Simone O. Hoskin

Methanogen community structure in the rumens of farmed sheep, cattle and red deer fed different diets

Development of inhibitors and vaccines that mitigate rumen-derived methane by targeting methanogens relies on knowledge of the methanogens present. We investigated the composition of archaeal communities in the rumens of farmed sheep (Ovis aries), cattle (Bos taurus) and red deer (Cervus elaphus) using denaturing gradient gel electrophoresis (DGGE) to generate fingerprints of archaeal 16S rRNA genes. The total archaeal communities were relatively constant across species and diets, and were less variable and less diverse than bacterial communities. There were diet- and ruminant-species-based differences in archaeal community structure, but the same dominant archaea were present in all rumens. These were members of three coherent clades: species related to Methanobrevibacter ruminantium and Methanobrevibacter olleyae; species related to Methanobrevibacter gottschalkii, Methanobrevibacter thaueri and Methanobrevibacter millerae; and species of the genus Methanosphaera. Members of an archaeal group of unknown physiology, designated rumen cluster C (RCC), were also present. RCC-specific DGGE, clone library analysis and quantitative real-time PCR showed that their 16S rRNA gene sequences were very diverse and made up an average of 26.5% of the total archaea. RCC sequences were not readily detected in the DGGE patterns of total archaeal 16S rRNA genes because no single sequence type was abundant enough to form dominant bands.

Effects of reducing anthelmintic input upon growth and faecal egg and larval counts in young farmed deer grazing chicory ( Cichorium intybus ) and perennial ryegrass ( Lolium perenne )/white clover ( Trifolium repens ) pasture

A rotational grazing experiment using weaner deer was conducted at Palmerston North, New Zealand, during the autumn, winter and spring, to compare the voluntary feed intake (VFI), liveweight gain (LWG) and carcass production of deer grazing chicory with those grazing perennial ryegrass/white clover pasture. Deer were either treated with anthelmintic at 3-weekly intervals (T) or anthelmintic was withheld until trigger-treatment (TT) criteria were attained. Pure red and 0·75 red: 0·25 elk hybrid stags and hinds were given forage allowances of 5 kg DM/deer/day in autumn and early-mid winter, 6 kg DM/deer/day in late winter and 7 kg DM/deer/day in spring. Deer grazed chicory or pasture in autumn and spring, with all deer combined on pasture during winter when chicory was dormant. Organic matter digestibility of diet selected was greater for chicory than for pasture in both autumn and spring. Anthelmintic-treated deer grazing pasture in autumn had significantly higher VFI and LWG, contributing to higher carcass weights, than TT deer. Anthelmintic treatment had no effect on these measures for deer grazing chicory in autumn. Clinical signs of lungworm infection were evident in pasture TT deer during autumn and winter, and in chicory TT deer grazing pasture during winter. Faecal egg counts (FEC) were significantly greater for pasture TT deer during autumn and early winter than all other groups. Faecal lungworm larval counts (FLC) were significantly greater for chicory TT deer following transfer to pasture, than for all other groups in early winter, although both FEC and FLC were low. Faecal larval counts were poorly related to clinical signs of lungworm infection during autumn, but were a better guide in winter. Plasma pepsinogen concentrations appeared unrelated to gastrointestinal parasite infection. Trigger-treated deer grazing pasture required five anthelmintic treatments during autumn and winter. The chicory TT group required no anthelmintic treatment when grazing chicory during autumn, but required two treatments after transfer from chicory to pasture during winter. There was no effect of anthelmintic regime on VFI and LWG in spring, and LWG was greater for deer grazing chicory than those grazing pasture. Hybrid deer had greater spring LWG and carcass weights than red deer when grazing chicory, but similar LWG and carcass weights when grazing pasture. It was concluded that grazing chicory offers the potential for reducing anthelmintic use in farmed weaner deer, particularly during autumn.

Within- and between-animal variance in methane emissions in non-lactating dairy cows

Several studies on methane (CH4) emissions have focussed on selecting high and low CH4-emitting animals. One challenge faced by this work is the lack of consistency, or repeatability, in animal rankings over time. Repeatability for individual animals over time needs to be high to reliably detect high and low CH4-emitting animals. A possible explanation for the lack of repeatability is a relatively high within-animal variation in daily CH4 emissions, meaning that animals could then change their ranking when compared at different points in time. An experiment was undertaken with four non-lactating dairy cattle to assess the within- and between-animal variation in CH4 emissions over time when measured using the sulfur hexafluoride (SF6) tracer technique. Two contrasting diets were fed to the cattle at maintenance energy levels: lucerne silage (diet 1) and a cereal + lucerne + straw mixed ration diet (diet 2). Daily CH4 measurements were undertaken for 23 days on diet 1 and 30 days on diet 2. There was a significant (P < 0.001) difference between diet 1 and diet 2 in daily CH4 production, with mean (±s.e.) production of 124.3 (11.1) g CH4/day from diet 1 and 169.8 (±11.0) g CH4/day from diet 2. Lower CH4 yield (g CH4/kg dry matter intake) was recorded on diet 1 (22.8 ± 2.0) than diet 2 (32.0 ± 2.0). Cows differed significantly (P < 0.05) from one another in daily CH4 yield (diet 1: cow 1 = 19.4 ± 0.6, cow 2 = 22.2 ± 0.8, cow 3 = 23.2 ± 0.7, cow 4 = 25.4 ± 0.6; diet 2: cow 1 = 26.0 ± 0.7, cow 2 = 36.4 ± 0.7, cow 3 = 29.3 ± 0.7, cow 4 = 36.6 ± 0.7). Variances for daily CH4 yield were smaller for diet 1 (within animal = 6.91, between animals = 6.23) than for diet 2 (within animal = 10.09, between animals = 27.79). Estimates of repeatability (variation between animals/total variation) for daily CH4 yield were 47 and 73% in diet 1 and 2, respectively. Coefficients of variation in average daily CH4 emissions in this experiment ranged from 8 to 18% despite the fact that each animal received the same quantity and quality of feed each day. While further research is required, the high within-animal variability in CH4 emissions measured using the SF6 tracer technique may explain why there has been difficulty in obtaining consistent rankings in CH4 yields when animals are measured on multiple occasions. The results also suggest that the SF6 tracer technique may exaggerate apparent between animal differences in CH4 emissions.

Novel forages for growth and health in farmed deer

Abstract AIMS: This paper reviews recent research on the use of new forages in deer farming that may be useful for increasing growth in weaner deer for venison production, increasing the trace element status of deer, and for developing systems less reliant on chemical inputs, notably of anthelmintics used to control internal parasites. GROWTH: Grazing on pure swards of red clover (Trifolium pratense) or chicory (Chicorium intybus) increased weaner growth during autumn by 26-47% and during spring by 10-14%, relative to red deer (Cervus elaphus) grazed on perennial ryegrass (Lolium perenne) /white clover (Trifolium repens) pasture (0.8/0.2). Pre-weaning growth during lactation was increased by approximately 20%. These increases were due to increased rate of degradation of feed particles in the rumen, leading to higher digestibility and higher voluntary feed intakes (VFI). Red clover and chicory produce a greater proportion of their total dry matter (DM) during late summer and autumn than perennial ryegrass/white clover pastures, and are therefore better aligned with the seasonal feed requirements of deer. Grazing on the legume, sulla (Hedysarum coronarium), in autumn and spring increased the growth of weaner deer by 33% and 10%, respectively, relative to pasture-fed animals. PARASITES: Plants containing substantial concentrations of secondary compounds such as condensed tannins (CT) show promise for reducing problems caused by internal parasites. CT present in some legumes and the presence of low concentrations of both CT and sesquiterpene lactones in chicory are reviewed. Feeding sulla containing 35g CT /kg DM reduced abomasal nematode establishment and tended to reduce lungworm (Dictyocaulis eckerti) larval counts in faeces. Relative to weaner deer grazing pasture, weaner deer grazing chicory during autumn required fewer anthelmintic treatments without depressing growth rates. CT extracted from a range of legumes, and CT and sesquiterpene lactones extracted from chicory reduced the in vitro motility of both lungworm and gastrointestinal nematode larvae. The beneficial effects of CT-containing forages on the ability of young deer to manage internal parasite infections could be due to: indirect effects of CT resulting in increased amino-acid absorption, better meeting demands of the immune system; direct inhibitory effects of CT on parasite larvae and; taller plant morphology, reducing the ingestion of infective larvae. The effects of CT depend upon both their structure and concentration in the plant, which vary between growing conditions, plant varieties and species. TRACE ELEMENTS: Chicory contained higher concentrations of copper and cobalt than perennial ryegrass/white clover pasture grown on the same farm, and deer grazing chicory had higher liver concentrations of both copper and vitamin B12. These forages may contribute to maintaining adequate trace element status in deer. CONCLUSIONS: Grazing systems that include legumes and herbs such as sulla, red clover and chicory can be used to substantially increase the growth of weaner deer for venison production whilst maintaining deer health and reducing requirements for chemical inputs. For maximum plant persistence and animal responses, these plants should be grown and managed as special-purpose forages and not used in seed mixtures with perennial grasses.

Growth and carcass production of young farmed deer grazing sulla (Hedysarum coronarium), chicory (Cichorium intybus), or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture in New Zealand

Liveweight gain, voluntary feed intake, and carcass production were compared for pure red and hybrid (0.75 red: 0.25 elk) deer calves grazing sulla (Hedysarum coronarium cv. Necton), chicory (Cicho...

The effect of age on methane emissions from young, weaned red deer (Cervus elaphus) stags grazing perennial-ryegrass (Lolium perenne)-based pasture

Abstract Sheep less than 1 year of age consistently yield approximately 20% less methane than older adult sheep. This has implications for New Zealands National Inventory of Greenhouse Gas Emissions. The aim of this study was to determine if emissions from young farmed deer also increase with age. Methane emissions of 20 red deer stags grazing permanent perennial ryegrass‐based pasture were measured four times post‐weaning, at 4.5, 6.5, 9 and 11.5 months of age, using the sulphur hexafluoride technique. Methane production and methane yield increased with age (P < 0.05) and appeared lower (26%) than previous measurements from adult deer on similar pasture. The results from this study imply that total methane emissions from young deer recorded in the New Zealand greenhouse gas inventory are likely to be overestimated if values used for the inventory are based on adult methane emissions.

Degradation of forage chicory by ruminal fibrolytic bacteria.

Aims:  Determine the susceptibility of forage chicory (Cichorium intybus L.) to degradation by ruminal fibrolytic bacteria and measure the effects on cell‐wall pectic polysaccharides.

A model for study of lungworm (Dictyocaulus sp.) and gastrointestinal nematode infection in young red deer (Cervus elaphus).

A model of sub-clinical parasitism in young red deer, using concurrent trickle infections of lungworm (Dictyocaulus sp.) and mixed gastro-intestinal (GI) nematodes of deer-origin was evaluated. 20 parasite-free deer calves were artificially reared indoors from 4 days of age. A further five calves were naturally reared on pasture with their dams, treated with anthelmintic and brought indoors at 3-4 months. At 4-4.5 months of age they were individually housed and allocated to five groups (n=5). Groups were dosed 3 x per week, for 9 weeks with 0, 100 and 500, 200 and 1000 (2 groups), 400 and 2000 infective larvae of lungworm and mixed GI nematodes, respectively, cultured from deer faeces. Liveweight and voluntary feed intake measurements and faecal and blood samples were taken weekly. In the fourth week following cessation of trickle infection, deer were euthanased and lung and GI nematodes recovered. Both lungworm and GI nematode infections became patent at Week 4 of infection. Maximum group arithmetic mean faecal egg counts were 100-190 epg. Maximum group arithmetic mean faecal lungworm larval counts were 58-123 lpg. Group arithmetic mean nematode counts at slaughter ranged from 439-806 for GI nematodes and 31-73 for lungworm, respectively. Despite low nematode counts, reduced liveweight gain, voluntary feed intake and serum albumin concentration, elevated serum pepsinogen, gastrin and globulin concentrations and elevated peripheral eosinophil counts and slight haemoconcentration, but no clinical signs, were observed. The reduction in liveweight gain was related to the reduction in voluntary feed intake (r2=0.83; p<0.088). Naturally-reared deer had similar liveweight gains, voluntary feed intake and nematode counts to artificially-reared deer. Thus, methods of infection to produce concurrent sub-clinical lungworm and GI nematode burdens for study of sub-clinical parasitism in young deer have been defined.