Differential effects of ruminally protected amino acids on fattening of fallow deer in two culling periods

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.

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.

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.

Potential benefits of amino acid supplementation for cervid performance and nutritional ecology, with special focus on lysine and methionine: A review

Deer farming is a thriving industry for venison, velvet antlers, trophy hunting, and other by-products. Feeding and nutrition are important factors for improving production performance, especially dietary protein and amino acids (AAs), as they are the main components of all tissues. Only a few studies on AA supplementation (Lys, Met, Arg) have been performed on cervids, which show positive effects on weight gain, ADG, feed-:gain ratio, plasma AAs, carcass weight, dressing percentage, yield of high-quality muscles, storage of internal fat during winter, DM and CP digestibility, plasma protein- and fat-related metabolite concentrations, antler burr perimeter, weight, length and mineralisation, velvet antler yield, rumen volatile fatty acids, and microbiome composition. All these effects are relevant for supporting the production of cervids products, from venison to velvet or trophy antlers, as well as their general performance and well-being of captive-bred cervids. The current available information suggests that AA supplementation can be especially interesting for animals fed low protein rations, and growing animals, but should be avoided in high rations and during winter, since it may promote the accumulation of internal fat. Potential effects on milk production and the concentrations of different hormones involved in the regulation of the antler cycle should be further explored.