Grass Pellets Research Articles

Intake and utilization of energy from ammonia-treated and untreated wheat straw by steers and wether sheep given a basal diet of grass pellets and hay

AbstractTwo experiments, experiment 1 with six steers in a 3 × 3 Latin-square design and experiment 2 with four wether sheep in a cross-over design, were conducted to study the effect of species and ammonia treatment on intake and utilization of the energy of untreated wheat straw. Treatments were: (1) untreated wheat straw offered ad libitum on top of a basal diet (B) consisting of hay (0·25) and grass pellets (0·75) (UWS), (2) ammoniated wheat straw offered ad libitum plus B (AWS) and (3) ammoniated wheat straw offered at a restricted level plus B (AWS-). B was offered as a maintenance diet for both species and AWS- was only studied in steers. Voluntary intake of AWS zvas higher than that of UWS. No significant differences emerged between whole rations UWS and AWS with regard to energy digestion (ED), energy metabolizability (ρ = metabolizable energy (ME) I gross energy (GE)) and losses of digestible energy (DE) in urine and methane (average 187 J/KJ DE), but the efficiency of utilization of ME for growth (kg) was significantly higher for AWS than for UWS. ED and ρ of the straw part of the ration was significantly higher for AWS than for UWS. AWS- and AWS did not differ significantly with regard to ED, ρ and DE losses in methane and urine. Steers had a higher intake per kg0·75 per day than wether sheep. Across species, digestible energy intake (DEI) of the whole ad libitum fed diets was related to live weight (M)0·946 (s.e. of exponent 0·0152). ED and ρ of the straw part of the rations did not differ significantly between species, but steers had a significantly higher ED and ρ of β than wether sheep. Steers excreted a significantly lower proportion of DE in urine and a significantly higher proportion of DE in methane than did wethers. Total energy losses in urine and methane, however, did not differ between species.

Accretion of total protein and individual amino acids by organs and tissues of growing lambs and the ability of nitrogen balance techniques to quantitate protein retention

AbstractTwelve Suffolk-Finn Dorset lambs were reared from 25 to 40 or 25 to 55 kg body weight on either pelleted dried grass or a ration of pelleted grass plus barley (ratio 1:1) in a comparative slaughter experiment designed to determine the amounts of total nitrogen and individual amino acids accreted in different body components during growth. Nitrogen (N) balance measurements were determined frequently during this growth phase and accumulated N retentions were compared with the total N accretion determined by comparative slaughter. Total N and individual amino acids accumulated in carcass, wool, skin, offal and blood, head and feet, gastro-intestinal tract and liver were linearly related to body weight in all cases other than for cysteine in carcass. At 25 kg live weight, proportionately 0·52 of total body N was in carcass components, 0·115 in wool, 0·08 in skin, 0·10 in offal and blood, 0·095 in head and feet, 0·06 in the gastro-intestinal tract and 0·02 in liver. However as the animals grew from 25 to 55 kg, 0·256 of the total N accretion was in wool, which was rich in cysteine (98 g/kg total amino acid). Carcass accretion represented only 0·449 of total body N accretion. The N balance technique overestimated net protein accretion by 0·24 (s.e. 0·036).

137Cs Transfer After Chernobyl from Fodder Into Chicken Meat and Eggs

The distribution and the biological half-lives of 137Cs in poultry after continuous intake of foodstuffs contaminated by the Chernobyl fallout were studied in order to determine transfer coefficients to yolk, albumen, and shell of eggs as well as transfer coefficients to chicken meat. Mean values for laying hens were found to be 0.2 d kg-1 (whole consumable egg), 1.2 d kg-1 (leg meat), and 1.6 d kg-1 (breast meat) when radiocesium was fed in contaminated grass pellets, and about twice as large [i.e., 0.4 d kg-1 (whole consumable egg), 2.8 d kg-1 (leg meat), and 3.0 d kg-1 (breast meat)] when radiocesium was fed in contaminated wheat. Reducing effects of the feed additive ammonium-ferric-cyano-ferrate in concentrations of 0.66 g kg-1 of feed mixture on the contamination of hen products were quantified to be a factor of 3 to 4 (whole consumable egg and meat after grass pellet feeding) and 8 to 14 (whole consumable egg and meat after wheat feeding). A drastically higher reduction with an ammonium-ferric-cyano-ferrate dose twice as large (1.33 g kg-1) was achieved. For broiler chickens, activity concentration ratios of meat to feed were derived for various fattening periods, with mean values of about 0.3 (leg), 0.4 (breast), and 0.2 (liver). The addition of ammonium-ferric-cyano-ferrate reduced the activity concentrations in meat by factors of more than 6.

Effects of levels of food intake and body condition on the sensitivity of the hypothalamus and pituitary to ovarian steroid feedback in ovariectomized ewes

ABSTRACTIn two experiments involving ovariectomized Scottish Blackface ewes and steroid replacement therapy, the effects of level of food intake and of body condition on hypothalamic and pituitary sensitivity to progesterone and oestradiol feedback were investigated. In experiment 1, groups of 16 ewes in similar levels of body condition were given dried grass pellets ad libitum (mean dry-matter (DM) intake of 2481 (s.e. 71) g per head per day; group H) or 1105 g DM per head per day (group M). In experiment 2, groups of 16 ewes were fed so that they achieved body condition scores of 2·70 (s.e. 0040; group HBC) or 1·67 (s.e. 0·036; group LBC) prior to the start of the experiment. All ewes were then fed to maintain their respective levels of body condition. In both experiments, all ewes were ovariectomized and intravaginal progesterone pessaries and subcutaneous oestradiol implants were inserted; these were designed to induce circulating concentrations of these steroids within the normal range for intact ewes. Approximately 1 week later, blood samples were collected at 15-min intervals for 10 h, and at 10-min intervals for 8 h before and after pessary withdrawal respectively. All samples were assayed for LH and selected samples were assayed for FSH and progesterone. Gonadotropin profiles were also recorded during 2-h periods following injection (i.v.) of 0·25 μg and 5 μg GnRH. When circulating progesterone concentrations were elevated, due to the presence of a progesterone pessary, there was no effect of level of food intake on mean LH or FSH concentrations or mean LH pulse frequency but H ewes had a higher mean LH pulse amplitude than M ewes (P < 005). When the progesterone pessaries were absent, H ewes had a higher mean LH concentration (P < 001), mean LH pulse frequency (P < 001) and LH pulse amplitude (P < 0·01) than M ewes but mean FSH concentrations were similar in the two groups. Irrespective of the presence or absence of elevated progesterone concentrations, the pituitary responses to GnRH injection were either not significantly different or were lower in H compared with M ewes. In experiment 2, HBC ewes had a higher mean LH concentration (P < 001), LH pulse frequency (P < 0·001), pulse amplitude (P < 0·001) and FSH concentration (P < 001) than LBC ewes, irrespective of circulating progesterone concentrations. The mean heights and ‘areas’ of the LH peak induced by injection of 0·25 μg GnRH were larger in HBC than LBC ewes (P < 005) irrespective of circulating progesterone concentrations. When mean concentrations before injection were taken into account, the corresponding increases in FSH concentration were similar for the two groups. Following injection of 5 u.g GnRH, the differences in peak size were generally not significant. It is concluded that during the follicular phase of the cycle, a low level of intake is associated with increased hypothalamic sensitivity, but not pituitary sensitivity to oestradiol feedback. Body condition affects both hypothalamic and pituitary activity but the relative importance of direct and indirect effects of body condition on the sensitivity of these organs to steroid feedback, remains to be elucidated.

Oral chloramphenicol in dwarf goats-influence of vasopressin on its absorption and effect of diet on its biodegradation in ruminal fluid samples

The biodegradation of chloramphenicol was studied by incubating the drug (at concentrations of 72, 48 and 24 micrograms/ml) with ruminal fluid samples from dwarf goats fed two different diets. Biodegradation of the drug was much faster in samples from animals which were fed with hay and concentrate than in those obtained from goats which were fed grass pellets only. Recently, it has been suggested that lysine-vasopressin injected intravenously induces closure of the oesophageal groove in cattle and goats. Therefore, the influence of lysine-vasopressin on the oral absorption of chloramphenicol (50 mg/kg body wt) was studied in dwarf goats, using two formulations of chloramphenicol. The results suggest that vasopressin failed to induce this reflex mechanism. Furthermore, the shapes of the plasma concentration-time curves after oral administration of chloramphenicol palmitate and chloramphenicol dissolved in propylene glycol were markedly different. Possible mechanisms for the observed differences are discussed.

Influence of duodenal digesta composition on abomasal outflow, motility and small intestinal transit time in sheep.

1. A study was made of the influence of duodenal infusion of some of the components of the digesta on gastrointestinal motility, abomasal outflow and small intestinal transit time in seven sheep fed 1500 g grass pellets/day. Gastrointestinal motility was recorded by electromyography. Abomasal outflow was estimated according to the rate of dilution of CrEDTA injected and sampled via an abomasal catheter. Small intestinal transit time was measured by the passage of Phenol Red from the duodenum to the terminal ileum. 2. Abomasal outflow was inhibited during 3 h infusions (5 ml/min) of 100 mM-acetic, propionic, butyric and lactic acids, of 50 mM-HCl, of 0.56 M-glucose, and of 2 and 4% protein hydrolysate. Abomasal motility was inhibited by these infusions and by infusion of 234 mM-oleic acid (0.75 ml/min), of a fat emulsion (Intralipid 20% 0.3 ml/min) and of 50 mM-L-tryptophan (7.5 ml/min). 3. Abomasal motility and, where tested, abomasal outflow, were not affected by duodenal infusion of 150 mM-NaHCO3 (5-10 ml/min), 0.28 M-NaC1 (5-7.5 ml/min), distilled water (5-7.5 ml/min), 25 mM-L-tyrosine (5 ml/min), and of 50 mM-acetic, propionic, butyric and lactic acids (5 ml/min). 4. At concentrations or rates of infusion above the threshold dose needed to inhibit abomasal motility, small intestinal motility was altered and the frequency and amplitude of the reticulo-ruminal contractions were inhibited. 5. The transit time through the small intestine was increased during infusion of 100 mM-acetic, propionic, butyric and lactic acids and decreased during infusion of 0.56 M-glucose and Intralipid. 6. Inhibition of abomasal motility and outflow in sheep receiving 1500 g/day grass pellets was calculated to require increases in the duodenal concentration of volatile fatty acids of about 150% and K+ of about 38%, and to require an increase in the rate of delivery to the duodenum of H+ of about 90%, nitrogen of about 22% glucose of about 2000% and fat of about 84%. 7. These findings are discussed in relation to the composition of abomasal and duodenal digesta in sheep fed different diets. 8. It seems likely that components of duodenal chyme, such as H+, volatile fatty acids, glucose and fat only affect abomasal outflow in sheep fed high-grain diets (glucose, volatile fatty acids), or diets highly supplemented with fat (fat), for short periods after meal feeding (volatile fatty acids) or under abnormal conditions (H+).(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of level of food intake on hypothalamo-pituitary sensitivity to ovarian Steroid feedback in ewes

Effects of level of food intake and body condition on ewe hormone status, ovulation rate and reproductive performance may be mediated either through a direct effect on hypothalamic or pituitary activity or through an indirect effect on the sensitivity of either or both of these organs to steroid feedback. The aim of this experiment was to determine the effect of level of food intake of ewes on hypothalamic activity and pituitary responsiveness to gonadotrophin-releasing hormone (GnRH) in the presence of ovarian steroids. Sensitivity to steroid feedback cannot be measured in an entire animal, owing to the variable and irregular nature of ovarian steroid secretion. Ovariectomised ewes were therefore used together with steroid replacement therapy.Two groups of 16 ewes were fed to achieve body condition scores of either 2.00 or 2.25/2.50 by 3 weeks before the period of study. Thereafter, ewes of the lower condition score were fed dried grass pellets ad libitum and 250 g hay/head/day (H) while those of the higher condition score were fed 1050 g pellets and 250 g hay/head/day (M), a ration designed to maintain liveweight and condition score so that at the time of study, ewes of the two groups had a similar level of body condition but different levels of intake.

The action of the beta-agonist clenbuterol on protein and energy metabolism in fattening wether lambs.

1. Five Greyface wethers (42-45 kg) fed on various fixed amounts of dried grass pellets (either approximately 1.3 times maintenance or 2 times maintenance) by means of belt-type continuous feeders were housed in open-circuit respiration chambers for periods of 45 d. Between days 15 and 35 they received daily oral doses of 1.5 mg of the beta-adrenergic agonist clenbuterol (adsorbed on to the feed). Continuous energy and nitrogen balance measurements each of 5 d duration were conducted throughout the chamber confinement. 2. On six occasions (twice during the 15 d pre-clenbuterol period, on days +4, +11 and +18 of clenbuterol administration and once during the post-treatment period) animals were infused with [1-14C]leucine to determine the rates of leucine oxidation and the amounts of leucine available for protein synthesis. 3. Clenbuterol administration caused a marked increase in N retention (2-3 g N/d; P less than 0.001) throughout the 20 d treatment period. It also increased (P less than 0.001) the energy expenditure of the animals (on average by 1.1 MJ/d over the first 5 d, compared with immediate pretreatment values, and 0.6 MJ/d over the 20 d period, compared with the mean of pre- and post-treatment control values). The effect of treatment was calculated to result, on average, in the daily retention of 19 (SE 1.5) g more protein and 30 (SE 5.5) g less fat. 4. During clenbuterol treatment leucine oxidation was reduced (P less than 0.01). However, values for the amounts of leucine available for protein synthesis were equivocal, with an increase (P less than 0.001) on day 11 of treatment, but no change on days 4 and 18. 5. Withdrawal of the clenbuterol resulted in rapid alterations of N and energy metabolism towards those expected of control animals of that weight.

Effect of level of food intake at mating on the reproductive performance of ewes passively immunized against testosterone

AbstractIn a 2 × 2 × 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of two levels of body condition (high: condition scores ^2·75; low: condition scores ^2·50) by 2 weeks before joining with rams. Half of the ewes of each condition score were fed dried grass pellets ad libitum and 300 g hay per head daily, between 2 weeks before and 8 days after joining, while the remaining ewes were offered a live-weight maintenance ration comprising 750 g pellets and 400 g hay per head daily. From 8 days after joining the intake of all ewes was gradually changed, over a 2-week period, to 1250 g pellets and 400 g hay per head daily. Two days before joining, half of the ewes of each condition/intake group were passively immunized against testosterone. A total of 99 ewes were slaughtered 18 days after joining and their ovulation rate at the first mating determined. Ovulation rates were significantly affected by immunization (immunized: 2·31, control: 1·86, pooled s.e. = 0·055; P < 0·01) and food intake (ad libitum: 2·24, maintenance: I 92, pooled s.e. = 0·055; P < 0·05) but not by body condition at mating (high: 2·15, low: 2·02, pooled s.e. = 0·059; P > 0·05). Lambing rates were dependent on treatment (immunized: 1·82 control: 1·62, pooled s.e. = 0·044; P < 0·01), food intake (ad libitum: 1·85, maintenance: 1·59, pooled s.e. = 0·043; P < 0·01) and body condition (high: 1·82, low: 1·62, pooled s.e. = 0·044; P < 001). In ewes in a high body condition at mating, the effects of intake and immunization were additive but in ewes in low condition, immunization induced little improvement in performance in ewes fed ad libitum. Circulating antibody titres were lower in ewes fed ad libitum than in ewes offered a maintenance ration (1: 416 v. 1: 534, pooled s.e. = 14; P < 0·001), but ovulation rates and litter sizes were not related to titres.

The effects of feeding either hay or grass diets on salivary phosphorus secretion, net intestinal phosphorus absorption and on the partition of phosphorus excretion between urine and faeces in the sheep.

Mature sheep fitted with ruminal and duodenal cannulas were fed either a pelleted hay or a pelleted grass diet with or without supplementary phosphorus. Salivary phosphorus secretion, net intestinal phosphorus absorption and the route of phosphorus excretion were determined. The route of excretion was markedly affected by diet with urinary excretion being much higher and faecal excretion lower when the grass diet was fed. These effects were not due to differences in phosphorus intake or to differences in net intestinal phosphorus absorption. Salivary phosphorus secretion was, however, lower when the grass diet was fed. The significance of these changes in relation to the control of phosphorus balance in ruminants is discussed.

Effect of level of food intake on the reproductive performance of ewes in different levels of body condition at mating, following passive immunisation against testosterone

In a 2 x 2 x 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of 2 levels of body condition (high : C.S. ⩾ 2.75; low : C.S. ⩽ 2.50). Half of the ewes of each condition group were then fed dried grass pellets ad libitum with 300 g hay/ head/day (high intake); the remainder were fed a liveweight maintenance ration of 750 g pellets and 400 g hay/head/day (low intake) between 14 days before and 8 days after joining. Thereafter, feed levels for both groups were gradually adjusted to 1250 g pellets and 400 g hay/head/day which was fed until mid pregnancy after which they were fed according to foetal load. Mean daily inatkes of dried grass pellets for ewes fed ad libitum were 2.45 and 2.27 kg fresh weight/head/day for ewes in the low and high condition groups respectively. The patterns of liveweight and condition score changes associated with these feeding regimes are summarised in Table 1.

Inhibition of reticulo-ruminal motility by volatile fatty acids and lactic acid in sheep.

1. A study was made of the influence on reticulo-ruminal motility, recorded by electromyography, of ruminal infusions of volatile fatty acids (VFAs) and lactic acid in twenty-four sheep maintained by intragastric infusion of a complete liquid diet, in three sheep fed grass pellets, and in nine chronically vagotomized sheep; abomasal and duodenal infusions of VFA and lactic acid were tested in five sheep fed grass pellets. 2. Ruminal infusions of VFAs and lactic acid progressively inhibited the amplitude of the reticulo-ruminal contractions. In many experiments there was no effect on contraction frequency until the cessation of all reticulo-ruminal contractions at which point the maximal concentration of VFA recorded in the abomasum was 28 mM, and that of lactic acid was 20 mM. 3. The concentrations of undissociated VFAs causing cessation of reticulo-ruminal contractions in the vagus-intact sheep were very similar to the concentrations causing abolition of the organized intrinsic motility of the chronically vagotomized sheep. 4. The inhibition of reticulo-ruminal motility with ruminal infusions of mixtures of VFAs and of lactic acid together with VFAs could largely be explained by the sum of the effects of the individual acids present. 5. Abomasal infusion of VFA or lactic acid inhibited the amplitude of ruminal, especially primary ruminal, contractions at concentrations of undissociated acid of 60 mM and above and increased the frequency of reticulum and primary ruminal contractions at about 80 mM. 6. Duodenal infusion of VFAs and lactic acid (100 mM, 5 ml/min) strongly inhibited abomasal motility without affecting reticulo-ruminal motility, and at a higher rate (100 mM, 10 ml/min) abolished motility and inhibited both the amplitude and frequency of reticulo-ruminal contractions. 7. It is concluded that the initial inhibition of reticulo-ruminal motility in ruminal acidosis is unlikely to involve any significant influence from duodenal, or abomasal receptors. The final cessation of reticulo-ruminal motility with ruminal acidosis could involve local effects of VFAs in the reticulo-rumen as well as through excitation of acid-sensitive reticulo-ruminal receptors.

Influence of Feeding Level on Digestion and Protein Passage to the Duodenum in Cows Fed High Concentrate Diets

Abstract Dairy cows equipped with rumen and duodenal T-piece cannulae were given 7 diets each fed at two feeding levels, viz. approximately 7 and 14 kg DM per day, equivalent to 1.2 to 1.5 and 2.4 to 3.0 times energy maintenance requirement respectively. The diets consisted of app. 25% barley straw plus concentrates. The concentrates were soybean meal, beet-pulp-molasses, cottonseed cakes, fish meal and grass pellets with 18 or 12% protein. Cromic oxide and polyethylene glycol were given as indigestible markers. Twelve rumen, duodenal and faecal samples were taken to represent a 24-hour period. As a mean for the 7 diets, level of feed intake did not significantly influence neither the passage to the duodenum of non-ammonia-N (NAN) or amino acid-N (AAN) per kg dry matter intake, nor the calculated feed protein degradability in the rumen. Doubling of the feeding level resulted in a significant change in rumen pH from 6.59 to 6.47, in the digestibility of organic matter in the rumen from 37.1% to 39.8% and in the passage of starch + sugar to the duodenum from 11.8 g to 15.4 g per kg dry matter intake. The digestibility of crude fibre in the rumen, and the total digestibility of crude fibre and organic matter was as a mean unaffected by feeding level. Significant interactions between diet and feeding level were found for the passage of NAN and AAN to the duodenum, the calculated degradability of feed protein, the ruminal digestion of organic matter and crude fibre and the total digestion of crude fibre as well as for the passage of starch + sugar to the duodenum per kg dry matter intake.

Influences of dietary sucrose and urea on transfer of endogenous urea to the rumen of sheep and numbers of epithelial bacteria.

1. The rates of transfer of plasma urea to the rumen of six sheep given brome grass (Bromus inermis) pellets alone or with supplements of sucrose or urea were determined using [14C] urea and 14C-labelled sodium bicarbonate infusions during three periods. 2. The sheep were slaughtered after the third period and samples of rumen epithelium were taken for assessment of numbers of adherent bacteria. 3. Maximum transfer (0.31 g nitrogen/h) of urea ot the rumen was observed for sheep given supplements of 150 g sucrose/d plus 20 g urea/d. Maximum clearance of plasma urea to the rumen (rate of urea transfer to the rumen per unit plasma urea concentration, 5.8 1/h) was observed for sheep given 300 g sucrose/d. 4. Urea clearance to the rumen was negatively related to rumen ammonia concentration; the slope of the relationship was increased with each addition of sucrose to the diet. 5. Numbers of facultative bacteria adherent to the rumen epithelium were increased by urea and sucrose supplements. 6. The results are discussed in relation to a hypothesis which relates the ureolytic capability of the bacteria adherent to the rumen epithelium to the control of the rate of transfer of urea into the rumen.

Copper deficiency: a study of prophylaxis and the interaction with cobalt therapy in lambs on improved hill pastures

ABSTRACTAn experiment was conducted with 84 suckling Scottish Blackface twin lambs on an improved hill pasture with a history of cobalt deficiency and molybdenum/sulphur-induced copper deficiency. The dams of 13 pairs of twins were treated with 90 mg copper at parturition (Cue) and one member of each pair was given a cobalt bullet (Co + ). One member of each of a further 29 pairs was treated periodically with 5 to 15mg copper to maintain plasma copper concentrations >0·6mg/l (Cu+) while their siblings received no supplementary copper (Cu). Fourteen of these pairs also received a cobalt bullet (Co + ). Lambs not treated with cobalt are designated Co−.The Cue treatment increased milk copper concentrations, but only for a short time, and resulted in transitory increases in lamb plasma copper concentrations and rate of live-weight gain. At the end of the grazing phase, at approximately 20 weeks of age, Cu+ lambs had gained 0-28 kg more weight than Cue lambs and 158 kg more than Cue lambs, and had higher liver copper concentrations. Cu+ and Cue lambs had heavier and fatter empty bodies and carcasses than Cu− lambs. The cobalt treatment produced no effects at this stage.Fifty-four of the lambs were housed and given dried grass pellets ad libitum. After 83 days liver copper concentrations were higher in Co− than Co+ lambs, and in Cu+ than in Cu− and Cue lambs. The copper treatments had no effect on rate or efficiency of live-weight gain, but Co− lambs gained weight more quickly and more efficiently than Co+ lambs.

Nitrate poisoning in cattle. 3. The relationship between nitrate intake with hay or fresh roughage and the speed of intake on the formation of methemoglobin.

For part 2 see NAR/B 48, 238. 3. In 40 feeding experiments during about 5 years dry or lactating Friesian cows weighing 415 to 670 kg and 3 to 8 years old were given diets of hay, grass pellets, turnips or freshly mown grass in 2 meals daily. During experiments blood from the jugular vein was sampled every 15 min. Cows were induced to increase nitrate intake by being given at least 4 meals of roughage rich in nitrate before blood was sampled. There was a positive relation between nitrate intake and methaemoglobin per cent of total Hb but there were differences within and between different roughages in formation of methaemoglobin. With similar nitrate intake and speed of intake, more Hb was converted into methaemoglobin with hay than with freshly mown grass. That was related to the speed at which the nitrate taken with the roughage was released in the rumen as a substrate for the rumen flora. When hay was soaked in distilled water 80% of the nitrate in the cells diffused into the water within 20 min. With turnip and grass chopped to about 1 cm, 30% of the nitrate diffused into the water within 20 min. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The utilization by lambs of the energy and protein in dried pelleted grass treated with formaldehyde

ABSTRACTA primary growth crop of perennial ryegrass (cv. S24), containing 17% crude protein and 9·9 MJ metabolizable energy/kg dry matter, was artificially dried, ground through a 3·0 mm screen and pelleted either without further treatment (C), or after the application of formaldehyde (T) at a rate of 1 g/100 g crude protein. The C and T diets were each fed to 20 lambs for 77 days. Diets C and T were given ad libitum and at three lower planes of nutrition. Similar amounts of dry matter, nitrogen and digestible energy were consumed at each of the four planes of nutrition by lambs fed diets C and T. Carcass energy, fat and protein retention, and total body energy retention were measured by the comparative slaughter technique and did not differ between the diets (P> 0·05). Metabolizable energy intake was calculated from digestible energy intake using the factor 0·81. The efficiency of utilization of the metabolizable energy for growth and fattening (kf) and the net energy value were calculated by linear regression analysis from the total body energy retention, the calculated metabolizable energy intake and dry-matter intake data scaled to M0·75. They did not differ between the diets (P > 0·05), and were 0·370 (C) and 0·431 (T) for kf, and 2·09 (C) and 1·97 MJ/kg dry matter (T) for net energy.

The influence of pellet size and density on the intake by calves of dried grass pellets given as supplements to hay

ABSTRACTHigh (1·31 kg/1) or medium-density (1·17 kg/1) dried grass pellets of 9, 12 or 18 mm diameter were given to British Friesian male calves of 7 to 14 weeks of age as supplements to chopped hay (Experiment 1). Pellets were given ad libitum but with access limited to two periods of 1½ h per day, and hay was given ad libitum for the remaining 21 h. In Experiment 2, high (1·34 kg/1) or medium-density (1·14 kg/1) dried grass pellets of 18 mm diameter were given to British Friesian male calves of 26 to 30 weeks of age. Pellets were given as supplements to chopped hay as in Experiment 1.There was no effect of pellet size or density on total intake of organic matter or live-weight gain by calves in either experiment. With the exception of animals given pellets of 12 mm diameter in Experiment 1, animals in both experiments consumed less pellets of high density than of medium density, but they were able to compensate for low pellet intake by eating more hay.The coefficients of variation for intake were higher in Experiment 1 than in Experiment 2, and higher for the intake of pellets than for total intake. There was a progressive increase in the intake (g organic matter/kg M0·75 per day) by calves in Experiment 1, whereas in Experiment 2 intake increased for the first 10 days and then remained constant. On average the proportion of pellets and hay consumed did not change in Experiment 1, but in Experiment 2 the proportion of pellets in the feed consumed increased from 53·5 to 60·6%.

Transfer of urea from the blood to the rumen of sheep.

1. The rate of transfer of plasma urea-nitrogen to rumen ammonia was measured by infusion of 15NH4Cl and [15N]urea into sheep given brome grass (Bromus inermis) or lucerne (Medicago sativa) pellets. Urea was infused into the rumen or abomasum of two sheep given brome grass in order to increase the concentration of rumen ammonia. 2. From 6.2 to 9.8 g/d of plasma urea-N were transferred to the rumen of sheep given brome grass pellets and a measurement of 1.3 g nitrogen/d was obtained for a sheep given lucerne pellets. When urea was infused into the rumen of sheep given brome grass pellets the transfer was only 2.8--3.7 g N/d. 3. There was a significant negative correlation between the rate of transfer of plasma urea-N to the rumen and the concentration of rumen ammonia.

Quantitative aspects of the transformations of sulphur in sheep.

1. [35S]sulphate was used to obtain quantitative estimates of the transfer of sulphur between the blood, rumen and postruminal tract of four sheep given brome grass (Bromus inermis) pellets or lucerne (Medicago sativa) pellets at the rate of 33 or 66 g/h. Sodium sulphate (0-4 g S/d) was infused into the rumen or abomasum of sheep given brome grass during four periods of 19 d and was not infused into the sheep during a subsequent period in which lucerne was given. The flow of sulphide, sulphate, microbial S and non-microbial organic S from the abomasum was estimated using 103Ru and 51Cr. 2. The concentration of inorganic sulphate in serum was increased to maximum values of 35-46 mg S/l by infusion of sulphate into the rumen or abomasum. The rate of irreversible loss of serum sulphate and rumen sulphide was positively related to the amount of sulphate infused. 3. Reabsorption of sulphate by the kidney reached a maximum of 0.69-1.1 mmol sulphate/l glomerular filtrate. 4. The transfer of sulphate from blood to the rumen was related to the concentration of inorganic sulphate in serum, attaining maximum values of 133 (+/- 13) mg S/d for sheep given brome grass plus sulphate, and 127-159 mg S/d for sheep given lucerne. 5. Bacteria derived 0.52-0.67 of organic S from rumen sulphide in sheep given brome grass, and approximately 0.45 of bacterial organic S was derived from sulphide for sheep given lucerne. Protozoa derived approximately 0.90 of organic S from bacteria. 6. It was estimated that endogenous organic S contributed 300-340 mg S/d to the rumen, and that 0.24-0.45 of S digested in the rumen was derived from endogenous sources.