P. E. V. Williams

Ammonia treatment of straw via the hydrolysis of urea. II. Additions of soya bean (urease), sodium hydroxide and molasses; effects on the digestibility of urea-treated straw

Samples of barley straw were sprayed with solutions of urea (U), urea plus a dry addition of soya bean meal (50 g/kg straw dry matter (DM)) (UB) alone or with sodium hydroxide (15 g/kg straw DM) (UBS), or urea plus molasses (50 g/kg straw DM) (UM). Water was added to lower the DM content of the straw to 700 g kg−1, and the level of urea applied was 70 g/kg straw DM. A further quantity of straw was treated with aqueous ammonia (40 g/kg straw DM). Two-kilogramme lots of each treated straw were sealed in polythene bags and stored for 40 days at 18°C. From the levels of gaseous ammonia in the bags on Day 40, there were indications that the rate of hydrolysis of urea was decreased by treatment UBS, but was increased by molasses addition (UM) compared with straw treated with urea alone (U). The addition of soya bean meal (UB) as a source of urease had no effect. After 48 h incubation in the rumen of steers, samples from Treatments UBS, UB and UM were not significantly different to samples from Treatment U in DM degradability. The DM degradability (%) of a control, untreated straw or samples of straw treated with urea (U) or ammonia (A) was 41.4 < 47.1 < 59.1, respectively (P < 0.001). Large quantities of straw (200 kg) were treated as for U, UBS, UM and A. The straw was stored in polythene bags for 40 days when the mean ambient temperature was 5.5°C. Diets of treated straw and dried grass (1:1 on a DM basis) were offered to sheep and digestibility was determined. There were no differences in DM digestibility between diets made up with dried grass and straw (U, 0.64; UBS, 0.65; UM, 0.65; A, 0.65). The DM digestibility of dried grass plus untreated straw was 0.56. Apparent DM digestibility of the straw alone in the above diets was 0.49, 0.51, 0.52, 0.51 and 0.34, respectively. Both ammonia and urea treatment significantly (P < 0.001) increased the digestibility of straw.

Ammonia treatment of straw via the hydrolysis of urea. I. Effects of dry matter and urea concentrations on the rate of hydrolysis of urea

Abstract Samples of barley straw were sprayed with solutions of urea to yield treated straws containing 450–750 g dry matter (DM) per kg straw and 35.3–105.9 g urea/kg straw DM. Two kg of each treated straw was sealed in a polythene bag and stored for 6 weeks at 18°C. After storage, samples were analysed for urea nitrogen, water-soluble and insoluble nitrogen, and their DM degradability was determined by the nylon bag technique. Ammonia was released from the hydrolysis of urea. Degree of hydrolysis was significantly affected by the concentration of DM in the straw; when urea was applied at 70.5 g/kg DM the degree of hydrolysis was 100 and 36.5% when the straw DM was 450 and 750 g kg −1 , respectively. Raising the level of urea applied from 35.3 to 105.9 g kg −1 straw DM when the concentration of DM was 600 g kg −1 straw significantly increased the weight of urea hydrolysed. Urea treatment significantly increased the degradability of the straw after 48 h incubation in the rumen of steers. The degree of improvement in degradability was significantly affected by the DM content of the straw, but not by the amount of urea applied. Heat or antibiotic treatment of the straw showed that some hydrolysis occurred as a result of bacterial activity, but suggested that the contribution to hydrolytic activity from plant enzymes was minimal.

The effect of frequency of feeding milk replacer to pre-ruminant calves on respiratory quotient and the efficiency of food utilization

Thirty-four British Friesian bull calves were used in experiments to identify diurnal patterns of respiratory quotient (RQ), as an indicator of substrate utilization and to measure energy balance when the same daily amount of milk replacer was given on either 1, 2, 4 or 6 occasions. Each calf spent two 4-day periods in an open-circuit respiration chamber followed immediately, in selected calves, by an 8-day period in a metabolism crate, period 1 starting when calves were 12 days of age and period 2 at 28 days of age. The amount of milk replacer given daily was 32 and 48 g/kg M 0·75 during periods 1 and 2 respectively. Neither rate of live-weight gain nor the energy balance of the calves was affected by frequency of feeding. However, raising the frequency of feeding from one to four times daily significantly affected the pattern of RQ. Reduced feeding frequency tended to raise the mean maximum and lower the mean minimum values of RQ; reducing the frequency of feeding significantly increased the range in RQ (F The apparent dry-matter digestibility of the milk replacer was higher in 36-day-old than in 20-day-old calves (0·93 v. 0·88; s.e.d. 0·011, P v. 0·73; s.e.d. 0·019). In 20-day-old calves, there was a linear increase in fat digestibility with increased frequency of feeding ( P The results suggest that calves given milk replacer once daily (at a level of intake of 32 rising to 48 g milk powder per kg M 0·75 ) do not pass through a diurnal period of severe nutrient deprivation and that raising frequency of feeding would do little to improve efficiency of energy utilization.

The use of kidney beans (Phaseolus vulgaris) as protein supplements in diets for young rapidly growing beef steers

Abstract Rolled barley was pelleted with supplementary minerals and vitamins (Diet 1), or with supplements of either soya bean meal (Diet 2) or with 50 or 75% of the supplementary protein supplied by the soya being replaced by protein from kidney beans ( Phaseolus vulgaris L. cv. Processor) (Diets 3 and 4, respectively). The crude protein content of Diet 1 was 11.5% of the dry matter, and in Diets 2, 3 and 4, it was approximately 15%. In Trial 1, groups of four steers with mean live weight 203 ± 4.8 kg were allocated to each of the dietary treatments. Blood samples were obtained from these steers before they received the experimental diets, and 10 and 13 days after they were introduced to the diets. Four days after the steers were offered the diets, six out of the eight steers given diets containing kidney beans were excreting loose watery faeces. All steers given diets containing kidney beans developed anti-lectin antibodies to a varying extent by Day 13 of the trial. In Trial 2, the pelleted diets used in Trial 1 were offered with 2 kg of hay per day to groups of eight steers of similar type and weight. Over a 66-day period, the live-weight gains of steers offered Diets 1–4 were 1.06, 1.28, 1.05 and 0.86 ± 0.11 kg/day, respectively. Steers consumed significantly less of the pellets which contained kidney beans, Treatments 3 and 4 giving intakes of 6.5 and 6.2 kg/day, respectively, compared with 6.8 and 7.1 kg/day for Treatments 1 and 2, respectively. The efficiency of food conversion of steers on Treatments 1–4 was 6.5, 5.6, 6.3 and 8.5, respectively. Incorporating kidney beans in the diets of yearling cattle was detrimental to the health of the cattle and depressed daily live-weight gains.

Digestibility studies on ammonia-treated straw

Abstract Barley straw (cultiva Sonja, a winter variety), either treated with anhydrous ammonia (30 g NH 3 /kg straw dry matter) in an oven at 90°C for 16 h or left untreated, was offered to eight sheep in digestibility trials. The digestibility of the dry matter of ammoniatreated and untreated straw was 0.50 and 0.42, of organic matter 0.52 and 0.45, and of acid detergent fibre 0.59 and 0.47, respectively. A series of digestibility trials is summarised in which ammonia-treated straw was offered with supplements of either rolled barley, turnips, fishmeal, cassava or molasses to either sheep or cattle. When the straw constituted less than 50% of a diet which included either rolled barley or turnips, the digestibility of acid detergent fibre in the diet was lower than recorded when straw was offered alone. The apparent digestibility of the straw DM, in the diets with rolled barley or turnips, was also lower than when the straw was offered alone. However, when the supplement constituted approximately 5% of the DM of the diet, supplementation of ammoniatreated straw with either fishmeal, cassava or molasses tended to increase the digestibility of ADF and the apparent DM digestibility of the straw. The results were interpreted as showing that changes in bacterial cellulolysis were occurring according to the levels of supplementation used, high levels of rapidly fermentable carbohydrate in diets with straw tending to depress digestion of cellulose by bacteria, but small additions of either protein or rapidly fermentable carbohydrates stimulating it.

Effects on food intake, rumen development and live weight of calves of replacing barley with sugar beet-citrus pulp in a starter diet

In three experiments the effects of replacing barley with citrus or unmolassed beet pulp in starter diets for calves was examined. In experiment 1, 40 Friesian bull calves were offered to appetite from 14 to 91 days of age one of four complete pelleted diets, each of which contained 200 g ground straw per kg and n i which the ratio of barley to pulp (citrus and beet pulp in the ratio 1:1) was 100:0 (A); 67:33 (B); 33:67 (C) and 0:100 (D). All diets contained 12·1 MJ metabolizable energy and 187 g crude protein per kg dry matter (DM). Milk replacer containing 200 g fat per kg was offered once daily (0·44 kg/day) until day 49 when the calves were abruptly weaned. Up to weaning (days 14 to 49) and after weaning (days 50 to 91) intake of DM was significantly increased by replacing barley with pulp ( P v. 0·58 for A v. mean of B, C and D) but lower after weaning (0·73 v. 0·68) than of calves given the cereal-based diet. In experiment 2, 65 calves were given diets similar to A and C except that the pulp was supplied totally by unmolassed beet pulp, they were given only 0·35 kg milk replacer per day and weaned on day 35. The results were similar to those obtained in experiment 1; between days 14 to 84 intake was higher ( P P

The effects on feed intake, growth and digestibility of nutrients of including calcium soaps of fat in diets for young calves

Abstract Twenty four male Friesian calves were given, once daily from day 14 to weaning on day 56, 440 g milk replacer dissolved in 3 litre of warm water. From 14 days of age the calves were offered, ad libitum, either a complete diet based on rolled barley, sugar beet pulp, barley straw and a protein supplement or one of three diets in which the rolled barley and sugar beet pulp of the basal diet were partly replaced by “protected fat”, i.e., calcium soaps of fat. This additional fat was included in the proportions 0, 0.05, 0.10 and 0.20 of the diet such that the content of total lipid in the diets was either 25.0, 62.5, 105.9 or 180.8 g/kg dry matter (DM) and the metabolizable energy (ME) content 11.5, 12.3, 13.2 and 14.8 MJ ME/kg DM, respectively. All diets contained approximately 16.6 g rumen degradable nitrogen and 13.1 g undegradable nitrogen per kg of diet. The addition of fat led to a depression in DM intake and live-weight gain ( P

The effects on growth, food intake and rumen volume of including untreated or ammonia-treated barley straw in a complete diet for weaning calves

Two experiments were conducted using British Friesian bull calves to determine the effects on growth, food intake and rumen volume of including 0, 150, 200 or 250 g ammonia-treated (35 g/kg dry matter (DM)) or untreated barley straw per kg pelleted concentrate based on cereal. All calves received once daily 440 g milk replacer powder reconstituted in 3 1 warm water, were weaned at 56 days of age and given one of the seven pelleted diets to appetite from 14 days of age. In experiment 1, the seven diets were allocated at random to 70 calves. Food intake was increased by the inclusion of straw but there was no effect on intake of the increased concentration of straw; daily DM intake from 14 to 77 days of age was 1·36 and 1·77 kg/day respectively for diets with or without straw. From 14 to 56 days of age intake of concentrate was increased by the addition of straw but was negatively correlated with the concentration of straw in the diet. After weaning inclusion of straw, whilst increasing total intake, tended to depress intake of cereal. Treatment with ammonia increased the nitrogen concentration in the straw but had no effect on the digestibility or amount of diet consumed. After adjustment was made for gut fill, the increases in weight between 4 and 84 days of age of calves given 150, 200 or 250 g straw per kg food were 6·6, 1·2 and 1·0 kg respectively greater than those that occurred when there was no straw in the diet. DM digestibility of all diets was above 0·67 but the mean digestibility of acid detergent fibre was low (0·19). The pH and ammonia concentration of rumen liquor were low and below the optimum for cellulose digestion. In experiment 2, rumen volume was measured in vivo in a group of 24 calves given the same diets as in experiment 1. Rumen volume was increased two fold at 42 days of age by the addition of straw to the diet (5·6 v. 2·6 1, P v. 11·9 1, P

Turnips with chemically-treated straw for beef production 2. Effect of turnips on the degradability of straw in the rumen

The nylon bag technique was used to determine the effects of offering to steers an allowance of turnips in a diet based on straw on the degradation of dry matter and acid-detergent fibre of the straw. Rumen-cannulated steers were offered basal diets of (a) sodium hydroxide (NaOH)-treated straw ad libitum , (b) NaOH-treated straw plus turnips (50 g dry matter per kg W 0·73 ) offered once daily or (c) turnips ad libitum . Samples of straw, treated with NaOH, anhydrous ammonia (NH 3 ,) or untreated straw were incubated in nylon bags in the rumen along with each of the basal diets. Additionally molasses (66 g dry matter per kg W 0·75 ) was infused into the rumen of the steers offered the NaOH-treated straw. Dry matter and fibre losses of straw from nylon bags were in the order NaOH-treated > NH 3 ,-treated > untreated; there was no interaction ( P > 0·05) between method of straw treatment and effect of basal diet on 40-h or 72-h dry matter or fibre degradability. Supplementation of the basal straw diet with either turnips or molasses depressed ( P P

Ammonia-treated barley straw and rolled barley offered either together, in a mixed ration, or successively to beef steers

Abstract Barley straw treated with anhydrous ammonia at a rate of 40 g per kg of straw dry matter (DM) and rolled barley were offered to 20 steers weighing initially 350 kg. Each steer was offered in total approximately 600 kg of straw DM and approximately 525 kg of barley DM. Ten steers were offered the straw alone in the long form at the beginning of the trial followed by the rolled barley alone. The remaining 10 steers were offered straw which had been ground through a 40-mm screen and mixed with the rolled barley in a complete diet. Dry matter digestibility coefficients of the ammonia-treated straw and the mixed straw plus barley diet were 0.52 and 0.57 ± 0.026, respectively. The DM digestibility coefficient of rolled grain in the mixed diet was predicted from the digestibility of starch to be 0.78 and the DM digestibility of straw in the mixed diet, determined by difference, was 0.39. Although steers offered the straw followed by rolled barley took on average 39 days longer to consume their total food allowance, cold dressed carcass weights of the two groups were not significantly different nor was there any difference in the carcass composition of the two groups of steers as determined by specific gravity measurements. Maintenance energy requirements were calculated for the two groups of steers and although the same amount of food was consumed by both groups and the energy required for maintenance was higher in the group offered straw followed by barley, the depression in the energy available from straw offered in a mixed diet caused the same total amount of metabolizable energy to be available for carcass gain to both groups.