Venison and velvet production from Red and hybrid deer by one year of age : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University, New Zealand
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Date
1996
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Massey University
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Abstract
A grazing experiment was conducted at Massey University Deer Research Unit, Palmerston North, New Zealand during 1995, to study the effects of grazing chicory (Cichorium intybus), Lotus comiculatus and perennial ryegrass (Lolium perenne)lwhite clover (Trifolium repens) pasture upon the growth, voluntary feed intake (VFI), venison and velvet production of red and hybrid (0.75 red;0.25 elk) deer from weaning to slaughter at one year of age. The animals were randomly allocated to graze either chicory, lotus or pasture and grazed these forages during autumn and spring using a rotational grazing system, with each group balanced for genotype and sex. All groups were joined to graze pasture during winter, when chicory and lotus were dormant.
1. Few animals attained the target slaughter weight (50kg carcass or greater) when grazing pasture and spiker velvet antler weight was low at approximately 0.2 kg per stag.
2. In this study the greatest advantages obtained for specialist forages were for chicory. Carcass weight of deer grazing chicory was higher than for deer grazing pasture, due mainly to increasing autumn LWG and dressing-out percentage at slaughter, with a smaller response in spring LWG. The largest carcass weights were consistently obtained from hybrid stags grazing on chicory, with values for red deer and hybrid stags being 56.0 and 59.3 kg when grazed on chicory and 48.6 and 53.3 kg respectively when grazed on pasture. Chicory had a higher organic matter digestibility (OMO) and VFI than pasture during autumn but similar values in spring, accounting for its autumn
growth stimulation. Carcass subcutaneous fat depth (GR) was higher for deer grazing chicory than pasture, but after being adjusted to equal carcass weight, there was no difference in GR measurement.
Relative to deer grazing on pasture, grazing on chicory increased total spiker velvet antler production (323 v 225 g/stag), by advancing the dates of pedicle initiation (18 days), velvet antler initiation (24 days), and first velvet cutting (17 days) and increasing the rate of velvet antler length growth. Initiation of velvet growth was correlated with liveweight, with each 10 kg increase in liveweight advancing the dates of pedicle initiation, commencement of velvet growth and first velvet cutting by 10, 18 and 13 days respectively. Correction of the data to equal liveweight removed a component of the advancement produced from feeding on chicory, but an effect still remained due to chicory feeding per se. It was concluded that grazing chicory not only increased carcass weight (especially in hybrid stags), but also increased velvet antler production. This was achieved by increased VFI and increased OMO of chicory in autumn, relative to deer grazing pasture, and probably by increased absorption of protein and minerals in deer fed chicory.
3. OMO of lotus was higher than that of pasture during autumn, but not in spring. The OMO of either chicory or lotus showed little change between seasons, but pasture changed with the season, being of lowest OMO in autumn and highest OMO in spring.
4. Responses to deer grazing lotus were limited by the reduced number of grazing days that could be achieved, due to problems in lotus establishment. In spite of these problems, grazing lotus (48 gCT/kg OM) did increase the LWG of stags during autumn (248 v 176 g/day) and increased the efficiency of growth in spring, with LWG being similar to deer grazing pasture, but VFI being lower (1.53 v 2.00 kgOM/day) for lotus compared to pasture. Although deer grazing lotus had a similar carcass weight compared to deer grazing pasture, dressing-out percentages of deer grazing lotus were higher than that of deer grazing pasture (56.4 v 53.2 %). The carcass GR tissue depth of deer
grazing lotus had similar values compared to pasture. There was no interaction between forage and genotype for carcass weight and dressing out percentage. Stags grazing lotus did not show any advancement in dates of pedicle initiation, velvet antler initiation and weight of velvet production compared to stags grazing pasture.
5. Total condensed tannin (CT) concentration in lotus was 48 and 13 g/kgOM in hand plucked and oesophageal fistulae (OF) extrusa samples respectively. Most CT in hand plucked lotus samples was extractable, with much smaller amounts being protein-bound or fibre-bound. Extractable CT was not detected in lotus OF extrusa samples, and the concentration of protein-bound and fibre-bound CT remained similar to hand plucked samples. Therefore, after chewing during eating, the extractable component of CT in lotus feed could not be extracted and detected by the Butanol/HCI analysis methods and may have been bound to deer salivary proteins. Total CT in both hand plucked and OF extrusa samples was 3.1 v 5.8 g/kgOM for chicory and 0.3 v
1.5 g/kgOM for pasture. As a result, chewing (in OF samples) did not reduce the CT content of pasture or chicory. This may be due to the low concentration of extractable CT (and high proportions of bound CT) in these forages, which may have limited access for the deer salivary CT-binding proteins.
6. Overall it was concluded that chicory was of very high feeding value (FV) and had excellent nutritional advantages for increasing deer production. However, crops of chicory need to have specialised grazing management to increase persistency. New chicory cultivars need to be selected to increase persistency and to reduce reproductive stem formation during summer. Effects of protein supply on initiation of pedicle and velvet antler development in weaner stags grazing fresh forages also needs to be studied.
The small responses obtained in the present study give some indication that the CT content of Lotus comiculatus may have a number of values for improving the efficiency of growth in young deer. Further experiments are needed in this area.
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Keywords
Feeding feeds, Deer, New Zealand, Venison, Carcasses