The Effect of Barley and Lysine Supplementation of Pasture-Based Diet on Growth, Carcass Composition and Physical Quality Attributes of Meat from Farmed Fallow Deer (Dama dama)

Effects of Immunocastration and Amino Acid Supplementation on Yearling Fallow Deer (Dama dama) Testes Development

Forty-four fallow deer bucks (10 months old; 22.9 ± 2.4 kg) were utilized to investigate the effects of immunocastration and amino acid supplementation on testes development. Immunocastrated bucks were administered Improvac® at weeks 1, 8, and 20 of this study (control group: intact males). Starting at week 8, half of each sex received rumen-protected lysine and methionine (3:1) supplementation. At slaughter (week 37/39), body size, internal fat deposits, antler size parameters, testes weight, testes surface color, cauda epididymal sperm viability and morphology, and seminiferous tubule circumference and epithelium thickness were determined. Animals with larger body sizes, greater forequarter development, and antler growth also had greater testes development. Whilst the result of immunocastration on testes size is unexpected, testes tissue showed impaired development (atrophied seminiferous tubules), decreased sperm viability, and normal morphology. Testes tissue from immunocastrated deer was less red, possibly indicating reduced blood supply. Conversely, amino acid supplementation increased testes' redness and sperm viability, and intact males fed amino acids showed the greatest seminiferous tubule development. Thus, immunocastration may be a welfare-friendly alternative for venison production. Whilst the results support findings from the literature that testes size is not a reliable indicator of immunocastration success, this warrants further investigation in deer over different physiological development stages.

Effects of immunocastration and supplementary feeding level on the performance and blood biochemical markers of farmed yearling fallow deer (Dama dama)

In cervids, blood biochemical markers may reflect changes in various physiological and environmental factors, especially in response to changes in metabolism following nutrient supplementation or the manipulation of hormone production. Decreasing androgen production through immunocastration (IC) to ease the husbandry of male animals is currently a more ethically acceptable method than physical castration, but its commercial use is unexplored in fallow deer. Forty yearlings male fallow deer were grouped into four treatment combinations: IC on high (200 g commercial pellets + 600 g concentrate mixture of 90% oats and 10% wheat grains) or low (100 g commercial pellets + 300 g concentrate mixture of 90% oats and 10% wheat grains) level of feed supplementation, or noncastrated bucks on a high or low level of feed supplementation. Immunocastrated animals were vaccinated at the start of the study (Week 1) and again during Week 3 of the study. Diet affected all body growth parameters (slaughter weight, daily gain, carcass weight, dressing percentage and body condition score). Fallow deer from all treatments showed increasing concentrations of fat and energy blood biochemical markers over the study period, including plasma glucose (GLU) and triglyceride (TRIG), and decreased cholesterol (CHOL) and lipase (LIPA) concentrations. The higher level of supplementary feeding decreased plasma albumin (ALB) and creatinine (CREA), and increased globulin (GLOB) concentrations. On the other hand, IC and lower-level supplementation reduced growth performance. Overall, IC may be an interesting tool for welfare management of yearling stags for slaughter; however, the advantage appears to only be in well-fed animals, as low-level of feeding can further reduce growth performance in immunocastrated animals. Further studies should evaluate the carcass performance of animals under similar treatment conditions to ascertain the effects on muscle and fat yields.

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 and Offal Yields of Farmed Common Eland (Taurotragus oryx) Males, as Affected by Age and Immunocastration

This study investigated the effects of immunocastration and slaughter age on the carcass yield performance of intensively farmed common eland males. Eighteen male eland (five immunocastrated juveniles, three intact juveniles, five immunocastrated sub-adults, and five intact sub-adults) were finished for four months, after which their carcass, offal, primal cut, and individual muscle yields were determined. Juveniles were ~6 months of age at the start of the experiment, while sub-adults were ~1.5 years old. Primal cuts were dissected to determine the percentage yields of meat, bones (with tendons), separable fat, and trimmings. Immunocastration had no effect on offal or carcass yields. While sub-adults had increased individual muscle yields, juveniles had greater proportionate yields of primal cuts and a greater total high-value: low-value meat ratio. Whilst slaughtering younger male eland could provide additional economic advantages, this should be considered being against changing marketing trends.

Effects of Dietary Barley Starch Contents on the Performance, Nutrient Digestion, Rumen Fermentation, and Bacterial Community of Fattening Hu Sheep

The objective of this experiment was to investigate the effects of substituting corn starch (CS) with barley starch (BS) on the growth performance, nutrient digestion, rumen fermentation, and bacterial community of fattening Hu sheep. Seventy-two Hu lambs with similar initial body weight (BW, 29.70 ± 1.70 kg) were randomly assigned to four treatments, with 18 lambs per group. The four experimental diets have identical starch contents but with different starch sources as 100% starch from corn (BS-0), 33% starch from barley and 67% starch from corn (BS-33), 67% starch form barley and 33% starch from corn (BS-67), and 100% starch from barley (BS-100). All lambs were reared in individual units and fed high-concentrate diets (85% concentrate in diets based on dry matter [DM]). The experimental period included 7 days for adaptation and 63 days for data collection. Sixteen ruminal cannulated Hu sheep were divided into 4 groups and received the four experimental diets to determine the dynamics of ruminal pH. The average daily gain (ADG), and BW gain of lambs linearly decreased (p < 0.05), whereas the feed to gain ratio linearly increased (p < 0.05) with increasing dietary proportions of BS. Digestibility of DM, organic matter, neutral detergent fiber, acid detergent fiber, starch, and gross energy (GE) decreased (p < 0.05) with increasing dietary BS contents. Ruminal mean pH decreased (p < 0.05) with increasing proportions of dietary BS, accompanied with linearly increased (p < 0.05) time and area of ruminal pH below 5.80 or 5.60. Increasing dietary proportions of BS linearly decreased (p < 0.05) the molar proportion of acetate, but linearly increased (p < 0.05) the molar proportion of propionate. Sheep of the BS-0 and BS-33 treatments had a less (p < 0.05) relative abundance of Selenomonas ruminantium than that of sheep of the BS-67 treatment, but a greater (p < 0.05) relative abundance of Ruminococcus albus than that of sheep of the BS-100 treatment (p < 0.05). In conclusion, feeding a high-concentrate corn-based diet for fattening Hu sheep improved the performance and rumen fermentation parameters when compared to the barley-based diet.

The Effect of Barley and Lysine Supplementation on the longissimus lumborum Meat Quality of Pasture-Raised Fallow Deer (Dama dama)

The chemical characteristics (proximate composition, amino acids, and fatty acids) and sensory quality of the longissimus lumborum (LL) muscle of 45 farmed male fallow deer were investigated. The animals were divided into three separate groups (n = 15 per treatment): pasture-fed (P), pasture-fed and supplemented with barley (B), and pasture-fed and supplemented with barley and lysine (BL). Differences were observed in LL moisture and the intramuscular fat contents, the latter being almost two-fold greater in the meat of B and BL groups compared to P. The concentrations of histidine, leucine, alanine, glutamic acid and glycine in the raw meat were higher in the BL group compared to the P group. Higher contents of n–3 polyunsaturated fatty acids (PUFAs), and consequently lower n–3 ratios, were found in the P group, compared to the BL group. The grilled meat samples from the P group scored higher than the other groups for grassy flavour, and lower for liver flavour.

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

This study analysed carcass features and the chemical composition of semimembranosus (SM) and longissimus thoracis et lumborum (LTL) muscles from farmed-raised fallow deer (Dama dama L.) bucks (n = 8). Mineral contents and fatty acid composition were also determined in the muscles and the fulfilment of the demand for minerals was calculated for adults. Dressing percentage was 55.2%, whereas the proportions of round, shoulder and loin were 38.4%, 15.5% and 14.4%, respectively. The highest content of meat tissue was found in round, followed by loin. There were no differences in moisture, fat, protein or ash contents between SM and LTL muscles, however differences in mineral contents and fatty acid composition were noted and affected the concentration of nutrients. Meat from farmed-raised fallow deer is a good source of iron and copper in the human diet and may be recommended as a part of a healthy diet.