Impact of feeding systems on carcass and meat quality in swamp buffalo (Bubalus bubalis)

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In Thailand, beef for human consumption is mainly derived from native cattle and buffaloes. Previously, buffaloes were used as draught animals in rice fields. Nowadays, farmers no longer raise buffaloes for working but rather for meat production. The predominant breed in Thailand is the swamp buffalo which is raised extensively. The demand for high-quality meat has been increasing due to changes in the socio-economic pattern of the population, such as an increasing standard of living and education.

The overall goals of this study were to compare carcass characteristics, meat quality and fatty acid profiles of swamp buffaloes fed diets with varying proportions of concentrate, roughage and pasture during the fattening period. In particular this study addresses the effect of concentrate supplementation in pasture-fed animals with the aim to establish recommendations for optimum ways of fattening Thai swamp buffalo.

Therefore, 24 male swamp buffaloes, 12 months of age, were randomly allocated to four groups of six animals each. One group grazed on a pasture of pure Guinea grass (Group 1), the second group grazed on a mix of Guinea grass and the legume Stylosanthes guianensis (Group 2), The remaining twelve buffaloes were raised in pens and fed either 1.5 % (n=6; Group 3) or 2.0 % (n=6; Group 4) of their body weight in concentrates. All animals had free access to fresh water. They were weighed at the beginning and the end of the fattening period and slaughtered at an average body weight of 398 kg (± 16). Hot (45 min post mortem) and chilled carcasses (24 h post mortem) were weighed and carcass length was determined. Dressing percentage was defined as the ratio of chilled carcass weight to live weight. Loin eye area was measured between the 12th and 13th rib. Proportions of retail cuts were determined both by dissection of the right half of the carcass according to “Meat and Livestock Commission” and of the left half according to Thai cutting style. pH of the meat was determined 45 min and 24 h after slaughter.

Meat quality parameters and fatty acid composition were determined on the longissimus dorsi muscle. Meat color was measured at 12th rib cut 48 h after slaughter. Water holding capacity was assessed via substance losses occurring during different procedures. Frozen samples of Longissimus dorsi muscle were thawed and kept at 4°C for 24 hours. Thereafter they were weighed and sealed in plastic to be boiled in a water bath and weighed again. In this way freezing and boiling loss were assessed. After that, six core pieces were removed from the boiled meat for shear force determination using an Instron apparatus. For the determination of grilling loss, samples were grilled in a convection oven until an internal temperature of 70°C was reached. The grilled samples were evaluated by trained panelists, who were asked to grade samples for tenderness, juiciness, flavor and overall acceptability. Samples from the Longissimus dorsi were minced and analyzed for moisture, protein and fat content. Susceptibility of lipids to oxidation was assessed by the 2-thiobarbituric acid method. Lipid was extracted from Longissimus dorsi samples for fatty acid analysis via capillary gaschromatography.

The carcass characteristics determined included dressing percentage, offal and external organs as well as loin eye area and carcass length. The concentrate-supplemented buffaloes of Group 3 had a significantly higher average daily weight gain than the other groups (569.8 g/day vs. 316.2, 354.3 and 539.7 g/day, respectively); likewise, hot and chilled carcasses were heavier in concentrate-supplemented buffaloes of Group 3 than in the other groups. In addition, dressing percentage and carcass lengths were higher in animals from this group. Loin eye area of concentrate-supplemented buffaloes of Group 3 was higher than in the other groups (49.08 cm2 vs. 39.76, 43.75 and 47.8 cm2, respectively). Concentrate feeding (Groups 3 and 4) significantly increased the weights of brisket and short loin; however, no feeding effect on weights of chuck, shank, rib, plate, flank, sirloin and round could be detected. The weights of Quadtriceps and Semimembranosus muscle and bones were higher in pasture-fed than in concentrate-supplemented buffaloes (4.50, 5.34 and 21.35 vs. 4.16, 4.90 and 16.25%, respectively). However, the weight of the Biceps femoris muscle and total fat were higher in concentrate-supplemented animals (6.53 and 11.90 vs. 6.11 and 3.43%, respectively). The weights of internal and external organs differed significantly between the groups. The weight of the external organs, of skin and tongue, as well as that of internal organs heart and spleen were higher in concentrate-supplemented than in pasture-fed buffaloes.

It became evident that meat from concentrate-supplemented buffaloes was significantly redder in color (higher a* value) than that of buffaloes raised on pasture. The pH of the meat assessed 45 min and 24 hours were not affected by treatment, but after 24 hours it was higher in concentrate-supplemented buffaloes (Group 3) than in the other groups (5.96 vs. 5.83, 5.77 and 5.70 in Group 1, 2 and 4, respectively). The water holding capacity in terms of drip and thawing loss was lower in grass-fed buffalos than in the groups fed concentrates, whereas cooking and grilling loss remained unaffected by diet. Fat, protein and moisture percentages differed significantly between groups. Concentrate-supplemented buffaloes had higher protein and fat percentage than pasture-fed buffaloes. Meat from the concentrate-supplemented buffaloes (Group 4) was more tender and juicy than that from other groups. The meat of the Longissimus dorsi of concentrate-supplemented buffaloes (Group 3) had higher cholesterol (59.2 vs. 45.4, 46.2 and 53.5 mg/100g, respectively) contents than that of the other groups. However, concentrate supplementation decreased the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA). There was an interaction between grass and concentrate allowance for polyunsaturated fatty acids (PUFA): SFA ratio. The ratio was higher when buffaloes grazed on grass plus legume pastures (Group 2) in comparison those concentrate-supplemented (0.22 vs. 0.20, 0.12 and 0.15, respectively). The ratio of n-6/n-3 PUFA was significantly higher in concentrate-supplemented than in pasture-fed groups (4.73 vs. 1.78, respectively).

The present study revealed that the feeding system had a significant effect on growth rate and most carcass and meat quality characters. The amount of concentrate was of minor importance. The meat of concentrate-supplemented buffaloes showed a greater potential for postmortem tenderization through aging. It was more tender after 7 days of storage than the meat of pasture-fed buffaloes. Longissimus dorsi muscle from pasture-fed buffaloes tended to be darker when compared with concentrate-supplemented buffaloes. Moreover, meat from pasture-fed buffaloes had a greater shelf life than meat from concentrate-supplemented buffaloes. Pasture feeding had a positive effect on the fatty acid profile, resulting in higher n-3 fatty acid and CLA percentages. It exhibited a lower n-6/n-3 ratio, and hence, ought to be beneficial for human health.

It may be concluded that concentrate supplementation during the final fattening period of swamp buffaloes affected both production system and carcass traits. Therefore, under certain circumstances, concentrate supplementation will be of economic benefit. However, from the human health perspective, meat of grass-fed buffaloes is recommended due to the lower fat concentration and the more favorable n-3 and n-6 PUFA profile.