Predicting the chemical composition of the body and the carcass of hair sheep using body parts and carcass measurements

Fortification of diets with omega-3 long-chain polyunsaturated fatty acids enhances feedlot performance, intramuscular fat content, fat melting point, and carcass characteristics of Tattykeel Australian White MARGRA lambs

Meat eating quality indices such as intramuscular fat content (IMF) and fat melting point (FMP) of the Longissimus thoracis et lumborum muscle and the feedlot performance, carcass traits, and commercial wholesale cuts of lot-fed Tattykeel Australian White (TAW) MARGRA lambs as a result of dietary fortification of the diet with omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) were evaluated. A total of 75 TAW MARGRA lambs at 6 months of age with an average liveweight of 30 ± 1.2 kg were used. The lambs were randomly allocated to the following three dietary treatments of 25 lambs each in a 47-day feeding trial using a completely randomized experimental design: (1) control diet of hay plus pellets without omega-3 oil, (2) hay plus commercial whole grain pellets (MSM) without omega-3 oil, and (3) hay plus pellets fortified with omega-3 oil. It was hypothesized that dietary supplementation with omega-3 fortified pellets will improve feedlot performance, meat-eating quality indices of IMF, FMP, and carcass characteristics. Lot-fed lambs on the MSM whole grain had the highest feed intake of 1.69 kg/day, followed by the control at 1.57 kg/day and the lowest in the omega-3 diet at 1.01 kg/day (p = 0.0001). However, the omega-3 diet had the highest average daily gain of 230 g/head/day (p = 0.0001), indicating the greatest feed efficiency since it had the best growth response with minimal feed intake. Post-slaughter evaluation of the Longissimus thoracis et lumborum muscle revealed significant treatment variations in IMF (p = 0.0001), FMP (p = 0.0001), pH (p = 0.0380), and wholesale French rack primal cut (p = 0.0001). Strong correlations (p < 0.05) between liveweight, temperature, pH, FMP, and IMF were observed. Similarly, significant correlations between carcass characteristics of total saleable meat yield, lean trim, fat trims, bones, and leg shank were evident (p < 0.05). However, there were no treatment differences in the final liveweight, GR fat depth, hot standard carcass weight, or dressing percentage. The findings indicate that feedlot performance, meat-eating quality traits such as IMF and FMP, and commercial wholesale French rack cuts can be further improved during feedlot finishing of TAW MARGRA lambs through dietary supplementation with omega-3 oils, and hence the tested hypothesis of improved meat quality attributes is partially confirmed.

Carcass characteristics of farmed fallow deer bucks

The average body weight of the 20-21-month-old bucks was 48,00 kg, with an average cold carcass weight of 24,08 kg (Table 1). Research by Żmijewski et al. (2020) showed an average body weight of more than 48 kg in 18-month-old deer bucks, with an average cold carcass weight of 26 kg. According to Volpelli et al. (2002), animals of the same age had an average body weight of 42 kg and a cold carcass weight of 24 kg. Those results are similar to the values presented in this study, which suggests that the body development of the animals studied was normal. null The average carcass weight of 24-month-old fallow deer acquired in natural hunting grounds has been found to be 36,2 kg (Dzierżyńska-Cybulko and Fruziński, 1997). It is worth noting that animals living in the wild are more physically active than farm-raised animals, which may be reflected in differences in their average body weight. The differences between values may be linked to many factors, e.g. health, activity, and/or the quality and amount of food in the diet. It should also be noted that deer body weight differs during the hunting season and off-season, while farmed animals can be slaughtered all year long. The measurements presented in Table 1 are an important element of carcass assessment. Both the carcass proportions and the animal’s individual development can be determined on the basis of these measurements. The average carcass length was 135,67 cm and was statistically significantly correlated (P ≤ 0,01) with body weight (Tables 1 and 2). Żmijewski et al. (2020) reported an average side length of 94 cm in fallow deer. This differs significantly from the data presented in our study, which can be explained by the use of different research methodologies. null A statistically significant relationship (P ≤ 0,01) was found between chest girth and body weight. Among height measurements, a significant relationship (P ≤ 0,05) was noted between height at the withers and body weight, and a highly statistically significant (P ≤ 0,01) relationship between rump height and body weight, as presented in Table 2. The cold dressing percentage was 50,09%, which is similar to the values obtained by Dzierżyńska-Cybulko and Fruziński (1997), ranging from 48,7% to 56,8%. According to Summer et al. (1997), 18-24-month-old fallow deer bucks can attain a dressing percentage of up to 56%, which is higher than the result presented here. Based on hot carcass weights, Stanisz et al. (2015) and Volpelli et al. (2002) estimated dressing percentages of 63,3% and 57,7%, respectively. The differences in the results may stem from differences in research methodologies, including the use of hot carcass weight rather than cold carcass weight to calculate dressing percentage. The combined percentage share of inedible elements (skin, head, and lower limbs) in fallow deer from the research farm was calculated to be 15,42%. Żmijewski et al. (2020) reported a value of 12,48%, while Stanisz et al. (2015) estimated the weight of the head, skin, and lower limbs to be 2,41 kg, 4,31 kg, and 1,44 kg, respectively. In our study, the head and lower limb weights were higher (2,89 kg and 2,06 kg respectively), while the skin weight was lower (2,44 kg). The difference may be attributed to differences in the age of the animals. The internal organs, i.e. the heart, liver, spleen, and kidneys, together constituted 2,86% of the animal’s body weight (Table 3). A statistically significant positive relationship (P ≤ 0,01) was shown between the weight of the liver and body weight (Table 4). Stanisz et al. (2015) reported heart, kidney and liver weight of 0,41 kg, 0,12 kg, and 0,95 kg, respectively. The corresponding values in the present study were 0,34 kg, 0,26 kg, and 0,62 kg. It is worth noting that the data used for comparison pertained to 32-month-old bucks, resulting in significantly different internal organ weights. null null Research by Czajkowska and Czaplejewicz (2020) showed that the average heart weight of 2-3-year-old fallow deer was 0,28 kg, while the heart weight in our research was 0,06 kg higher. The difference in heart weight can be attributed to different methods of extracting the organ, including different amounts of fat tissue left adhering to the heart. An important attribute of carcass quality is the percentage share of the various cuts. In the present study, the rump had the largest percentage share, amounting to about 37% of the total carcass weight, followed by the shoulders (19,49%) and the loin (16,60%). The combined weight of all cuts was 24 kg (98,97%). Stanisz et al. (2015), in 32-month-old fallow deer, found that the loin and the shoulders constituted 17,7% and 16,7%, respectively, of the carcass weight. Żmijewski et al. (2020) reported the rump, loin and shoulder cuts to be 38,42%, 14,42%, and 15,50% of the carcass weight. Those numbers confirm that the rump accounts for the highest percentage share of the carcass, amounting to more than 37% of the overall carcass weight. It should be noted that detailed comparison of the data obtained in the present study with the results of other research may be problematic due to differing dissection methods. The present study showed a highly significant (P ≤ 0,01) relationship between the shoulder, loin, and rump weights and carcass weight. The correlation coefficients ranged from 0,97 to 0,99. Łebacka and Gardzielewska (1975) noted similar relationships for loin and shoulder weights in red deer (r = 0,83 and r = 0,98, respectively). Similarly, Janiszewski (2009) found a highly statistically significant relationship between the weights of the cuts and carcass weight in red deer. For example, the correlation coefficients for the rump and shoulders were r = 0,82 and r = 0,84, respectively. A pronounced relationship between rump weight and carcass weight was also noted by Trziszka (1975), with a correlation coefficient (r = 0,95) very similar to that obtained in the present study. This confirms that calculating correlations between the weights of cuts can enable carcass assessment without the need for dissection. To conclude, the research results confirmed that there are clear relationships between the carcass parameters determined in the study (Table 5), which can serve as a basis for developing indirect methods of assessing the carcasses of farm-raised fallow deer. null Calculating linear regression equations made it possible to approximate the weight of the rump, shoulders, and loin based on the cold carcass weight. The results, presented in Table 6, indicate that the equations are useful and quite accurate, as the estimated and actual weights of the cuts differ by less than 0,13%. The equation used to estimate the weight of the shoulders had the smallest standard error and a high correlation coefficient. null