Farmed-raised fallow deer (Dama dama L.) carcass characteristics and meat nutritional value

Study of Processing Conditions during Enzymatic Hydrolysis of Deer By-Product Tallow for Targeted Changes at the Molecular Level and Properties of Modified Fats

In most cases, the unused by-products of venison, including deer tallow, are disposed of in rendering plants. Deer tallow contains essential fatty acids and can be used to prepare products for everyday food and advanced applications. This work aimed to process deer tallow into hydrolyzed products using microbial lipases. A Taguchi design with three process factors at three levels was used to optimize the processing: amount of water (8, 16, 24%), amount of enzyme (2, 4, 6%), and reaction time (2, 4, 6 h). The conversion of the tallow to hydrolyzed products was expressed by the degree of hydrolysis. The oxidative stability of the prepared products was determined by the peroxide value and the free fatty acids by the acid value; further, color change, textural properties (hardness, spreadability, stickiness, and adhesiveness), and changes at the molecular level were observed by Fourier transform infrared spectroscopy (FTIR). The degree of hydrolysis was 11.8-49.6%; the peroxide value ranged from 12.3 to 29.5 µval/g, and the color change of the samples expressed by the change in the total color difference (∆E*) was 1.9-13.5. The conditions of enzymatic hydrolysis strongly influenced the textural properties: hardness 25-50 N, spreadability 20-40 N/s, and stickiness < 0.06 N. FTIR showed that there are changes at the molecular level manifested by a decrease in ester bonds. Enzymatically hydrolyzed deer tallow is suitable for preparing cosmetics and pharmaceutical matrices.

Seasonal Variation in the Body Composition, Carcass Composition, and Offal Quality in the Wild Fallow Deer (Dama dama L.)

The goal of this study was to examine the seasonal variation in the body composition, carcass composition, and quality of edible internal organs from the fallow deer hunt-harvested in the summer (n = 9) and the winter (n = 10) seasons. The weight and proportion of the mesenteric and omental fat were greater for the animals harvested in the winter (1.12 kg and 2.75%) compared to those from the summer season (0.43 kg and 1.02%). The winter-harvested animals had more perinephric fat (0.75 kg and 1.84%) than those hunted in summer (0.26 kg and 1.84%). The gastrointestinal tract of the fallow deer hunted in summer was more filled with feed and therefore heavier (7.92 kg) compared to those from the winter season (5.16 kg). The proportion of fat was significantly greater in the carcasses obtained in winter compared to the summer season (6.55% vs. 3.79%). No seasonal variety was found in the physicochemical characteristics of the edible offal, but the content of extractable fat was significantly affected by the season. In conclusion, the effect of the season on the slaughter value of the hunt-harvested fallow deer was limited to a variation in the proportion of some of the internal organs and affected the fat deposition in the body of the examined animals. The season significantly affected the fat content in the carcass and the extractable fat content in the examined offal.

Assessment of the Role of Free-living and Farmed Fallow Deer (Dama dama) as A Potential Source of Human Infection with Multiple-Drug-Resistant Strains of Yersinia enterocolitica and Yersinia pseudotuberculosis

Yersinia enterocolitica and Y. pseudotuberculosis are Gram-negative, facultative anaerobic bacteria that cause yersiniosis—one of the most important zoonotic diseases of the digestive tract. The aim of this study was to determine the prevalence of potentially human-pathogenic Y. enterocolitica and Y. pseudotuberculosis strains in free-living and farmed fallow deer, and to evaluate their sensitivity to chemotherapeutics. A total of 372 rectal swabs were analyzed, including 262 from free-living and 110 from farmed fallow deer. Due to the psychrophilic properties of Yersinia, two samples were collected from each animal. Seven Y. enterocolitica strains were isolated from free-living fallow deer, while two strains were isolated from farmed fallow deer. Yersinia pseudotuberculosis strains were not identified. All isolated Y. enterocolitica strains were ystB-positive, and phylogenetic analysis based on the nucleotide sequences of this gene revealed the presence of two phylogenetic groups. Yersinia enterocolitica strains isolated from fallow deer belonged to biotype 1A, and serotyping analysis demonstrated that the vast majority did not agglutinate with any diagnostic sera. All strains were multiple drug resistant and were not sensitive to at least four of the tested chemotherapeutics (amoxicillin with clavulanic acid, ampicillin, cefalexin, and streptomycin). One Y. enterocolitica strain isolated from a free-living animal was resistant to nine out of the 13 analyzed chemotherapeutics and was intermediately sensitive to the four remaining chemotherapeutics. The highest sensitivity was noted in case of ciprofloxacin (five strains) and trimethoprim-sulfamethoxazole (three strains). Only one strain isolated from a free-living animal was sensitive to three out of the 13 examined antibiotics, whereas the remaining strains were sensitive to only one drug or were not sensitive to any of the chemotherapeutics used. The results of this study indicate that multiple drug-resistant Y. enterocolitica strains can be carried by free-living and farmed fallow deer. This observation gives serious cause for concern because the meat of fallow deer and other ruminants is often consumed semi-raw (steak) or raw (tartar steak).

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

Effect of Sex and Age on Nutritional Content in Wild Axis Deer (Axis axis Erx.) Meat

Simple Summary

Game meat is perceived as more nutritious than meat originating from domestic farm-ranged animal species. However, meat composition is affected by numerous factors, and differences between game species can be found. The aim of this study is to examine the effect of sex and age on the content of macro- and micro-nutrients in meat from axis deer. Sixteen animals were hunt-harvested and assigned to groups according to sex and age. Samples of m. longissumus thoracis were examined to determine proximate chemical, fatty acid, amino acid and mineral composition. Minor differences were found in the analysed traits between sex and age groups. Regardless of sex and age, axis deer meat is characterised as having a high protein and low-fat content, favourable fatty acid composition and ratios. It is a good source of essential amino acids and micro-minerals. As data regarding axis deer meat are limited, the results of this study are a valuable contribution to describing the quality and nutritional composition of meat of different deer species. Axis deer meat can be recommended as a healthier substitute to red meat.

Abstract

The aim of this study is to examine the effect of sex and age on proximate chemical, fatty acid, amino acid and mineral content of axis deer (Axis axis Erx.) meat. Sixteen (n = 16) animals were hunt-harvested and assigned to groups according sex and age (sub-adult and adult). All analyses were made on m. longissimus thoracis sampled between the 9th and 13th ribs. Minor differences in nutritional composition of axis deer meat were found between analysed sex and age groups. Axis deer meat has a high protein (22.8%) and low fat (1.39%) content. Saturated fatty acids accounted for 44.97% and polyunsaturated for 29.66% of the total fatty acids. Ratios of fatty acids were within the recommended values. Glutamic and aspartic acid were the most abundant non-essential, and lysine and leucine the most common essential amino acids. The ratio of essential to non-essential amino acids was <1. Potassium and phosphorous were the dominant macro-minerals, while iron and zinc were the dominant micro-minerals. The results of this study show that regardless of sex or age, axis deer meat can be considered a good source of basic macro- and micro-nutrients, and can be recommended as a substitute for red meat from domestic animals.