protein level had a significant effect on the relative growth of the measured components in this study. Allometric coefficients were established, which could be helpful to improve the accuracy of simulation modelling attempts for ostrich nutrition.

Feather and skin development of ostriches Struthio camelus.

Information on feather and skin growth is important for the development of mathematical optimisation nutritional models for ostriches. Ostriches (n = 65) were subjected to a four-stage formulated growth diet programme (pre-starter, starter, grower and finisher), with declining protein and energy content. Nine birds were weighed, stunned, exsanguinated, defeathered, skinned and eviscerated at 1, 54, 84, 104, 115, 132 and 287 days of age. Feathers from four pre-selected locations on the body were harvested and weighed. The wet skin weight, wet unstretched skin size and wet unstretched crown size were measured at each slaughter stage. The live weight, feather and skin yields of the birds increased with age at slaughter, as did feather shaft diameter. Prediction models were developed to estimate the yield of the skin in terms of live weight and of empty body protein weight to aid in diet formulation. The allometry of feather growth was determined from total feather weight, as the maturation rates of the feathers differ from that of the ostrich body. Results from this study will aid in setting up a mathematical optimisation nutritional model for ostriches.

The effect of dietary energy content on quality characteristics of Boer goat meat.

The palatability and chemical composition of Longissimus lumborum muscles from 24 Boer goat castrates (eight goats per treatment), finished on diets varying in energy content (9.7, 10.2 and 10.6MJ ME/kg feed), were evaluated by a trained sensory panel on a line scale ranging from low to high intensity for aroma, flavour and texture attributes. Physical measurements as well as proximate analysis were performed for each sample. No differences (P>0.05) were found between the dietary treatments for any of the attributes analysed. Lamb flavour and aroma were the most prominent attributes, while only low levels of goat-like flavours were detected. Juiciness and tenderness had a strong correlation (r=0.864) and were rated to be moderate. The findings suggest that energy density of feedlot diets can be varied to still produce chevon with uniform meat quality characteristics.