Wether Sheep Research Articles

The nutritive value for ruminants of lupin seeds from determinate plants and their replacement of soya bean meal in diets for young growing cattle

Lupin seeds produced from two new varieties (CH304/70, CH304/73) of UK-grown autumn-sown determinate genotypes were studied for their chemical composition including fatty and amino acid contents together with the rumen degradation of nitrogen and the post-ruminal availability of undegraded nitrogen. A soya bean meal (SBM) was included in the rumen degradation work for comparison. In addition, for one variety (CH304/70), digestibility and energy values were measured using sheep and a comparison with SBM as a protein supplement for young growing bulls was made. The crude protein contents of varieties CH304/70 and 73 were 362 and 305 g kg −1 dry matter (DM), respectively, and their chemical composition was in general similar to previous reports. Rumen degradability of nitrogen (at assumed rumen outflow rate of 0.05 h −1) was higher than that of SBM (650, 610 and 550 g kg −1 feed nitrogen for CH304/70, CH304/73 and SBM, respectively) but considerably lower than most other reports largely because of much lower nitrogen solubilities. This was possibly due to the relatively coarse milling used in the present work. Increasing the proportion of CH304/70 in the diets of wether sheep from zero to 0.4 produced linear responses in the digestibility of all fractions except lipid, and led to an estimated metabolisable energy value for the lupin seeds alone of 16.9 MJ kg −1 DM. When SBM in the diets of growing bulls (liveweight ∼ 180 kg) was replaced on an isonitrogenous basis by lupin seeds no significant effect on performance was seen.

Effect of short-term propionate infusion on feed intake and blood parameters in sheep.

The hypothesis that propionate is a short-term feed intake-regulating agent was studied. Mature wether sheep were infused over 20 min with Na propionate into the mesenteric vein, while feed intake and feeding pattern were monitored over 1.5 h. Feed intake was reduced by infusions at 2 mmol/min, which were associated with marked increases in jugular as well as portal concentrations of insulin, glucose, and propionate. In a second experiment, animals were infused with 2 mmol/min Na propionate into the portal vein. No decrease in feed intake was observed, although there were similar increases in insulin, glucose, and propionate as found in mesenteric vein-infused animals. It is concluded that mesenteric propionate in high doses acts as a satiety factor. Possible explanations for the difference between site of infusion may be a different distribution of the infusate over the liver and/or the presence of propionate-sensitive receptors in the mesenteric/portal vein region. It seems unlikely that insulin concentrations are involved in inducing satiety in propionate-infused animals.

Effect of condensed tannins in Lotus corniculatus on the nutritive value of pasture for sheep

The extent to which condensed tannins (CT) in Lotus corniculatus were able to affect protein degradation and the nutritive value of pasture were evaluated at Palmerston North, New Zealand in 1992 in an indoor feeding trial with sheep and using in vitro incubations. The feeding trial involved three groups of seven young wether sheep held indoors in metabolism crates for the 32-day experimental period with one group fed freshly cut ryegrass/clover pasture (Pasture group) whilst the other two groups received a mixture of c. 37% freshly cut Lotus corniculatus and 63% pasture (dry matter (DM) basis). One of the latter groups was given twice daily oral drenches of polyethylene glycol (PEG) to bind with and remove the effects of the CT (PEG group) whilst the remaining sheep (Tannin group) were not drenched. Intakes of sheep given the mixed diets were constrained to that of the pasture group. The CT concentration in the lotus was 26·1 g/kg DM so that the mixed diets contained c. 10g CT/kg DM. Effects of CT on digestion and sheep performance were minimal. Apparent digestibility of N was lower in the Tannin group (76·4%) than PEG (79·8%) or Pasture (79·4%) sheep (P<0·001), but there were no differences in DM digestibility (75%) or wool growth from mid-side patches. Rumen ammonia and soluble protein concentrations appeared to be similar in PEG and Tannin sheep and volatile fatty acid (VFA) concentrations were similar in all groups (100 mmol/l).For incubations in vitro, several ratios of Lotus corniculatus: pasture were used to determine the effects of CT on precipitation of soluble proteins and the net yield of ammonia and gas with and without PEG. Homogenates of Lotus corniculatus leaves and pasture showed that 50% of soluble protein was precipitated by 1·3% CT in homogenate DM and there was a substantial decrease in in vitro degradation to ammonia when lotus leaf accounted for 33% or more of DM with pasture. This work emphasises the need for caution when extrapolating from in vitro to the in vivo situation and suggests that 1% CT from Lotus corniculatus may be insufficient to affect the nutritive value of fresh forages for sheep.

Effect of the β-adrenergic agonist cimaterol and dietary protein level on fat young sheep given diets containing submaintenance levels of dietary energy

AbstractThirty Suffolk cross wether sheep aged about 12 months and weighing 57 kg on average were used. They had been given previously a high energy diet to produce a fat body condition and average condition score of 3·7. Animals were allocated to an initial slaughter group (IS) or to four dietary treatment groups (UL, UH, CL and CH) based on sugar-beet feed (L) or white-fish meal (H) supplemented with chopped straw and pelleted, without (UL and UH) or with (CL and CH) the β-adrenergic agonist cimaterol, to provide an estimated 20 g (L) or 130 g (H) rumen undegradable protein per kg dry matter (DM). The sheep were offered 0·3 kg of the appropriate pelleted diet in addition to 200 to 400 g of chopped barley straw to provide proportionately 0·7 of the estimated metabolizable energy requirement for maintenance and, where appropriate, 2·5 mg cimaterol per day. Comparisons were made for the main effects of dietary protein intake and cimaterol and interactions between dietary protein and cimaterol.The animals on dietary treatments were slaughtered after 49 days. The animals exhibited variable reductions in live weight and weights of carcass and non-carcass components in comparison with the IS group and in response to restricted dietary energy intake. The only effect due to the elevated dietary protein provision was a smaller loss in live weight compared with the low protein diet. In contrast, compared with responses recorded in its absence, treatment with cimaterol resulted in significantly greater values for weights of cold carcass, cross-sectional area o/m. longissimus dorsi and weights of DM, crude protein and ash in the carcass with significantly smaller weights for raw fleece. In comparison with the IS group, significantly smaller changes due to cimaterol were recorded for the weights of carcass crude protein and ash. Cimaterol treatment significantly increased the weight loss of fat in the carcass and in the perirenal and retroperitoneal, but not omental, depots as components of fleece-free non-carcass fat which was also significantly reduced in total. Interactions suggested that losses in carcass weight and DM in the presence of cimaterol were less and gains in carcass protein and ash greater, on the high than on the low protein diet. The results suggest that under conditions of energy undernutrition cimaterol may induce smaller losses or larger gains in carcass but not non-carcass, crude protein at the expense of fat depletion in carcass and non-carcass fat depots.

Selenium Influences Tissue Levels of Selenoprotein W in Sheep1–4

Because selenium increases the levels of other selenoproteins, the influence of this element on selenoprotein W was examined in wether sheep fed either a low selenium diet (0.02 mg/kg) or the same diet supplemented with 3 mg selenium as selenite per kilogram diet. Muscle biopsies were taken initially and at 3.5, 7.0 and 10.5 wk. The sheep were killed after the last muscle biopsy and samples from nine tissues were taken. Selenoprotein W was determined in tissues by Western blots with a polyclonal antibody against a synthetic peptide based on the protein sequence of the homologous rat selenoprotein W. In supplemented sheep, muscle selenoprotein W was significantly increased over initial levels (P < 0.05) at 7 wk and afterwards, whereas in sheep consuming the low selenium diet, muscle selenoprotein W levels declined significantly (P < 0.05) after 10.5 wk. This selenoprotein was found in various amounts in all tissues examined. The highest levels of selenoprotein W were found in skeletal muscles and heart and the lowest was found in liver. Except for selenoprotein W in brain, the concentrations of selenoprotein W, selenium and glutathione peroxidase activity were significantly higher (P < 0.05) in all tissues from supplemented sheep than in those from unsupplemented sheep. The selenoprotein W levels in brains of the two groups were not significantly different. Thus, selenoprotein W levels in all tissues of sheep except the brain are sensitive to selenium status.

Studies on in situ degradation of feeds in the rumen: 1. Effect of species, bag mobility and incubation sequence on dry matter disappearance

Implicit to the newer more complex predictive models for estimating nutrient requirements for ruminants is a need for an accurate determination of feed degradation kinetics. The rumen in situ technique has been adopted as the standard method. However, recent ring tests and reviews have highlighted the need for improved standardisation of the in situ procedure. The aim of this experiment was to investigate differences between host species and to determine the effect of anchor weight and incubation sequence on dry matter (DM) disappearance of hay, soyabean meal (SBM) and fish meal (FM) in situ. Three mature rumen cannulated non-lactating cows and wether sheep fed a grass silage, barley diet (80:20, DM basis) were used. The experimental design was based on a latin square model with nine experimental periods, two major treatments and three levels of each treatment. Sheep and cow designs were run in parallel. Duplicate bags of each substrate were incubated (complete exchange) for 0, 2, 4, 8, 16, 24, 48 and 66 h and were allocated to treatment according to the latin square design. Treatment levels were: half normal, normal and twice the normal anchor weight for each species (0.5, 1 and 2 kg for cows and 75, 150 and 300 g for sheep) and three incubation sequences (i) 8, 16, 2, 4, 66, 48, 24 h; (ii) 8, 24, 66, 4, 2, 16, 48 h; (iii) 24, 4, 2, 66, 8, 48, 16 h. No species differences were observed ( P > 0.05) with overall mean losses of 55.8 and 55.6% for sheep and cows respectively. The degradation profiles of hay, SBM and FM were found to be different ( P < 0.001). Anchor weight and incubation sequence did not significantly effect ( P > 0.05) effective degradability values. Mean effective degradability (0.08 h −1 outflow) measurements for incubation sequence (i, ii and iii) were 52.9, 53.1 and 53.3% and for anchor weight (0.5 ×, 1 × and 2 × normal) were 52.9, 53.2 and 53.2%. It was concluded that mature ruminant species degrade hay, SBM and FM DM similarly and that anchor weight and the sequence of incubation has no effect on the degradability profiles of these feeds.

Plasma Levels of Energy Metabolites and Pancreatic Hormones in Relation to the Level of Intake and Intraruminal Infusions of Volatile Fatty Acids in Fed Wether Sheep

Abstract The effect of feeding level and intraruminal infusion of volatile fatty acids (VFA) on the jugular plasma concentrations of energy metabolites and insulin and glucagon was studied in wether sheep. Three animals (42 kg ± 0.5 of body weight) of the Swedish Landrace breed were fed a grass hay and barley diet (70:30 on a dry matter basis) at three levels of intake (L1, L2, L3) in a change-over design. In addition to the diet, 3 different VFA mixtures and water (control) were continuously infused into the rumen during 16 days (one mixture during 4 consecutive days). The energy content of the VFA mixtures infused was equivalent to 17% of the calculated metabolizable energy intake per day. Plasma levels of non-esterified fatty acids and citrate decreased, and plasma insulin increased with increasing energy intake. When propionate was absent from the VFA infusion mixtures, plasma citrate tended to increase with increasing energy intake. The plasma citrate levels were negatively correlated to the concentrations of glucose and insulin in plasma. The concentrations of glucose and insulin in plasma were increased by the infusion of propionate in animals fed at L3. There was a high correlation between plasma glucose and insulin. Plasma glucagon levels were not affected either by level of intake or by VFA infusions. No evidence was found to support the concept that propionate is a major regulator of insulin and glucagon secretion in fed sheep.

Production and glutathione responses to rumen-protected methionine in young sheep grazing dry pastures over summer and autumn

The aims of the experiment were to evaluate, in weaner sheep grazing dry annual pastures, the production responses and changes in blood and tissue glutathione concentrations to a methionine formulation (Lactet) protected from microbial breakdown in the rumen. Two groups of 60 weaner wether sheep, weighing 32·8 kg, were supplemented with lupin grain containing either nil (control) or 9 g Lactet per day. Lactet provided 3 g of protected methionine per day. The sheep grazed dry pastures and were rotated through 2 plots every week from December to June. After June the treatment ceased and the sheep grazed as one group until shearing in September. The sheep given Lactet grew 340 g more clean wool with a greater fibre diameter (1·2 µm) than the control sheep. Lactet supplementation increased liveweights during treatment and for 3 months following treatment. Faecal dry matter output was significantly increased by Lactet supplements and the effects were maintained in the post-treatment period, indicating that Lactet supplementation increased dry matter intake. Glutathione concentrations were significantly increased in whole blood, liver, and muscle but not in skin. Changes due to season were greater than changes due to treatment. It was concluded that glutathione in blood or tissues, although responsive at times, was not a reliable indicator of sulfur amino acid intake or status. Significant increases in total body water, protein, ash, fat, and total body energy were observed relative to the control group following Lactet supplementation. We conclude that young sheep grazing dry annual pastures in summer and autumn have the potential to respond to supplements of rumen-protected methionine even at low energy intakes from low quality pastures and show improvements in wool quality and quantity as well as liveweight and intake.

Influence of manufacturing conditions on the bioavailability of magnesium in calcined magnesites measured in vivo and in vitro

SUMMARYDietary calcined magnesite supplements of different particle sizes and temperatures of calcination were examined at Glasgow University Veterinary School in 1981. Balance experiments with wether sheep revealed that particle sizes &lt; 75, 75–150, 150–250 and 500–1000 μm diameter of a feed-grade calcined magnesite all increased urinary output of magnesium to a similar extent but the apparent magnesium availability coefficient for the 500–1000 μm diameter fraction (0·03) was significantly less than for fractions of smaller diameter (0·17–0·23) (P &lt; 0·01). A 1000–2000 μm fraction of fertilizer-grade material had an apparent availability of 0·18 but had the least effect on urinary magnesium output. Calcination temperatures of 800, 900 and 1100 °C significantly increased apparent availability (c. 0·46)compared with that for temperatures of 500 and 650 °C (c. 0·12) (P &lt; 0·01), and significantly increased urinary output of magnesium. Losses of magnesium from these supplements incubated in the rumen of cows at grass in 24 μm mesh nylon bags showed some correlations with their apparent availability and urinary magnesium output. Solubility in molar ammonium nitrate showed some good correlations with urinary magnesium output but not with magnesium availability. Supplementation of a low magnesium diet given to lactating ewes with fine particle (&lt; 75μm) calcined magnesite resulted in significantly greater increases in plasma magnesium concentration than when coarse particle material (500–1000 μm) was given (P &lt; 0·05), but magnesites calcined at 650 and 800 °C induced similar changes in plasma magnesium.

The effects of dietary nitrogen sources and levels on rumen fermentation, nutrient degradation and digestion and rumen microbial activity by wether sheep given a high level of molasses

AbstractA 4 × 4 Latin square design experiment with 3-week experimental periods was conducted with four wether sheep, each fitted with a permanent rumen cannula, to evaluate the effects of dietary protein sources and levels on fermentation and microbial activity in the rumen. Four complete diets were offered each containing (g/kg dry matter (DM)) molasses 248, grass silage 200 and barley straw 260. The control diet (C) also contained barley and soya-bean meal and the other three diets were supplemented with urea (CU), soya-bean meal (CS), and soya-bean meal and fish meal (CSF), respectively. This gave foods of similar concentrations of metabolizable energy (ME) and estimated fermentable ME (10·6 and 9·8 MJ/kg DM, respectively), but different levels (g/kg DM) of estimated effective rumen degraded dietary protein (ERDP) and digestible undegraded protein (DUP) (ERDP/DUP, 84/17, 109/17, 116/38 and 119/54 for diets C, CU, CS and CSF, respectively).No clinical symptoms of ill health in the animals due to the feeding of molasses were observed during the experiment. The average pH values of rumen liquors obtained at various sampling times post feeding for diets C, CU, CS and CSF were 6·40, 6·49, 6·62 and 6·47 (s.e.d. 0·06 P &lt; 0·05) respectively and average ammonia-nitrogen concentrations were 63, 81, 90 and 113 mg/l (s.e.d. 14·9, P &lt; 0·02) respectively. The average concentrations of total volatile fatty acids in the rumen liquor were similar across the four treatments. The molar proportions of propionate and butyrate were higher for the diet C than for the other three diets (P &lt; 0·05), while acetate was lower (P &lt; 0·05). Supplementing with true protein (P &lt; 0·05), but not with urea (P &gt; 0·05), increased the molar proportions of isobutyrate and isovalerate. Whole tract apparent digestibilities of DM and organic matter did not differ significantly across the four treatments, but neutral-detergent fibre apparent digestibility (0·677, 0·672, 0·716 and 0·728 (s.e.d. 0·017) g/kg DM for diets C, CU, CS and CSF respectively) and the proportions of hay DM that disappeared in the rumen during 24 h incubation (0·223, 0·238, 0·284 and 0·271 (s.e.d. 0·019) g/kg DM) were significantly lower for diets C and CU than CS and CSF (P &lt; 0·05). Urinary excretion of purine derivative nitrogen was similar across the four treatments. The results obtained from the present study indicate that there were no significant differences in the microbial crude protein synthesis in the rumen when a diet containing molasses was supplemented with urea or true protein. However, the supplementation of this control diet with true protein, but not with urea, did stimulate the degradation of hay DM in the rumen and the digestion of dietary fibre in the whole tract.

The effects of wilting of grass prior to ensiling on the response to bacterial inoculation. 1. Silage fermentation and nutrient utilization over three harvests

AbstractFour silages were prepared from perennial ryegrass swards at each of first (primary growth), second (first regrowth) and third (second regrowth) harvests during the 1993 growing season. At each harvest the four silages included two unwilted (without and with inoculant at 2·4 l/t) and two wilted (without and with inoculant at 24 l/t). The four silages within a single harvest, were offered as the total diet at maintenance levels to 12 wether sheep for 3 weeks to determine nutrient apparent digestibilities. They were also given to 12 lactating dairy coivs together with a concentrate supplement, in a three-period change-over study with experimental periods of 8-weeks duration, to examine dry matter (DM) apparent digestibility and utilization of nitrogen (N) and energy in the diets.Inoculation tended to improve silage fermentation with on average lower pH and ammonia-N/total-N across the three harvests, while wilting of grass prior to ensiling significantly increased silage pH fP &lt; 0·001) and ammonia-N/total-N (P &lt; 0·001). Neither inoculation nor wilting had any significant effect on mean nutrient apparent digestibilities, assessed through sheep, across the three harvests. However, at the second harvest inoculation significantly reduced apparent digestibilities of DM (P &lt; 0·001) and N (P &lt; 0·001). At this harvest, wilting also significantly decreased apparent digestibilities of DM (P&lt;0·05) and N (P &lt;0·01), but significantly increased apparent digestibilities of DM (P &lt; 0·05), energy (P &lt; 0·001) and N (F &lt; 0·05) at the third harvest. When the silages were offered as mixed diets to dairy cattle, neither inoculation nor wilting had significant effects on digestibilities of DM, N and energy at any of the three harvests, except for wilting which significantly decreased DM apparent digestibilities (P &lt; 0·05) at the second harvest. However, the mean apparent digestibilities of DM (P &lt; 0·01), N (P &lt; 0·05) and energy (P &lt; 0·01) across the three harvests were significantly lower following wilting, and N apparent digestibility (P &lt; 0·05) was significantly higher following inoculation. The calorimetric data indicated that inoculaton had no significant effects on either methane energy output or heat production. Wilting also had no significant effect on methane energy output, but significantly increased daily heat production (P&lt;0·05) at the first harvest. The efficiencies of metabolizable energy utilization for lactation (k1) were similar between the four silages at each of the first and second harvests, with the average being 0·50. The results of the present study indicated that inoculation tended to improve silage fermentation and significantly increased mean N apparent digestibility of mixed diets across the three harvests, while wilting significantly reduced mean DM, N and energy apparent digestibilities of mixed diets. Neither inoculation nor wilting had significant effects on Rvalue.

The energy and protein value of lupins for ruminants

A substantial proportion of the protein needs of highly productive ruminants in the UK is met by imported protein sources notably soya bean meal (SBM). New determinate varieties of sweet lupin (DSL) (Lupinus albus) low in alkaloids offer the potential to be a useful source of protein as agronomic conditions favour their cultivation in temperate climates where other proteinaceous legumes fail. There are at present no data on the new determinate varieties developed and under agronomic test in the UK. The objective of the work was to determine the chemical composition and the rumen degradability of nitrogen (N) of two UK varieties of lupins and to determine the digestibility and energy value of one of these varieties.The digestibility and metabolisable energy content of one new variety (CH304/70) of UK grown DSL was determined in a hay based diet using wether sheep (n = 5). The diets were offered in a 4 x 4 latin square design at foragexoncentrate ratios of 1.0, 0.9, 0.8 and 0.6 (dry matter (DM) basis) at near to the maintenance level of feeding.

The energy and protein value of lupins for ruminants

A substantial proportion of the protein needs of highly productive ruminants in the UK is met by imported protein sources notably soya bean meal (SBM). New determinate varieties of sweet lupin (DSL) (Lupinus albus) low in alkaloids offer the potential to be a useful source of protein as agronomic conditions favour their cultivation in temperate climates where other proteinaceous legumes fail. There are at present no data on the new determinate varieties developed and under agronomic test in the UK. The objective of the work was to determine the chemical composition and the rumen degradability of nitrogen (N) of two UK varieties of lupins and to determine the digestibility and energy value of one of these varieties.The digestibility and metabolisable energy content of one new variety (CH304/70) of UK grown DSL was determined in a hay based diet using wether sheep (n = 5). The diets were offered in a 4 x 4 latin square design at foragexoncentrate ratios of 1.0, 0.9, 0.8 and 0.6 (dry matter (DM) basis) at near to the maintenance level of feeding.

Stoichiometry ofin vitrofermentation of pure substrates with particular emphasis on methane production, using the cumulative gas production technique

There is a need to be able to measure the methane producing potential of a range of feedstuffs under different rumen conditions in order to predict more accurately the amount of methane produced per animal.In vitrotechniques using rumen fluid as an innoculum can be considered as models ofin vivorumen digestion and have been applied to estimate digestibility of feedstuffs. Thein vitrogas production technique (Menkeet. al., 1979) can be used successfully to estimate this but there has been limited attempts to use it to estimate the methane producing potential of feedstuffs. The objective was to assess the potential of the technique to do this.Three pure substrates, glucose (G), pectin (P) and cellulose (C) (lg) were pre-wetted in 94ml of medium D (Theodorouet. al., 1994). inoculated with strained rumen fluid (from wether sheep. 10ml) and incubated without agitation for 72h at 39°C.

Stoichiometry of in vitro fermentation of pure substrates with particular emphasis on methane production, using the cumulative gas production technique

There is a need to be able to measure the methane producing potential of a range of feedstuffs under different rumen conditions in order to predict more accurately the amount of methane produced per animal. In vitro techniques using rumen fluid as an innoculum can be considered as models of in vivo rumen digestion and have been applied to estimate digestibility of feedstuffs. The in vitro gas production technique (Menke et. al., 1979) can be used successfully to estimate this but there has been limited attempts to use it to estimate the methane producing potential of feedstuffs. The objective was to assess the potential of the technique to do this.Three pure substrates, glucose (G), pectin (P) and cellulose (C) (lg) were pre-wetted in 94ml of medium D (Theodorou et. al., 1994). inoculated with strained rumen fluid (from wether sheep. 10ml) and incubated without agitation for 72h at 39°C.

Dietary protein for young grazing sheep: Interactions with gastrointestinal parasitism

Effects of protein supplementation and of nematode control on production responses in young grazing sheep and on nematode population dynamics were assessed. Young Merino wether sheep ( n = 270) were allocated to one of three supplementation (Su) treatments and one of three regimes of nematode control (drench, Dr) in a factorial design. Each of the nine treatments was replicated three times in a randomised complete block. Animals received no supplement (SuO) or were given supplements at a level equivalent to 200 g day −1, fed three times a week. The supplements contained 25% lucerne meal with either 75% sunflower meal (Su1) or 75% formaldehyde-treated sunflower meal (Su2). Nematode control regimes were: not drenched unless survival of individual animals was threatened (DrO); drenched according to a strategic drenching programme (Dr1); treatment with a controlled-release albendazole capsule (Dr2). Infections with Haemonchus contortus were suppressed by use of closantel. Due to drought conditions and lack of pasture growth, lucerne hay was fed to all sheep from Week 14 onwards (350 g per head per day, fed twice a week). Supplementation reduced the need for ‘survival drenching’ in Dr0 sheep considerably. Live-weight gain was increased significantly by supplementation with Su1 or Su2 during the 36-week experiment. Undrenched animals given Su1 or Su2 tended to grow faster than unsupplemented animals in the Dr1 and Dr2 groups. Greasy wool production and fibre diameter were increased by supplementation and anthelmintic treatment. Faecal worm egg counts (FEC) in undrenched sheep were significantly lower for Su1 and Su2 sheep than for Su0 sheep. There were no effects of supplementation on FEC in Dr1 or Dr2 sheep. Worm burden was generally unaffected by supplementation, while the drenching treatments Dr1 and Dr2 reduced worm burden at Week 16 and to a lesser extent at Week 27. Trichostrongylus colubriformis was the predominant nematode species, with smaller numbers of Nematodirus spp., Trichostrongylus vitrinus, Trichostrongylus axei and Ostertagia circumcincta also present. It was concluded that supplementary feeding with protein meal substantially reduced production losses attributable to nematode infections in young grazing sheep. This appears to be due to an enhanced resilience of the host, rather than any major changes in development of protective immunity.

In vitrodegradation of amines by rumen micro-organisms

SUMMARYDegradation of biogenic amines was studied in rumen contents obtained from wether sheep adapted to diets with different levels of biogenic amines: high (H), low (L) and without (W), containing 7·4, 2·4 and 0 g amines/kg dry matter (DM), respectively. To 200 g of the rumen contents (RC), 2 ml of a solution containing a mixture of the biogenic amines: cadaverine (73·5 mmol/1), histamine (45·0 mmol/1), putrescine (830 mmol/1) and tyramine (123·5 mmol/1) were added, followed by a 5 h incubationin vitro. The fermentation pattern in RC derived from H and L differed from that in RC derived from W. This difference was attributed to differences in fermentative properties of silage and hay-based diets in the rumen. The addition of amines increased ammonia production, which was highest in RC from sheep adapted to silage with the highest amine content (diet H). Amines had no influence on gas production. Amine degradation occurred in all types of RC, but the extent depended on adaptation of the rumen microflora, such that 709, 54·2 and 25·3% of the added quantity in RC from H, L and W, respectively, was degraded. Generally, the breakdown of the individual amines was highest for histamine, followed by tyramine, putrescine and cadaverine. Tyramine breakdown was particularly slow in RC from diet W. These results imply that in animals adapted to grass silage with high concentrations of biogenic amines, the accumulation of amines in the rumen will be prevented by an increase in the amine-degrading capacity of the rumen microbes.

The effect of supplementing grass silage with barley on digestibility, in sacco degradability, rumen fermentation and methane production in sheep at two levels of intake

Two experiments are reported which examined the digestibility, in sacco degradability, rumen fermentation and methane production of grass silage unsupplemented or supplemented with rolled barley at three ratios and two planes of nutrition. Grass silage was given with rolled barley to four mature wether sheep using forage:concentrate (F:C) ratios of 1.00, 0.75, 0.50, and 0.25 (dry matter (DM) basis) at near to maintenance (experiment 1) and 1.5 × maintenance (experiment 2) in two consecutive latin square designs. All diets within plane of nutrition were designed to be isoenergetic and all animals received a mineral/vitamin supplement. The diets were fed for 28 d, with rumen fluid sampling on day 12. Apparent digestibility and rumen degradability (in sacco) of diet organic matter (OM) were measured and methane produced was measured in open-circuit respiration chambers for four consecutive 24 h periods. Apparent digestibility of organic matter (OMD) increased linearly (P < 0.001) in both experiments with decreasing F:C ratio (0.74, 0.79, 0.83, 0.88 and 0.72, 0.75, 0.78, 0.82 for experiments 1 and 2 respectively). Decreasing F:C ratio depressed the effective degradability of silage OM from polyester fibre bags in both experiments (quadratic effect P < 0.05) and also for barley in experiment 1 (quadratic effect P < 0.05). Rumen pH was significantly decreased with decreasing F:C ratio in both experiments as was the total mean VFA concentration. The molar proportions of acetate and propionate tended to decrease and that of butyrate increased with decreasing F:C ratio. Over the range of barley inclusion in this study there were no associative effects on methane production (1 d−1) in experiment 1 (37.2, 41.5, 41.9, 44.0 1 d−1 for F:C ratio 1.00, 0.76, 0.51 and 0.26 respectively), but the opposite was true at the higher level of intake (methane 1 d−1, 54.1, 60.1, 58.0, 50.1 for F:C ratios 1.00, 0.78, 0.54, 0.28 respectively). Rumen stoichiometry could not be used to explain the change in methane production. Increased level of intake reduced methane production (1 kg−1 organic matter apparently digested) regardless of F:C ratio. Expressing methane relative to the efficiency of digestion, or the efficiency of animal production, enables the potential for reduction of methane generation by starch supplementation and/or level of intake to be realised.

The effect of supplementing grass silage with barley on digestibility, in sacco degradability, rumen fermentation and methane production in sheep at two levels of intake

Two experiments are reported which examined the digestibility, in sacco degradability, rumen fermentation and methane production of grass silage unsupplemented or supplemented with rolled barley at three ratios and two planes of nutrition. Grass silage was given with rolled barley to four mature wether sheep using forage:concentrate (F:C) ratios of 1.00, 0.75, 0.50, and 0.25 (dry matter (DM) basis) at near to maintenance (experiment 1) and 1.5 × maintenance (experiment 2) in two consecutive latin square designs. All diets within plane of nutrition were designed to be isoenergetic and all animals received a mineral/vitamin supplement. The diets were fed for 28 d, with rumen fluid sampling on day 12. Apparent digestibility and rumen degradability (in sacco) of diet organic matter (OM) were measured and methane produced was measured in open-circuit respiration chambers for four consecutive 24 h periods. Apparent digestibility of organic matter (OMD) increased linearly ( P < 0.001) in both experiments with decreasing F:C ratio (0.74, 0.79, 0.83, 0.88 and 0.72, 0.75, 0.78, 0.82 for experiments 1 and 2 respectively). Decreasing F:C ratio depressed the effective degradability of silage OM from polyester fibre bags in both experiments (quadratic effect P < 0.05) and also for barley in experiment 1 (quadratic effect P < 0.05). Rumen pH was significantly decreased with decreasing F:C ratio in both experiments as was the total mean VFA concentration. The molar proportions of acetate and propionate tended to decrease and that of butyrate increased with decreasing F:C ratio. Over the range of barley inclusion in this study there were no associative effects on methane production (1 d −1) in experiment 1 (37.2, 41.5, 41.9, 44.0 1 d −1 for F:C ratio 1.00, 0.76, 0.51 and 0.26 respectively), but the opposite was true at the higher level of intake (methane 1 d −1, 54.1, 60.1, 58.0, 50.1 for F:C ratios 1.00, 0.78, 0.54, 0.28 respectively). Rumen stoichiometry could not be used to explain the change in methane production. Increased level of intake reduced methane production (1 kg −1 organic matter apparently digested) regardless of F:C ratio. Expressing methane relative to the efficiency of digestion, or the efficiency of animal production, enables the potential for reduction of methane generation by starch supplementation and/or level of intake to be realised.

Specification of pen rail spacing and trough heights to prevent escape and enable good access to feed by sheep during sea shipments from New Zealand

A trial was carried out to determine the optimal height of feeding troughs above floor level and the spacing between pen railings which would enable sheep to access feed troughs but prevent them from getting out of pens during sea voyages. The trial involved a group of 16 large (79 kg) wether sheep and 24 small (30 kg) wether lambs which were held in pens and trained to eat lucerne pellets. Feed troughs similar to those used on ships were constructed 260 mm deep and 220 mm wide. A system of adjustable railings were used to alter the trough height and to determine the optimal spacing to allow the large sheep to get their heads through, but to prevent small sheep from escaping. In order that sheep of various sizes can access feed from the bottom of feed troughs, the height of the top edge of the trough should not exceed 360 mm above floor level for 30 kg sheep or 460 mm for mature sheep. This range is due to differences between the groups in their shoulder height, and variation between individuals within each group. Shoulder heights of the small sheep used in this trial ranged from 505 to 590 mm, and for the 16 mature animals the range was 610-715 mm. It is important that the feed troughs are low enough for all animals to access the feed on offer. Mature sheep were able to pass their heads between rails spaced at 200 mm without difficulty, but some difficulty was experienced when the space was reduced to 180 mm. The maximum rail spacing which prevented the escape of 30 kg lambs could not be determined with certainty because they could pass through a space of only 180 mm when laid on their side, but the smallest space through which they passed voluntarily was 220 mm. Hence the optimal spacing between railings which would allow all sheep good access to feed and would prevent almost all small sheep from escaping is about 190-210 mm.