Effects of supplementation with fish oil and barium selenate on performance, carcass characteristics and muscle fatty acid composition of late season lamb finished on grass-based or concentrate-based diets

Abstract

The objectives of this study were to investigate the effects of fish oil supplementation on performance and muscle fatty acid composition of hill lambs finished on grass-based or concentrate-based diets, and to examine the interaction with selenium (Se) status. In September 2006, 180 entire male lambs of mixed breeds were sourced from six hill farms after weaning and finished on five dietary treatments: grazed grass (GG), grass 10.4 kg/day cereal-based concentrate (GC), grass 10.4 kg/day cereal-based concentrate enriched with fish oil (GF), ad libitum cereal-based concentrate (HC) and ad libitum fish oil-enriched concentrate (HF). Within each treatment, half of the lambs were also supplemented with barium selenate by subcutaneous injection. At the start of the trial, the proportion of lambs with a marginal (,0.76 mmol/l) or deficient (,0.38 mmol/l) plasma Se status was 0.84 and 0.39, respectively. Compared with control lambs, GG lambs treated with Se had higher ( P , 0.01) plasma Se levels, whereas erythrocyte glutathione peroxidase activity was higher ( P , 0.01) for Se-supplemented lambs fed diets GG and GF. However, Se supplementation had no effects on any aspect of animal performance. Fish oil increased ( P , 0.05) levels of 22:5n-3 and 22:6n-3 in the Longissimus dorsi of HF lambs but otherwise had no effect on the health attributes of lamb meat. There were no significant effects of fish oil on dry matter intake, animal performance or lamb carcass characteristics. Daily carcass weight gain (CWG; P , 0.001), carcass weight ( P , 0.01) and conformation score ( P , 0.01) increased with increasing concentrate inputs. Lambs fed concentrate-based diets achieved a higher mean CWG ( P , 0.001), dressing proportion ( P , 0.001) and carcass weight ( P , 0.011), and were slaughtered up to 8.3 days earlier ( P , 0.05) and at 1.2 kg lower ( P , 0.05) live weight than pasture-fed lambs. However, carcasses from grass-fed lambs contained lower levels of perinephric and retroperitoneal fat ( P , 0.05), and had less fat over the Iliocostalis thoracis ( P , 0.001) and Obliquus internus abdominis ( P , 0.05). Meat from grass-fed lambs also had lower levels of 18:2n-6 and total n-6 fatty acids compared with those finished indoors. The results of this study demonstrate that fish oil supplementation has some benefits for the health attributes of meat from lambs fed concentrate-based diets but not grass-based diets. Supplementing Se-deficient lambs with barium selenate will improve Se status of lambs fed zero-concentrate diets, but has no additional benefit when lambs are already consuming their daily Se requirement from concentrates or when fish oil-enriched diets are fed.

Camelina sativa affects the fatty acid contents in M. longissimus muscle of lambs

“…Elevating the level of the UFA content in lamb longissimus dorsi muscle may have a deleterious effect on lipid stability. This was confirmed in the experiment by Moloney et al . They concluded that the ratio of PUFA to vitamin E, that is required to prevent loss of oxidation and prolong the shelf‐life of lamb containing elevated levels of PUFA, remains to be determined.…”

“…The seeds may alter the fatty acid composition in muscle and adipose tissue. Additionally, numerous studies involving lambs indicate that dietary fat supplements, as the total source of UFAs, may increase conjugated isomers content, but may not always affect the proportion of saturated and UFAs . Type and quantity of dietary fatty acids determine the direction of rumen metabolism, and consequently, the fatty acid composition of the meat.…”

Effects of increasing dietary concentrations of fish oil on lamb performance, ruminal fermentation, and leptin gene expression in perirenal fat

“…Overall, in studies in which fish oil concentrations were approximately 10 g/kg, final weight, average daily gain, and feed efficiency were unaffected (Toral et al, 2009;Annett et al, 2011;Ferreira et al, 2014), but when the fish oil concentrations were above 30 g/kg, the intake and average daily gain were reduced (Kitessa et al, 2001;Wachira et al, 2002;Marinova et al, 2007). Annett et al (2011) observed that with 35 g/kg fish oil, the subcutaneous fat depth over the leg area in lambs increased slightly and Marinova et al (2007) reported that a diet with 10 g/kg fish oil mixed with 20 g/kg sunflower oil reduced the subcutaneous fat in the loin, but intramuscular fat was higher in the shoulder.…”

“…Fish oil has been incorporated into lamb diets at concentrations of 20-30 g/kg, based on forage or concentrate, with no effect on intake or daily gain (Marinova et al, 2007;Toral et al, 2009;Annett et al, 2011). Other studies have partially replaced vegetable oils with fish oil and attempted to avoid the negative effects of the omega-3 polyunsaturated fatty acids, which are present at high concentrations in fish oil, on lamb performance.…”

Influence of dietary magnesium and selenium levels in finishing diets on growth performance and carcass meat quality of feedlot Pelibuey lambs

“…This difference was only noticeable in these saturated fatty acids. Annett et al (2011) observed that injection Se (50 mg Se per lamb), as barium selenite, increased (P<0.05) the level of 20:4 n-6 in lamb meat but resulted in lower (P<0.001) levels of 22:6 n-3. However, Se had no effects on any of the health attributes of lamb meat.…”