Growth performance blood parameters and meat quality in finishing Dohne Merino Lambs reared under single - or paired-pen Housing

Abstract

The study was designed to evaluate the effect of dietary vitamin E and selenium on growth performance, blood parameters, and meat quality of finishing Dohne Merino lambs reared under two types of confinement. Twenty four lambs with an average body weight of 25 .8 ± 2. 7 kg were used. The lambs were randomly assigned to four treatment combinations: single-pen housing with no extra vitamin E-selenium supplementation, single-pen housing with extra vitamin Eselenium supplementation, paired-pen housing with no extra vitamin E-selenium supplementation, and paired-pen housing with extra vitamin E-selenium supplementation, in a completely randomized design. The results showed no significant differences (P > 0.05) on the overall weight gain and overall feed conversion ratio across the four treatments. Lambs supplemented with vitamin E-Se consumed more feed (65.01 kg) over the entire feeding period as compared to the lambs that were not offered the supplements (60.37 kg). An interaction between supplement and housing condition was observed on rectal temperature on the last day of the experiment where animals housed in pairs had a higher mean rectal temperature (39.3 °C) as compared to those housed individually (38.8°C). The results showed that most of the hematological indices were not significantly (P < 0.05) affected by the dietary supplement and housing type, with the exception of red blood cell (RBC), hematocrit/packed cell volume (HCT/PCV), and mean corpuscular haemoglobin concentration (MCHC). For these parameters, the supplemented lambs had higher RBC (12.6l x 1012/L), HCT/PCV (28.88 %) and MCHC (32.24 g/dL) counts/levels as compared to the non-supplemented animals (RBC, 11.17x 1012/L; HCT/PCV, 24.87 %; and MCHC, 15.96 g/dL) and irrespective of the housing type. Superoxide dismutase and glucose levels were significantly (P <0.05) affected by housing type only, with the higher means of 0.05 u/mL and 3.95 mmol/L, respectively, being observed in companion

group as compared to the solitary confinement group (0.03 u/mL and 3.65 mmol/L, respectively). At the end of feeding trial, the animals were slaughtered to determine meat quality characteristics. Results from this analysis showed that most of the carcass measurements and meat qualities were not significantly (P < 0.05) influenced by the dietary vitamin E-selenium supplementation and housing type with the exception of slaughter weight , dressing percentage and pHu ( on shelf life). These parameters were higher in lambs fed with the dietary vitamin Eselenium than in the control group. A significant (P < 0.05) interaction between supplementation x housing was observed for drip loss percentage and carcass length. All in all, the results of this study provided a valuable insight into the impact of dietary vitamin E and selenium on lamb performance, physiological parameters, blood parameters and meat quality. Dietary vitamin E and selenium induced more appetite, as the supplemented group consumed more feed than the control group. On the other hand, the RBC, HCT/PCV, MCHC, slaughter weight, dressing percentage and pHu were higher in the supplemented group than the control group. It can be concluded that the companion housing and solitary confinement caused different levels of stress, as an interaction was observed on the rectal temperature, drip loss percentage and carcass length.