________________________________________________________________________________ AbstractIncremental levels of sun-dried and coarsely ground cactus pear (Opuntia ficus-indica var. Algerian) cladodes were used to substitute part of the lucerne hay in balanced diets fed to Dorper wethers (n = 28; 33.90 ± 2.98 kg) during a trial period of 63 days. The three treatment diets (T0, T24 and T36) comprised respectively (air dry basis) 0, 240 and 360 g/kg Opuntia; 660, 410 and 285 g/kg lucerne hay; 300 g/kg maize meal; 0, 10 and 15 g/kg feed grade urea; and 40 g/kg molasses meal. Apparent DM digestibility coefficients increased significantly (0.714, 0.732, and 0.756) with Opuntia inclusion in diets. Feed dry matter (DM) intake (1.368, 1.345 and 1.317 kg DM/day) and average daily gain (117.8, 116.4 and 95.6 g/day) decreased slightly as Opuntia inclusion increased. Similar to previous studies the ingestion of Opuntia caused the production of wet faeces by the wethers. It was concluded that adequate nutrients were provided by these diets for maintenance and a moderate level of production in the Dorper wethers.________________________________________________________________________________

________________________________________________________________________________ AbstractA study was conducted to evaluate the effects of a rumen-specific, active live yeast (Saccharomyces cerevisiae; SC CNCM I-1077), alone or in combination with an ionophore (lasalocid-Na) in standard feedlot diets, on production performance and carcass quality of lambs. Sixty South African (S.A.) Mutton Merino lambs, weighing 25.7 ± 2.2 kg, were randomly allocated to four treatments (15 lambs per treatment) and further subdivided into five replicates per treatment (three lambs per replicate). The four dietary treatments consisted of an iso-nitrogenous and iso-energetic basal diet (177 g crude protein (CP)/kg dry matter (DM) and 276 g neutral detergent fibre (NDF)/kg DM) differing only in the additive included, i.e. (i) the control (C) diet (no additive), (ii) live yeast (SC) (220 g/ton), (iii) ionophore (G) (120 g/ton) and (iv) both live yeast with ionophore (SCG) at the same mentioned levels. After adaptation (8 days), the experimental diets were fed for 47 days in a finishing period. Feed intake and body weights were recorded weekly. At completion all animals were slaughtered (44.5 ± 3.8 kg) and the cold (2 °C) carcass weight and carcass characteristics recorded. Dietary treatment had no effect on feed intake, daily live weight gain, feed conversion ratio, carcass weight and carcass characteristics. Carcasses were leaner on the ionophore treatment (G) in comparison to the control diet (C). The results suggested that this rumen-specific live yeast included alone or in combination with an ionophore in finishing diets, containing less than 28% NDF/kg DM, did not affect performance and carcass traits of S.A. Mutton Merino lambs. _______________________________________________________________________________________

________________________________________________________________________________ AbstractThe influence of a synthetic or natural antioxidant and lipid saturation on the apparent digestibility of nutrients in a standard lamb finishing diet was investigated. The four dietary treatments consisted of the same basal diet, providing 187 g CP-, 355 g NDF-and 71 g EE per kg DM, but differing in supplemental lipid source (30 g/kg of either saturated beef tallow or unsaturated soybean oil) and type of antioxidant included (125 g/ton of either a synthetic or natural antioxidant). The digestibility study was conducted over a period of 12 days (including a 4-day adaptation to the faecal collection bags). Twenty-eight S.A. Mutton Merino lambs (45.1 ± 3.0 kg) were randomly allocated to the four dietary treatments (n = 7 lambs/treatment). Composite feed, feed refusal and faecal samples of individually penned lambs were collected for chemical analysis. The apparent digestibility coefficients, digestible nutrient and available energy content were calculated accordingly. The DMI of the lambs did not differ significantly between the various experimental diets. The inclusion of unsaturated soybean oil reduced the apparent digestibility of NDF in the diet. The apparent digestibility of NDF seems to be higher when a natural antioxidant was included in the diet. The comparatively negative effects of the unsaturated lipid source and synthetic antioxidant on the apparent digestibility of NDF were associated with a significantly lower digestible NDF content in the experimental diet. Accordingly, soybean oil resulted in a significantly lower ME content in the diet. However, estimating ME from DE with a constant factor of 0.8 probably underestimates the ME content of diets supplemented with lipids rich in unsaturated fatty acids. The latter are known to reduce methane production, and hence, energy losses. _______________________________________________________________________________________

No abstract

________________________________________________________________________________ AbstractA study was conducted to investigate the effects of a synthetic or natural antioxidant and fat saturation, in a standard feedlot diet, on fatty acid composition and oxidative stability of lamb. The four dietary treatments consisted of the same basal diet providing 187 g crude protein (CP), 355 g neutral detergent fibre (NDF), and 71 g ether extract (EE) per kg dry matter (DM), differing in fat source (30 g/kg of either saturated beef tallow or unsaturated soybean oil) and type of antioxidant included (125 g/t of either a synthetic or natural antioxidant). Eighty four S.A. Mutton Merino lambs weighing 27.6 ± 1.7 kg were divided into four groups and randomly allocated to four dietary treatments (n = 21 lambs/treatment) subdivided into 7 replicates/treatment (n = 3 lambs/replicate). After an adaptation period of 8 days, all lambs received complete diets for a further feeding period of 41 days. At termination of the study, seven lambs per treatment, weighing 45.1 ± 3.0 kg, were randomly selected and slaughtered. Loin chops from each carcass were used for fatty acid, colour (a * values) and thiobarbituric acid reactive substance (TBARS) analysis. Meat colour was determined on days 0 and 7 after being stored at 4 ºC under fluorescent light. The malonaldehyde content per kg meat was determined on days 0, 7 and 90 after being stored at -18 ºC in the dark. It was found that dietary treatment had no effect on colour stability as depicted in a * values. The malonaldehyde content per kg meat was higher on days 0 and 90 for the unsaturated soybean oil treatment. Beef tallow inclusion resulted in an increase in palmitoleic acid, where soybean oil inclusion resulted in an increase in linoleic and α-linolenic acids in both lean and subcutaneous fat tissue. Natural antioxidant inclusion in the diet only increased the palmitoleic acid content of subcutaneous fat. The results suggested that the fatty acid profile of lamb meat can be favourably manipulated by the source of fat included in the diet. ________________________________________________________________________________

No abstract

Inexpensive fibre sources might be used as an alternative to lucerne hay in diets for finishing lambs. Thus, effects of providing fibre from lucerne hay (LH), soyhulls (SH), maize stover (MS) and Eragrostis teff hay (ET) on the nutrient digestibility of diets of finishing lambs with comparable NDF and nutrient concentration were evaluated. Thirty-six individually housed Merino ram lambs (x̄ = 43.03, SD = 3.72 kg) were randomly allocated to four diets (n = 9 lambs/treatment). A digestibility study was conducted to determine the nutrient availability of these diets. Dry matter (DM) intake of SH (1436 g) was lower than ET (1716 g). No differences were recorded between treatments for digestibility of NDF (0.32 - 0.34), acid detergent fibre (ADF) (0.41 - 0.44), and ether extract (EE) (0.67 - 0.75), except that MS (0.23) had lower NDF digestibility. Digestibility of DM, organic matter (OM) and non-structural carbohydrates (NSC) were similar for the LH (0.72; 0.75; 0.96) and SH (0.70; 0.74; 0.95) diets, whereas digestibility of crude protein (CP) (0.71 vs. 0.68), metabolizable energy (ME) (9.49 vs. 8.90 MJ/kg DM), and the available ash fraction (0.39 vs. 0.28) were altered. The SH and ET (8.70 MJ/kg DM) treatments had similar ME concentrations, but ET had lower DM digestibility (0.68). The MS treatment had the lowest ME concentration (8.25 MJ/kg DM). The LH treatment resulted in overall better nutrient availability compared with SH, MS, and ET.

________________________________________________________________________________ AbstractThis study was conducted to evaluate the effect of different rumen fermentation modifiers (ionophores) in feedlot finisher diets on the production performance of S.A. Mutton Merino lambs. Monensin (16.4 mg/kg), lasalocid (33.0 mg/kg) or salinomycin (17.5 mg/kg) was incorporated into a commercial high-protein (398 g CP/kg DM) concentrate. Treatment diets consisted of maize meal (650 g/kg), lucerne hay (150 g/kg) and a protein concentrate (200 g/kg; containing an ionophore or not) to supply isonitrogenous (177 g CP/kg DM) total mixed diets during the experimental period. Sixty lambs (29.7 ± 2.5 kg) were randomly allocated to the treatment groups (n = 15/treatment) and each treatment was further subdivided into five replicates (n = 3/replicate). Individual body weight and average feed intake per replicate were recorded weekly and used to calculate the feed conversion ratio (FCR) and average daily gain (ADG). Ionophore treatment had no effect on any of the feedlot performance parameters measured (feed intake: 1379, 1434, 1534 and 1559 g DM/day; ADG: 298, 314, 340 and 329 g/day; FCR: 4.66, 4.58, 4.51 and 4.74 g DM intake/kg live weight gained for the Control, Monensin, Lasalocid and Salinomycin treatments, respectively. The results suggest the efficiency of the different rumen fermentation modifiers to be similar and financial implications and/or animal preference would influence their usage in sheep diets. ________________________________________________________________________________