Mutton and lamb sales continue to grow globally at a rate of 5% per year. However, sheep farming struggles with low profit margins due to high feed costs and modest carcass yields. Selecting those sheep expected to convert feed efficiently and have high carcass merit, as early as possible in their life cycle, could significantly improve the profitability of sheep farming. Unfortunately, direct measurement of feed conversion efficiency (via residual feed intake (RFI)) and carcass merit is a labor-intensive and expensive procedure. Thus, indirect, marker-assisted evaluation of these traits has been explored as a means of reducing the cost of its direct measurement. One promising and potentially inexpensive route to discover biomarkers of RFI and/or carcass merit is metabolomics. Using quantitative metabolomics, we profiled the blood serum metabolome (i.e., the sum of all measurable metabolites) associated with sheep RFI and carcass merit, and identified candidate biomarkers of these traits. The study included 165 crossbred ram-lambs that underwent direct measurement of feed consumption to determine their RFI classification (i.e., low versus high) using the GrowSafe System over a period 40 days. Carcass merit was evaluated after slaughter using standardized methods. Prior to being sent to slaughter one blood sample was drawn from each animal, and serum prepared and frozen at -80 oC to limit metabolite degradation. A subset of the serum samples was selected based on divergent RFI and carcass quality for further metabolomic analyses. The analyses were conducted using three analytical methods (nuclear magnetic resonance spectroscopy, liquid chromatography mass spectrometry and inductively coupled mass spectrometry), which permitted the identification and quantification of 161 unique metabolites. Biomarker analyses identified three significant (P-value < 0.05) candidate biomarkers of sheep RFI (AUC=0.80), seven candidate biomarkers of carcass yield grade (AUC=0.77) and one candidate biomarker of carcass muscle to bone ratio (AUC=0.74). The identified biomarkers appear to have roles in regulating energy metabolism and protein synthesis. These results suggest that serum metabolites could be used to categorize and predict sheep for their RFI and carcass merit. Further validation using a larger (3X) and more diverse cohort of sheep is required to confirm these findings.

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A 2-yr study to evaluate the effectiveness of whole sunflower seed as a source of fat was conducted with 18 primiparous and 31 multiparous Holstein cows. The three diets evaluated were a basal diet based on barley (control), a basal diet supplemented with 2.7% tallow, and a basal diet supplemented with 7.1% whole sunflower seeds. The DMI of lactating cows during the 16-wk test period was not influenced by supplementation with either sunflower seeds or tallow. Milk production was 34.4, 34.6, and 35.5 kg/d for cows fed the control diet or the diets supplemented with sunflower or tallow, respectively, and was not influenced by diet. The production and concentrations of milk protein, fat, and SNF also were not influenced by diet. The concentrations of C6:0 to C14:1 fatty acids were highest in the milk of cows fed the control diet. The concentrations of C10:0 to C16:1 were higher when cows were fed the diet with the tallow supplement than when they were fed the diet with the sunflower supplement. However, the concentrations of C18:0 to C18:2 and C20:0 were higher in the milk of cows that were fed the sunflower supplement than in the milk of cows that were fed the tallow supplement or the control diet. Concentrations of individual VFA and the ratio of acetate to propionate were not influenced by diet. Body weight, body condition score, and reproduction parameters were similar for all diets, suggesting that there were no effects on subsequent production. The performance of cows fed whole sunflower seeds as a source of energy appeared to be similar to the performance of cows fed traditional high energy diets based on barley. The fatty acid profile of the milk of cows fed diets supplemented with sunflower seeds was more favorable than that of the milk of cows fed diets supplemented with tallow.

Early detection of sheep pregnancy and the prediction of how many lambs a pregnant ewe delivers affects sheep farmers in a number of ways, most notably with regard to feed management, lambing rate, and sheep/lamb health. The standard practice for direct detection of sheep pregnancy and litter size (PLS) is ultrasonography. However, this approach has a number of limitations. Indirect measurement of PLS using blood biomarkers could offer a simpler, faster and earlier route to PLS detection. Therefore, we undertook a large-scale metabolomics study to identify and validate predictive serum biomarkers of sheep PLS. We conducted a longitudinal experiment that analyzed 131 serum samples over five timepoints (from seven days pre-conception to 70 days post-conception) from six commercial flocks in Alberta and Ontario, Canada. Using LC–MS/MS and NMR, we identified and quantified 107 metabolites in each sample. We also identified three panels of serum metabolite biomarkers that can predict ewe PLS as early as 50 days after breeding. These biomarkers were then validated in separate flocks consisting of 243 animals yielding areas-under-the-receiver-operating-characteristic-curve (AU-ROC) of 0.81–0.93. The identified biomarkers could lead to the development of a simple, low-cost blood test to measure PLS at an early stage of pregnancy, which could help optimize reproductive management on sheep farms.

Markus, S. B., Aalhus, J. L., Janz, J. A. M. and Larsen, I. L. 2011. A survey comparing meat quality attributes of beef from credence attribute-based production systems. Can. J. Anim. Sci. 91: 283–294. Two branded beef programs based on producer-defined production systems differentiated by intangible credence attributes (Organic and Natural) were compared with Commodity beef to determine meat quality and assess consumer acceptability. In each of four slaughter seasons (winter, spring, summer and fall) longissimus lumborum muscle samples were collected from two industry slaughter plants; Organic n=30, 30, 27 and 31; Natural n=30, 27, 29 and 25; Commodity 1 n=12 and 18 for spring and summer, respectively; Commodity 2 n=14 and 12 for spring and fall, respectively. Samples were vacuum packaged and aged for 16±2 d at 2°C. Seasonal effects (P<0.01) were evident for mean shear force, composition, drip loss, colour and pH. While all mean shear values were classified as being tender (<5.6 kg), a smaller proportion of steaks were classified as tender in the Organic beef compared with the Natural and Commodity beef (55.9 vs. 70.3 and 78.6%; P<0.01), indicating that even after industry normal ageing times there was higher tenderness variability in the Organic beef. Fat content (SEM=0.23; P<0.01) was lowest for the Organic line (3.98%) with Natural (5.34%) and Commodity being intermediate (5.73%). Some statistically significant differences (P<0.05) in mean scores for aroma, juiciness, flavour, tenderness and overall acceptability of cooked beef steaks were observed amongst the three production systems when samples were not matched on the basis of intramuscular fat (IMF). Clearly there are measureable differences in quality between “credence” based production systems and commodity beef with an overall better quality in Commodity beef. However, if the consumer is willing to pay for credence-based attributes then there is an opportunity for these production systems to improve the quality of their product, specifically in respect to age at slaughter and content of IMF.