Effects of immunocastration and amino acid supplementation on fallow deer testicle development

Thoniso Chitambala

Master's thesis

Abstract:

Forty-four fallow deer (Dama dama) bucks (10 months of age; 22.9 ± 2.4 kg) were allocated to one of four treatment combinations (n = 11 per treatment) to investigate the combined effects of immunocastration vs intact male production under different nutrition, namely supplemented with an oat-wheat based diet either with or without rumen-protected amino acids (Lysine and Methionine at a ratio of 3:1). Improvac® (2 mL per dose) was administered to the immunocastrated bucks at weeks 1, 8 and 20 of the study, and the study concluded at week 39. At slaughter, testicles were harvested immediately, weighed, and sperm were recovered from the cauda epididymis. Smears were prepared to determine viability, testicle surface CIELab colour was measured, and testicle tissue samples were taken for histological assessment of seminiferous tubule development. To assess the relationship between testicle development, secondary sexual traits, and dimorphic body development, linear body measurements were taken, internal fat deposits were assessed, and antler size parameters were determined. The animals with a greater degree of testicle development had larger body sizes, greater forequarter development, and antler development. Immunocastration influenced testicle development, as evident in testicle surface colour (increased L values, i.e., lighter testicles), decreased the sperm viability, and seminiferous tubule size. On the contrary, amino acid supplementation increased a colour values (i.e., redder testicles) and increased sperm viability. Intact males fed amino acids showed the greatest seminiferous tubule development. Thus, immunocastration may be a viable welfare-friendly alternative to physical castration in deer culled from the herd for venison production to suppress testicle development and functioning, while amino acid supplementation shows potential for improving the development of yearling fallow deer bucks selected for breeding.

Keywords

castration, Dama dama, nutrition, sperm, venison, welfare

Language used: English

Date on which the thesis was submitted / produced: 25. 4. 2023

Thesis defence

• Date of defence: 30. 5. 2023
• Supervisor: Tersia Needham, Ph.D.
• Reader: Katarzyna Tajchman, externi

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / specializace:
Wildlife and Livestock Production, Management and Conservation / Sustainable Animal Production