The effect of lucerne (Medicago sativa) hay quality on milk production and composition of Jersey cows

The influence of lucerne hay quality on the milk production potential and milk composition of Jersey cows was investigated. Three different grades of lucerne hay (Prime, Grade 1, Grade 2; selected according to the New Lucerne Quality Index) were included in a total mixed ration (TMR) and fed to lactating cows. The three dietary treatments consisted of the same basal diet (53% lucerne hay, 7% wheat straw and 40% concentrate), differing only with respect to the lucerne hay quality. Fifty-seven lactating Jersey cows (389 ± 39.07 kg) were selected and blocked according to production potential (milk production, days in lactation, as well as lactation number) and randomly allocated to each of the dietary treatments (n = 19 animals per treatment). After a dietary adaptation period of 14 days, each treatment received their respective diets for the remaining period of 54 days. Average dry matter intake (DMI) and individual milk production was measured on a daily basis and production parameters were calculated accordingly. Milk composition samples were collected every second week. Grade 2 lucerne hay significantly decreased the voluntary DMI of the cows. However, the Prime lucerne hay significantly increased the metabolizable energy intake (MEI), as well as both the protein and milk urea nitrogen (MUN) content of the Jersey milk, compared to the Grade 1 and Grade 2 treatments. In contrast, the efficiency with which ME is utilized for milk production was significantly decreased following Prime lucerne hay inclusion. Milk yield as such was not affected by dietary treatment. Results of the present study seem to indicate that lucerne hay quality does affect the production performance, milk composition and efficiency of energy utilized for milk production purposes of Jersey cows.Keywords: Dairy, index, lactation, nutrient, performance, roughage, TM

The effect of dietary lipid saturation and antioxidant source on the nutrient digestibility of lamb finishing diets

The 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.Keywords: Beef tallow, fatty acid, flavonoid, methane, soybean oi

Fatty acid composition and oxidative stability of lambs’ meat as affected by a bioflavonoid antioxidant and fat sources

A 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.Keywords: Antioxidants, dietary fat saturation, feedlot lamb

The effect of dietary lipid saturation and monensin-Na on the CLA content of lambs’ meat

A study was conducted to investigate the influence of an ionophore antibiotic and lipid saturation within a standard finishing diet on the conjugated linoleic acid (CLA) content of lambs’ meat. Two identical sheep grower diets containing 145 g CP, 282 g NDF and 45 g EE per kg DM were formulated. One diet contained no ionophore antibiotic and the other monensin-Na included at 165 g/ton. These two basal diets were supplemented, according to a 2 x 3 factorial design, with three lipid sources [i.e. 20 g/kg of either beef tallow, sunflower oil or a CLA oil concentrate] differing in saturation level and fatty acid profile. Sixty South African Mutton Merino lambs (31.15 ± 2.83 kg) were randomly allocated to the six treatments. After dietary adaptation of 10 days, the lambs received their respective treatment diets for the remaining period of 51 days. At the end of the study seven lambs (45.11 ± 2.99 kg) were randomly selected per treatment and slaughtered. Muscle and subcutaneous fat tissue from loin chops of each carcass were used for lipid extraction and fatty acid analysis. The supplementation of CLA oil in the diet resulted in a significantly lower vaccenic acid concentration of lamb muscle tissue. In contrast, supplementing sunflower oil increased the linoleic acid concentration of only the subcutaneous fat tissue significantly. Sunflower- and CLA oil supplementation increased the cis-9, trans-11 CLA isomer of both subcutaneous fat and muscle tissues, whereas only the CLA concentrate increased the trans-10, cis-12 isomer of both mentioned tissues significantly. The dietary inclusion of monensin-Na decreased the vaccenic-, linoleic- and CLA (cis-9, trans-11 isomer) concentrations of both lamb subcutaneous fat and muscle tissues significantly. The manipulation of the CLA content of lamb seems to be effective when adding either sunflower oil or a CLA oil concentrate to the finishing diet of lambs. However, this effect is inhibited by the addition of monensin-Na to the same diet.Keywords: Conjugated linoleic acid, cis-9, trans-11 CLA isomer, tallow, sunflower oil, subcutaneous fa

The effects of an active live yeast product on the growth performance of finishing lambs

A 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.Keywords: Feedlot lambs, ionophore, live yeas

The effect of dietary lipid saturation and antioxidant type on the performance of finishing lambs

The effect on production performance of a synthetic or natural antioxidant and lipid saturation in the finishing diets of lambs was investigated. The four dietary treatments consisted of the same basal diet (187 g CP, 355 g NDF, and 71 g EE per kg DM), differing only in regard to the supplemental lipid source (30 g/kg of either saturated beef tallow or unsaturated soybean oil) and type of antioxidant (125 g/ton of either a synthetic or natural antioxidant) included, in a 2 x 2 factorial design experiment. Eighty-four S.A. Mutton Merino lambs (27.64 ± 1.72 kg) were randomly allocated to the four dietary treatments (n = 21 lambs per treatment) and subdivided into 7 replicates per treatment (n = 3 lambs per replicate). After a dietary adaptation period of 8 days, all lambs received the respective experimental diets for the remaining period (41 days). The average daily DM feed intake, weight gain and feed efficiency was calculated accordingly. No significant differences in DMI, ADG and the efficiency with which ingested feed were utilized (FCR), were recorded for the treatments. However, the addition of unsaturated soybean oil to the diet significantly increased the efficiency with which the ME of the diet was utilized. In contrast with the natural antioxidant, the inclusion of unsaturated soybean oil in the diet containing a synthetic antioxidant, resulted in a significant lower MEI by the lambs – indicating that a lipid x antioxidant interaction occurred. Results of the present study seem to indicate that dietary lipid saturation in the finishing diets of lambs had no influence on their growth performance. However, a more efficient utilisation of ME in the finishing diet containing unsaturated soybean oil, compared to the saturated beef tallow, did occur.Keywords: Fatty acid, flavonoid, metabolizable energy, oil, production, sheep, soybean, tallo