Effects of non-steroidal growth implant and dietary zilpaterol hydrochloride on growth and carcass characteristics of feedlot lambs

The effects of steroidal growth implants alone or in combination with β-adrenergic agonist feed additives have not been studied thoroughly in mutton sheep in South African feedlot conditions. This study investigated the effects of a non-steroidal growth implant zeranol (Ralgro®), alone or in combination with zilpaterol hydrochloride (Zilmax®), on growth performance, carcass characteristics, and selected meat quality traits in 160 SA Mutton Merino ram lambs fed in a commercial feedlot. The experimental design consisted of two Ralgro treatment groups x two Zilmax treatments x two Zilmax feeding periods x 20 animals per treatment group. Lambs were randomly allocated to eight treatment groups, of which one half were implanted with Ralgro after arrival, followed by feed supplementation with Zilmax at two Zilmax feeding periods during the finisher phase, compared with negative control treatments (e.g. no Ralgro or Zilmax; Ralgro + no Zilmax; or no Ralgro + Zilmax). All lambs were fed the grower ration traditionally used by the commercial feedlot, which contained 16.89% crude protein (CP) and 2.94 Mcal/kg dry matter (DM). Zilmax was supplemented in the feed at 40 mg per animal per day and fed for 18 days or 25 days, plus three days withdrawal. Lambs that did not receive the Zilmax treatment were fed the basal diet without Zilmax feed supplementation. Ralgro significantly increased average daily gains (ADG) and cold carcass mass (CCM) of lambs. Lambs supplemented with Zilmax during the finisher phase had higher ADG, greater CCM and increased dressing percentage by ca.1.1% compared with those in the control group. Lambs fed Zilmax for 25 days had higher CCM than those fed for 18 days. The duration of the Zilmax treatment also decreased hide weight, fat thickness and shear force values (tenderness). Zilmax increased ADG and CCM in lambs, particularly if combined with Ralgro implants during the growing phase. The results from this study indicate that the combination of Ralgro implants with Zilmax feed supplementation during the finisher phase had additive effects and increased ADG and CCM of feedlot lambs.Keywords: Growth performance, meat quality, South African Mutton Merino, sheep, Ralgro®, Zilmax

Carcass characteristics of South African native chicken lines

Carcass characteristics of the Koekoek, New Hampshire, Naked-Neck, Lebowa-Venda and Ovambo chicken lines were evaluated. The highest dressed-carcass mass was recorded for Ovambo chickens and the highest percentage breast muscle was recorded for Naked-Neck chickens. Percentage fat and fatty acid composition differed between lines (p < 0.05). Carcass mass and fat content of the native chicken lines were less than in a commercial broiler line. It was concluded that the Ovambo and New Hampshire chicken lines appear to have the most suitable carcass characteristics for low-input systems where poultry production is aimed at household food security. (South African Journal of Animal Science: 2000, 30(1): 53-56

Effects of electrical stimulation and age at slaughter on carcass and meat quality of two Sudanese Baggara beef types

This study aimed to evaluate the influences of electrical stimulation (ES), age at slaughter, and breed type on muscle pH, the decline in carcass temperature, and meat quality attributes of Sudanese indigenous Baggara cattle. Eighty Baggara bulls, representative of Nyalawi (n = 40) and Mesairi (n = 40) breed types, were selected at their typical marketing age of about 4.5 years. Electrical stimulation was applied for 30 seconds at 20 minutes post mortem to 20 randomly selected carcasses from each breed type and compared with 20 carcasses from each type that were not electrically stimulated (NES). Samples of the Longissimus dorsi muscle were collected for meat analyses. Breed type showed no significant influence on meat quality characteristics, while ES and age at slaughter did. Electrical stimulation accelerated the carcass pH decline significantly up to 24 hours post mortem. Meat from electrically stimulated carcasses and younger animals resulted in higher L* values, lower a* values, higher hue values, and better tenderness. Older Mesairi animals had darker meat than their younger counterparts. Electrical stimulation reduced water-holding capacity (WHC), although it had no influence on cooking loss (CL). Meat from older cattle showed better WHC compared with meat from younger animals. The ES treatment decreased the variations in meat tenderness between the younger and older bulls. It is concluded that the use of ES and younger bulls produced more tender meat with better colour. Therefore, these practices should be adopted in Sudan to ensure better beef quality management.Keywords: Longissimus dorsi muscle, meat characteristics, Mesairi, Nyalawi, Suda

Possible use of BHT to estimate carcass fat content in small ruminants

(South African J of Animal Science, 2000, 30, Supplement 1: 149-150

Effects of non-genetic factors on the inter-calving period of Nguni cows in South Africa

The purpose of this study was to evaluate the effect of geographical  regions of South Africa on the inter-calving period of Nguni cows. Data of Nguni cows (n = 26 681) from 427 Nguni breeders in the Savannah and the Grassland Biomes were statistically analyzed to establish the impact of non-genetic factors on the inter-calving period (ICP) of these cows. Cows with an ICP of less than 315 and above 730 days were removed from the dataset before analysis, to comply with Nguni breed standards. Dam age was included as a covariant. The ICP increased slightly up to 48 months of age, after which a decline was noticed up to the age of 108 months. Cows in the Savannah Biome had a shorter ICP than those studied in the Grassland Biome. Within the Savannah Biome, the ICP of cows was significantly shorter in the Eastern Kalahari Bushveld bioregion than in any other bioregion, while in the Grassland Biome the ICP was significantly shorter for cows calving in the Drakensberg and the Dry Highveld bioregions. In terms of seasons, the ICP of cows bred in spring and summer was significantly shorter than that of cows bred in autumn and winter. Categorization of cows in year groupings indicates significant year effects.Keywords: Biome, bioregion, dam age, reproduction, seaso

Effect of ionophores and selenium supplementation on the composition of long-chain fatty acid in carcass fat of steers

(South African J of Animal Science, 2000, 30, Supplement 1: 131-133

Effects of stocking density on growth and skin quality of grower Nile crocodiles (Crocodylus niloticus)

Intensive Nile crocodile (Crocodylus niloticus) farming operates with considerable variation in housing and stocking density. In this study, current commercial stocking densities for crocodilians were investigated using 261 grower-phase crocodiles (15 months old, average total body length 94.5 cm, and average weight 2.7 kg). Low (2.60 m2 per crocodile), medium (1.24 m2 per crocodile), and high (0.41 m2 per crocodile) stocking densities were tested. Growth, morphometric measures, Fulton’s condition scores and skin qualities were assessed over a six-month (May - November 2017) period. High stocking density had no adverse effects on the growth of grower Nile crocodiles. Crocodiles stocked at medium and high densities outperformed those that were stocked at low density in Fulton’s body condition scores, change in body condition from the start to the end of the trial, and feed conversion efficiencies. However, the high and, to a lesser extent, the medium stocking densities resulted in lower skin quality scores compared with those in the low-density treatment because of teeth marks from more aggressive behaviour. The results indicated that the medium pen density treatment is closer to the ideal than either the high or low stocking density groups. Stocking densities that provide 0.41 m2 per crocodile or less should be avoided because of lower skin quality scores, which weigh more heavily than growth and feed efficiency responses in the financial viability of commercial crocodile farming in typical South African production systems

Description of a presumptive hepatopancreatic reovirus, and a putative gill parvovirus, in the freshwater crayfish Cherax quadricarinatus

The redclaw freshwater crayfish Cherax quadricarinatus has a reputation for being hardy and resistant to handling stress. However, in recent years, possibly since 1996, C. quadricarinatus farmers in northern Queensland have noted a decrease in stress resistance in their stock. A presumptive reovirus in the hepatopancreas, and a putative parvovirus in the gills, were associated with chronic mortalities in C. quadricarinatus at one northern Queensland farm. Hypertrophic nuclei with marginated chromatin were observed in gill epithelium in moribund crayfish which had recently been relocated to a laboratory from the holding tank facility on the farm. Affected nuclei appeared to be vacant or contained a faint granular basophilia in H&E stained sections. However, toluidine blue staining revealed a homogeneously granular appearance of the nuclei. Transmission electron microscopy revealed approximately 20 nm diameter virus-like particles within the nucleus. Eosinophilic, Feulgen-negative, cytoplasmic inclusions were observed in distal hepatopancreatocytes in 1 moribund C. quadricarinatus collected from the same on-farm holding tank approximately 6 mo later. This crayfish did not display the gill lesions. Transmission electron microscopy showed that the inclusions contained icosahedral virus particles 35 to 40 nm in diameter. The histopathology and preliminary virus morphology of the presumptive hepatopancreatic reovirus, and the histopathology, ultrastructural pathology and preliminary virus morphology of the putative gill parvovirus, are reported herein