Wether Lambs Research Articles

Rumen fermentation and digesta passage in ruminants fed cimaterol

In Experiment 1, rumen fluid samples were collected from 12 Finnish Landrace crossbred wether lambs following slaughter after a 64 day experimental period during which they were offered a pelleted concentrate ration ad libitum. Cimaterol was included in the concentrate ration at 0 or 10 mg kg −1. Neither ammonia and volatile fatty acid (VFA) concentrations, nor acetate, propionate or butyrate proportions of VFA were affected by dietary cimaterol inclusion. In Experiment 2, eight ruminally fistulated Friesian steers were fed either 0 or 0.09 mg cimaterol kg −1 body weight (BW) in a ration consisting of 340 g concentrate and 660 g hay kg −1 dry matter (DM). The allowance of 15.5 g DM kg −1 BW was fed in two equal portions daily for 35 days. Rumen fluid samples were collected immediately before the first feed and 2, 4, 8, 12, 16 and 24 h thereafter on two occasions. Rumen liquid and solid turnover were measured by ruminal pulse dosing with cobalt-EDTA and ytterbium-labelled hay, respectively. Dietary inclusion of cimaterol did not affect rumen fluid pH and concentrations of ammonia or VFA in rumen fluid, but increased the acetate and propionate proportions of VFA and decreased the butyrate proportion of VFA, particularly after the second daily feed. These effects resulted in significant alterations in the acetate to propionate and non-glucogenic ( acetate + 2- butyrate propionate ) ratio. Dietary inclusion of cimaterol did not affect rumen liquid or solid digesta turnover. It was concluded that cimaterol had a small but beneficial effect for growth on the concentration of measured end-products of ruminal metabolism, but had no effect on digesta passage from the rumen.

Comparative Performance of Castrated Male Lambs from two Crossing-Sire Breeds

Finished lamb production in the UK is based upon the use of terminal sire breeds, selected for carcass characteristics, mated to crossbred ewes, chosen for maternal attributes. Previous experiments have shown that even where good quality terminal sires were used too high a proportion of finished lambs produced carcasses of moderate quality (Merrell, Webster and Ellis 1990; Merrell 1993). Ultimately, an improvement in the carcass attributes of crossbred ewes should help to alleviate this problem. A long term experiment which aims to compare the performance of crossbred ewes bred from two crossing-sire breeds was set up in 1989. During the first phase of this experiment (1989 - 1992) selected ewe lambs were retained to produce the two crossbred ewe flocks, surplus ewe lambs and all wether (castrated male) lambs were finished. Data are presented for finished wether lambs produced during this initial phase.

Multiple Ovulation and Embryo Transfer in Hill Ewes

A breed improvement programme has been initiated at both ADAS Redesdale (Scottish Blackface) and ADAS Pwllpeiran (Welsh Mountain) to improve carcass conformation of hill ewes. From a base population of 1100 Welsh Mountain and 1600 Scottish Blackface ewes, nucleus flocks of 60 ewes have been established. Selection of ewes into the nucleus flock at each site has been based on their ability to consistently produce wether lambs crops with good conformation and above average carcass weights when selected for slaughter at a fat class 2/3L. The next objective is to replicate these ewes through multiple ovulation and embryo transfer (MOET) since theoretical studies (Smith, 1986) indicate that this can substantially increase the rates of genetic improvement through the female line. However, to date little work has been conducted to determine whether this technology can be successfully applied to hill sheep maintained in harsh hill environments in the UK, and this formed the basis of the current study.

Beans (vicia faba) as a finishing supplement for hill lambs under organic management

Silage finishing systems have been developed for store lambs, the type and level of supplement required depending on the quality of forage available (Butler, 1985). Under the requirements laid down by the United Kingdom Register of Organic Food Standards (UKROFS), restrictions are made on both the total quantity of concentrates and the protein source fed. While some work has been carried out on alternative sources of protein in the diets of finishing lambs (Yilala and Bryant, 1985), little informantion is available on the use of beans under UK conditions.The objective of this experiment was to assess the potential of beans as an alternative protein source for lambs fed to UKROFS standards on a basal ration of baled silage.One hundred and forty four approximately six month old Scottish Blackface wether lambs (mean liveweight 33.6 kg, se = 0.23) were housed off silage aftermaths. Following an acclimatisation period of twelve days, these were randomly allocated in pens of 12 to one of four treatment groups depending on the type of concentrate fed - beans (B), 50/50 barley/beans (BB), barley/soya (BS) and barley/fishmeal (BF). A mineralised supplement of 400 g of concentrate was fed daily in each case. Moderate quality baled silage (dry matter (DM) 307 g/kg, metabolisable energy 9.4 MJ/kg DM, crude protein 129 g/kg DM) was available to appetite, with fresh material offered twice daily. The barley component of the rations was rolled: beans were fed whole.

Corn supplementation of lambs grazing alfalfa.

We investigated the effects of supplementing Rambouillet x Suffolk wether lambs grazing irrigated 'Cimarron' alfalfa (Medicago sativa L.) with three levels (0 [C0], 123 [C123], and 247 [C247] g of DM.lamb-1.d-1) of cracked corn. Each treatment group also received 190 g of a supplement designed to prevent bloat. Replicated pastures (three per treatment) grown on a fine, mixed, thermic Torretic Paleustoll soil were grazed rotationally (forage plus supplement allowance of 6.5% of BW/d) by lambs for 85 d during spring 1992. Supplemental corn levels were analyzed as single degree of freedom contrasts for linear and quadratic effects. At the start of the experiment, lambs weighed 30.7 +/- .32 kg. Average daily gains for C0 C123, and C247 were 141, 154, and 169 g/d, respectively. Lamb production per hectare increased quadratically (P < .01) with increasing corn level (C0 [716 kg of lamb/ha], C123 [816 kg of lamb/ha], and C247 [964 kg of lamb/ha]). Supplementation with C247 vs C0 increased carcass weights (11%), dressing percentage (6%), and backfat thickness (30%). Plasma urea N (PUN) concentrations did not differ (P > .10) between C0 and C123 after 27 d of corn supplementation, but after 75 d PUN concentrations between C0 and C123 had decreased (P < .10) by 11%. For C247, PUN concentrations after 27 and 75 d of corn supplementation had decreased (P < .10) by 17 and 18%, respectively, compared with C0. Plasma urea N concentrations increased (P < .01) linearly (r2 = .93) with an increase in digestible CP:DE ratio (DP:DE).(ABSTRACT TRUNCATED AT 250 WORDS)

Finishing Performance of Hill Lambs Fed Clover-Rich Baled Silage to Ukrofs Standards

Within conventional silage finishing systems, forage quality is critical to lamb performance and some concentrate feeding is generally required (Fitzgerald, 1987). Rate of finish may also be manipulated by increasing the concentrate component of the diet, particularly in the latter stages of the finishing period. For organic production however, the United Kingdom Register of Organic Food Standards (UKROFS) limit concentrate supplementation to 40% of daily dry matter intake, and a flatter pattern of concentrate allocation is generally required. Where diets containing a high proportion of clover (more likely under an organic or low nitrogen system) are fed, improvements in lamb performance have been shown in grazing animals (Clark, 1988) and following ensiling (Vipond et al, 1992). The aim of this experiment was to assess the potential of high clover silage to finish hill lambs from the organic unit at ADAS Redesdale.One hundred and forty four approximately six month old Scottish Blackface wether lambs (mean liveweight 30.0 kg, se = 0.24) were housed off silage aftermath and assigned (in pens of twelve) to one of three treatments - grass silage plus 400 g concentrate (GH), high clover silage plus 400 g concentrate (CH) or high clover silage plus 200 g of mineralised barley (CL).

The Response of Finishing lambs to Additional Metabolisable Energy Supplied from Either Silage or Concentrate

Increased lamb production during the 1980's stimulated interest in winter indoor finishing systems, traditionally all-concentrate. Recent research has been directed towards the supplementation of a silage-based ration as an option to reduce costs. The objective of this experiment is to compare the utilisation of metabolisable energy (ME) from silage and concentrate for carcass gain and to determine the effect of ME source on carcass quality.Seventy-eight Blackface wether lambs (mean initial live weight 29.3 kg) were housed in late October and offered silage for two weeks prior to allocation to treatments.

Nitrogen and energy metabolism and serum constituents in lambs given broiler poultry litter processed by three deep-stacking methods

AbstractPoultry litter has been used as an economical nitrogen (N) source in ruminant diets. However, litter must be processed to eliminate pathogens. Broiler poultry litter was processed by three different deep-stack methods: (1) uncovered, (2) covered with 0.1524 mm clear polyethylene, and (3) aerated by placing perforated pipe 1 m apart within the stack. Stack temperature was measured for 28 days. The litter was used to formulate experimental diets (186 g litter per kg), while the control diet contained urea as the N source. All diets contained 100 g/kg cottonseed hulls, 16 to 17 g/kg limestone, varying amounts of cracked maize and added retinol. The control diet contained 131 g/kg crude protein (CP) while the litter diets contained 125 g/kg CP. The diets were offered to 16 crossbred wether lambs (37 (s.e. 6·1) kg) in individual metabolism crates for 16 days. Blood was collected at the initiation and termination of the trial. Covering litter with plastic decreased temperature ivithin the stack (P &lt; 0·05). Maximum temperature for the uncovered, covered and aerated stacks was: 68°C, 57°C and 72°C, respectively. Dry-matter intake and dry matter, energy and neutral-detergent fibre apparent digestibilities were not different (P &gt; 0·05) among the diets. Apparent digestibility for N was less (P &lt; 0·05) in lambs given uncovered and aerated litter than in those given the control diet. However, N apparent digestibility in lambs given covered litter was not different from that of those given the control diet. Gross energy and N retention of the four diets were not different (P &gt; 0·05). Covering deep-stacked broiler poultry litter improved N digestibility by proportionately 0·15 compared with uncovered litter. Serum chloride was decreased while serum urea was increased (P &lt; 0·05) in sheep consuming the litter-containing diets. Deep-stacked broiler litter should be covered in an air-tight manner in order to maximize its nutritive value.

Effects of substituting feather meal for soybean meal on ruminal fiber fermentation and lamb and wool growth.

Our objective was to evaluate the effects of substituting feather meal (FM) for soybean meal (SBM) on ruminal fiber fermentation, lamb gain, blood metabolite profiles, and wool growth. A SBM supplement was formulated, and FM replaced either 33% (33FM), 66% (66FM), or 100% (FMS) of the SBM protein. Four ruminally cannulated wethers were used in a 4 x 4 Latin square design to study in situ ruminal digestion. Wethers were limit-fed barley straw and fed the supplements once daily. Ruminal NH3 N concentrations reflected a sampling time x protein source interaction (P < .01). Within sampling times, ruminal NH3 N concentrations decreased linearly (P < .05) as FM replaced soybean meal. Cubic (0 h; P < .10) and quadratic (24 h; P < .05) responses also were noted for ruminal NH3 N concentration. Substitution of FM for SBM had no effect (P > .10) on rate and extent of straw NDF disappearance. A 56-d feeding trial was conducted using 28 wether lambs (n = 7 per treatment; initial BW 32.3 kg). Wethers were individually fed chopped barley straw and one of the four supplements described previously. Linear increases (P < .05) in BW gain and serum total protein concentration were observed as FM replaced SBM. Wool fiber diameter and sulfur content did not differ (P > .10) among treatments. These data suggest that FM can be substituted for SBM in protein supplements fed to sheep consuming low-quality roughages at a maintenance level of ME intake.

Exogenous growth hormone releasing factors and cottonseed meal improve growth performance and composition of gain in lambs fed lucerne chaff ad libitum

Forty-eight crossbred wether lambs (38 kg) were randomly assigned to two dietary groups (LUC, chaffed lucerne ad libitum; CSM, LUC plus 300 g cottonseed meal/lday) and two hormone treatment groups (rGRF, recombinant growth hormone-releasing factor (GRF); sGRF, synthetic GRF) plus controls (CON, excipient only), and slaughtered after treatment for 28 (n = 36) or 30 (n = 12) days. An initial slaughter group (n = 12) was killed on day 0. CSM reduced intake of lucerne chaff, but increased total feed intake. CSM also increased liveweight gain and wool growth, with no effect on feed conversion efficiency. CSM increased carcass weight and decreased subcutaneous fat depth, with no effect on dressing percentage or longissimus dorsi (LD) area. Meat tenderness tended to decrease with CSM supplementation. CSM increased carcass protein accretion ( P &lt; 0.01), with no significant change in fat gain or final composition (P &gt; 0.05). CSM increased weights of the pelt, liver and empty body, and decreased the proportion of digesta in liveweight. Weights of blood, forestomachs and small intestine tended to increase as well (P &lt; 0.10). Both sources of GRF had similar effects. Intakes were not significantly affected by GRF, but feed conversion efficiency improved (P &lt; 0.01) with GRF treatment (6.4 v. 9.2 feed:gain for GRF and CON respectively). Liveweight gains and final weights of the whole body and carcass were increased additively by CSM and GRF. GRF reduced fat depth and increased LD area, with no effect on dressing percentage, carcass length or meat tenderness. These changes reflected increased carcass protein and reduced fat contents, brought about by increased accretion of protein and water and reduced fat gain due to GRF. GRF increased weights of blood and liver beyond the general increase in body size. Cottonseed meal and GRF additively produced significant improvements in growth performance and carcass quality of young wether lambs fed a roughage diet. GRF may be a useful tool to improve livestock production under extensive and intensive conditions.

Relative bioavailability of copper in a copperlysine complex for chicks and lambs

Two experiments were conducted to study the relative bioavailability of Cu in a Cu-lysine complex with that of reagent grade CuSO 4·5H 2O for chicks and lambs. Chicks were fed a basal diet (11 mg kg −1 Cu, dry matter (DM) basis) or the basal diet supplemented with 150, 300 or 450 mg kg −1 Cu from either of the two Cu sources for 18 days. Birds were killed and liver Cu concentrations determined. Liver biopsy samples were collected from wether lambs who were then fed the basal diet (9.5 mg kg −1 Cu DM) or the basal diet supplemented with 60, 120 or 180 mg kg −1 Cu from either source for 10 days. Copper in the initial biopsy was used as a covariate in the multiple linear regression of log 10 final liver Cu concentration on added dietary Cu concentration. Slope ratio comparisons gave relative Cu bioavailability values of 99 and 68 for Cu-lysine in chicks and lambs, respectively, compared with 100 for CuSO 4·5H 2O for both species.

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Getting back to normal

Intramuscular collagen characteristics of ram, wether, and zeranol-implanted ram lambs.

Eighteen spring-born Columbia ram, wether, and zeranol-implanted ram lambs were studied to determine the influence of castration or zeranol implants on intramuscular collagen (IMC) properties and muscle shear force values. Warner-Bratzler shear force values for longissimus muscle were greatest for ram lambs, intermediate for implanted rams, and least for wethers (P < .05). Nonreducible collagen crosslink concentration was greater in IMC of rams and implanted rams (P < .05). The IMC from rams compared with that from wethers contained proportionately more Type III than Type I collagen (P < .05); values for implanted rams were intermediate. Heat-soluble muscle collagen concentration was greater for rams and implanted rams than for wethers (P < .05); however, insoluble collagen concentration did not differ by treatment. Muscle collagen concentrations were not different for rams, wethers, or implanted rams. Increased shear force values in rams were associated with elevated collagen crosslink concentration and increased proportion of Type III collagen. Greater concentration of soluble collagen in ram IMC neither diminished nor diluted IMC crosslinking. The proportion of heat-labile collagen in the fractions did not reflect the IMC crosslinking profile for ram and wether lambs. Zeranol implantation modified IMC characteristics of rams such that shear force values and some collagen properties were similar to those of wethers.

Assessment of protein quality in heat-treated soybean products using the growth responses of lambs and calves and a nylon bag-rooster assay2

Three studies were conducted to evaluate N and amino acid (AA) availability from processed soybean (SB) products. In Exp. 1 and 2, treatments consisted of corn-cottonseed hull basal diets plus SB products including SB meal (SBM); ground, raw SB (RSB); or extruded SB (ESB). In Exp. 1, 15 Suffolk (28.6 kg) and 15 Louisiana native breed (16.3 kg) ewe lambs were used in a 35-d growth trial. Although breed affected (P < .10) DMI and ADG of lambs, the diets did not (P > .10). In Exp. 2, 12 Suffolk wether lambs (34.0 kg) were used in a 3 x 3 multiple-square Latin square design N metabolism trial. Lambs fed RSB tended (P = .13) to retain more N than those fed ESB, but N retained by lambs fed RSB and ESB was similar (P > .10) to that of lambs fed SBM. In Exp. 3, four crossbred steer calves (240 kg) were used in a 4 x 4 Latin square design N metabolism trial with the above treatments plus heat-damaged SB (HDSB). Calves fed RSB and ESB retained similar (P > .10) amounts of N. Compared with calves fed RSB and ESB, calves fed SBM retained more (P < .10) N. Calves fed HDSB retained less (P < .10) N than those fed other diets. The individual SB products and the total mixed diets used in Exp. 3 were incubated intraruminally in nylon bags and the residual DM recovered and precision-fed to cecectomized roosters to estimate its intestinal AA digestibility. Digestibility of residual AA seemed to be relatively uniform across AA.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific activity of pentose cycle oxidative enzymes during feeder lamb development

Relationships between pentose cycle oxidative activity and differential fat growth were evaluated. Rambouillet wether lambs (n = 60) were slaughtered serially at 0, 40, 80, and 120 d on feed (15 lambs/group). Rack dissection and kidney fat weights were collected, and longissimus muscle i.m. fat content was determined. Postmortem longissimus muscle, s.c. fat, intermuscular fat (INT), and kidney fat (KP) samples were assayed in vitro for glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activity (nanomoles.minute-1.gram of tissue-1), and samples were subjected to electrophoresis (PAGE) to separate tissue-specific isoforms. Allometric coefficients for rack components indicated that s.c. fat was the earliest-maturing, slowest-growing depot, INT was the latest-maturing, fastest-growing depot, and i.m. fat was intermediate (P < .05). Kidney fat grew faster than carcass weight and, as carcass weight increased, the growth rate of KP accelerated (P < .05). Enzyme activities increased until 40 d on feed and declined thereafter. Activities differed across tissues and time on feed end points (P < .05). Ratios of G6PDH:6PGDH, reflecting flux through the oxidative phase of the pentose cycle and, therefore, lipogenic activity, suggested growth patterns similar to those indicated by allometric analysis, except in the i.m. fat depot. Development of i.m. fat initially was intermediate to KP and INT, but G6PDH:6PGDH ratios increased with time on feed, suggesting a different regulatory mechanism and maturing pattern. Multiple forms of G6PDH were detected with PAGE, and although polymorphism was not detected, a tissue-specific isoform was isolated for INT fat.

Protein, acetate and propionate for roughage-fed lambs. 2. Nutrient kinetics

AbstractThirty-six wether lambs were given food hourly consisting of mature chopped oaten hay, sprayed with 10 g urea per kg hay. A pelleted supplement was given containing 0 or 75 g/day fish meal and 0 or ca. 1·5 MJ/day gross energy as acetate or propionate in a 2 × 3 factorial design. Dry matter (DM) digestibility, nitrogen retention and urinary allantoin excretion were determined over 7 days. Tissue protein kinetics were estimated using15N-glycine. Net fluxes of acetate, bicarbonate and glucose were estimated with continuous infusion of14C-acetate,14C-bicarbonate and3H-glucose respectively.Intake of oaten hay (g DM per kg live weight per day) was reduced by supplementation. Live-weight gain was lower in lambs supplemented with propionate than in lambs given the basal diet only. Supplementation with fish meal increased DM digestibility, live-weight gain and wool growth. Daily excretion of urinary allantoin did not differ between groups of lambs. Nitrogen retention and protein flux were reduced in lambs supplemented with acetate or propionate and were increased in lambs given fish meal. Plasma acetate concentrations were higher for lambs supplemented with acetate. However, net flux of acetate did not differ between groups of lambs. The net flux of glucose was increased by supplementation with propionate and with fish meal. Plasma levels of β-hydroxybutyrate were reduced in lambs supplemented with propionate.Availability of propionate and glucose were not limiting live-weight gain in these lambs. Also, a high ratio of acetate to propionate did not reduce the apparent efficiency of nutrient use.

The influence of an inoculant/enzyme preparation as an additive for grass silage offered in combination with three levels of concentrate supplementation on performance of lactating dairy cows

AbstractThree silages were prepared from the primary growth of a predominantly perennial ryegrass sward (dry matter (DM) 175 g/kg; crude protein 142 g/kg DM; water-soluble carbohydrates (WSC) 243 g/kg DM). Herbage was wilted for 24 h and then treated with either an inoculant/enzyme preparation (Lactobacillus plantarum, Streptococcus faecium and Pediococcus acidilactici), formic acid applied at 4·2 lit (Add F, BP Chemicals) or no additive. Time series analysis of laboratory silages revealed that different patterns of fermentation had been achieved: formic acid treatment resulted in high levels of residual WSC and low levels of lactic acid, indicative of an inhibited fermentation, whilst treatment with the inoculant/enzyme preparation resulted in high levels of lactic acid with a low level of residual sugars, as expected with an enhanced fermentation. Analysis of the material ‘as fed’ showed that losses in the WSC content of the formic acid-treated silage had occurred in the clamp. Secondary fermentation of lactic to acetic acid was apparent in the untreated silage, but not in the inoculant/enzyme-treated silage. Digestibility, as determined using Greyface wether lambs, was marginally higher for both additive treatments when compared with the untreated silage. An evaluation of the silages for milk production was carried out at three levels of concentrate supplementation using 18 Ayrshire × British Friesian cows in a replicated 3×3 Latin-square design experiment. Treatment with formic acid resulted in significantly higher DM intakes, but this was not reflected in milk energy output. Cows offered the inoculant/enzyme-treated silage partitioned energy away from milk production toward body tissue deposition (average milk yields 19·9, 19·9 and 15·2 kg/day, and weight gain 0·26, 0·38 and 0·81 kg/day for the untreated, formic acid and inoculant/enzyme-treated silages respectively). The reason for this is not clear, but it is postulated that microbial capture of degraded nitrogen may have been impaired with the inoculant/enzyme-treated silage, resulting in an imbalance in metabolizable protein: metabolizable energy.

Diet selection in sheep: the ability of growing lambs to select a diet that meets their crude protein (nitrogen × 6.25) requirements

To test the proposition that sheep are able to select a diet that meets their crude protein (N x 6.25; CP) requirements, feeds L, A, B, C and H with the same energy content (11 MJ metabolizable energy/kg feed) but different CP contents (78, 109, 141, 172 and 235 g CP/kg fresh feed respectively) were formulated. In addition, feed U, which was feed L plus 21.4 g urea/kg (CP content 132 g/kg), was also made. The feeds were offered ad lib. either singly (n 4 per treatment) or as a choice between feed H and another feed (pairs LH, AH, BH, CH and UH; n 9 per feed pair) to individually penned Suffolk x Scottish mule wether lambs, over the live-weight range 25-45 kg. On the single feeds the rates of live-weight gain were 273, 326, 412, 418, 396 and 407 g/day (SE of difference (SED) 34; P < 0.01) and protein (excluding wool) gain were 27, 32, 44, 45, 41 and 39 g/d (SED 4; P < 0.001) for feeds L, A, B, C, H and U respectively. When sheep were given a choice between a feed below (L or A) and a feed above their CP requirements (H; as judged by the single-feeding treatments) the CP concentration selected was not different between the two pairs: 131 (SE 4) v. 133 (SE 4) g CP/kg feed for pairs LH and AH respectively. On the choices BH and CH (a choice between two feeds above requirements) the feed lower in CP was constantly preferred (874 (SE 33) and 910 (SE 33) g feed B and C respectively per kg total feed intake; CP selected was 157 and 178 g CP/kg respectively). However, this was not the case with the UH choice on which sheep consumed only 599 (SE 61) g feed U/kg total feed intake, resulting in a selection of a higher CP in their diet (173 g CP/kg). The live-weight gains of the animals given a choice between two feeds were 416, 387, 415, 410 and 383 g/d (SED 37) and protein gains were 45, 40, 46, 50 and 43 (SE 7) for pairs LH, AH, BH, CH and UH respectively, which were comparable with the best performance achieved on a single feed. The results suggest that sheep were able to select a diet that meets their CP requirements and avoid, at least to a certain extent, excess of protein intake.(ABSTRACT TRUNCATED AT 400 WORDS)

Grazing trials with sheep on kikuyu(Pennisetum clandestinumChiov.) foggage in the eastern Transvaal highveld

Abstract Sheep performance and patterns of herbage utilization were determined in two grazing trials involving different amounts and quality of kikuyu foggage. In both trials each paddock of a series of paddocks of each foggage type was grazed successively. Amounts of leaf and stem, and the digestible organic matter and crude protein contents of these components, were determined at the start and end of grazing in each paddock. In one trial, wether lambs maintained livemass whereas, in the other, dry ewes and wether lambs both lost 8–10% of their initial mass, irrespective of differences in foggage quality. Grazing capacity was proportional to the yield of foggage. Although the percentage leaf in the foggage in the different treatments varied from 72 to 89, only some 50% of the total herbage was utilized. The estimates of quality indicated that a higher level of utilization would have resulted in poorer sheep performance.

Confinement of lambs ( Ovis aries) in metabolism stalls increased adrenal function, thyroxine and motivation for movement

Eighteen, 8-week-old Rambouillet wether lambs were habituated to human contact for 2 months prior to data collection. The lambs were maintained in a paddock prior to being placed in individual 41 cm × 95 cm metabolism stalls for 9 days. Blood samples were taken via jugular cannulae 7 days prior to, and after 2 and 9 days of confinement. After two basal blood samples were drawn, 1 iu kg −1 adrenocorticotrophic hormone (ACTH) was administered to each lamb via the cannulae and serial blood samples were drawn over the next 3 h. A 5-min open-field test was conducted the day before the lambs were placed in stalls and again after Day 9, following the last blood sampling. Response to ACTH, measured as the integrated cortisol concentrations, was greater when the lambs were housed in stalls than maintained in the paddock ( P < 0.01). Confinement did not affect plasma concentrations of triiodothyronine ( P < 0.37), but lambs in stalls had higher concentrations of thyroxine after 2 and 9 days than when on pasture ( P < 0.001). Lambs traveled further during the open-field tests, after 9 days in the metabolism stalls, than they did before confinement ( P < 0.001). These results indicate that lambs maintained in metabolism stalls can be physiologically and behaviorally altered. Such alterations may affect the applicability of certain types of data derived from these lambs compared with lambs in more extensive housing situations.