Comparison and analysis on sheep meat quality and flavor under pasture-based fattening contrast to intensive pasture-based feeding system

Abstract

Title of the manuscript:Comparison and analysis on sheep meat quality and flavor under pasture-based fattening contrast to intensive pasture-based feeding system ABSTRACTObjective: The objective of this study was to investigate the effect of 4-month intensive feeding on the meat quality, fatty acid profile, flavor and growth performance of grazing Hulunbuir Sheep. Methods:The Selected Hulunbuir sheep (HBS) was selected after born in 4-month pasture rearing as the experimental animal (n=44, female, 4-month old, average body weight 23.8 ± 2.2kg) with excellent meat flavor, then divided equally into pasture-based grazing fattening (PAS) and concentrateincluded intensive fattening (CON) groups for another 4-month finishingattening to investigate the influences on meat quality, fatty acid profile, flavor and growth performance. When finished fattening, all animals were slaughtered to collect musculus longissimus dorsi subcutaneous adipose tissue. Results:The results showed lambs in CON group got significantly higher live weight (LW,), hot carcass weight (HCW) and dressing percentage (DP). The CON group had significantly (P<0.05) higher value of redness (a*), lightness (L*) and water holding capacity (WHC) (P<0.05), significantly lower value (P<0.05) of Warner-Bratzler shear force (WBSF) than the PAS group(P<0.05). The subcutaneous fat from CON group lambs demonstrated a significantly higher content of C18:1 and C18:2 (P<0.05), but lower C14:0 and C16:0, indicating an increased degree of unsaturated fatty acid (USFA). The content of 4methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA) and 4-methylnonanoic acid (MNA) had increased 2-4 times, representing a more intense odor in the CON group. However, the A c c e p t e d A r t i c l evalues were still lower than most sheep breeds reported, indicating the indoor feeding system could not deteriorate the excellent meat characteristic of HBS fundamentally. Conclusion:It was evident that lambs in CON group exhibited a better meat production performancehigher growth rate, improved in meat color, texture and healthier eating quality and better fatty acid profile through intensive pasture-weaned concentrate included based intensive fattening system, which offers a good alternative regimen for lamb finishing and has a wide prospection in the Hulunbuir sheepmeat industry.The reasoning for differences above between two groups were analyzed elaborately,either.

Review of Feeding Systems Affecting Production, Carcass Attributes, and Meat Quality of Ovine and Caprine Species

“…Feeding systems greatly influence the growth rate and carcass attributes of sheep and goats ( Table 1 ). Regarding sheep lambs, grazing on natural pasture reduced the average daily gain (ADG), slaughter live weight (SLW), hot carcass weight (HCW), cold carcass weight (CCW), and dressing percentage (DP) of lambs compared with exclusive concentrate diets [ 4 , 7 , 34 , 35 , 36 , 37 , 38 , 39 ]. These effects could be associated with lower forage mass intake and higher energy demand for maneuvering the grazing system [ 40 , 41 , 42 , 43 ], a higher digestibility of concentrate diets [ 44 ], lower gastrointestinal content of concentrates [ 45 , 46 ] and high or low adaptation of the breed to the feeding environment.…”

“…The finishing system has a marked effect on meat color, including lightness ( L *), redness ( a *), and yellowness ( b *) ( Table 2 ), thus impacting consumer preferences [ 62 , 63 ]. Regarding sheep lambs, compared with concentrate-fed lambs, the longissimus muscle of the pasture-fed lambs has a lower L *, but comparable or lower a * and b * [ 7 , 27 , 36 ]. This indicates that concentrate-based diets lead to desirable attributes of longissimus for lamb meat.…”

“…In fact, meat tenderness is negatively correlated with the Warner-Bratzler shear force (WBSF), which depends on several factors, including ultimate pH, intramuscular fat (IMF), collagen contents, and muscle fiber length [ 70 ]. Meat juiciness has a strong positive correlation with water-holding capacity (WHC) and a negative correlation with drip loss (DL), water loss (WL), and cooking loss (CL) [ 36 , 70 , 71 ].…”

“…Studies have showed that, compared with concentrate-fed lambs, the meat of pasture-fed lambs is less tender and juicy, indicated by significantly higher WBSF and lower WHC or higher CL and DL, respectively [ 36 , 70 , 71 , 72 , 73 ]. Concentrates enhance the tenderness and juiciness of lamb meat by reducing the fiber content in the muscles, strength of connective tissue [ 74 ], and disintegrating myofibrillar proteins and connective tissue, all of which increase the WHC of proteins [ 75 ].…”

“…Research shows that the meat of pasture-fed lambs has a superior flavor than concentrate-fed lambs [ 78 ]. Moreover, lambs raised on pastures have lower levels of 4-ethyloctanoic acid (EOA), 4-methyloctanoic acid (MOA), and 4-methylnonanoic acid (MNA) and higher levels of 4-methylphenol (MP) compared to concentrate-fed lambs [ 36 ] ( Table 4 ). This indicates that the meat flavor of pasture-grazed lambs was better than those of their concentrate-finished counterparts because EOA, MOA, and MNA content influence “mutton” flavor and MP is associated with distinct “pastoral” flavor [ 79 ].…”