Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs

Two feeding experiments were conducted in which lambs were given a basal diet of barley straw, supplemented with urea and minerals. The aim of the experiments was to increase lamb performance by (i) supplementation of the diet with protein meals that were largely undegraded in the rumen, (ii) treating the barley straw with anhydrous ammonia to increase its digestibility, or (iii) a combination of both.In Experiment 1, lambs were given the basal diet supplemented with 0, 60, 120, 180, 240, 300 or 360 g heat-treated protein-meal/kg straw. At the 300 g/kg level of supplementation, the protein pellet increased liveweight gain by 82 g/day, intake of barley straw by 110 g/day, and wool growth by 3.3 g/day, in comparison with unsupplemented lambs.In Experiment 2, untreated barley-straw or barley straw treated with anhydrous ammonia (4% w/w) was given to growing lambs. Each diet was supplemented (g/kg straw diet) with 100, 200 or 300 of two heat-treated protein-meals. Ammoniation of the barley straw increased dry matter (DM) digestibility in vitro from 49 to 57%, and hemicellulose content was reduced by 20%. Total N content of the straw was increased from 4.6 to 9.8 gN/kg DM by ammoniation, 65% of the increased N being potentially degradable in the rumen. As a result of ammoniation, digestible dry-matter intake of lambs was increased by 60 g DM/day and liveweight gain increased by 15 g/day.There was no significant difference between the two protein supplements with respect to either total feed intake or liveweight gain. Liveweight gain was significantly increased by both supplements (71, 106 and 125 g/day for each level of supplementation, respectively), but neither supplement had a significant effect on the intake of barley straw.Supplementation of a low-protein, low digestible diet of barley straw with a pelleted protein-meal considerably increased liveweight gain of growing lambs and maintained straw intake. By comparison, treatment of barley straw with anhydrous ammonia increased its digestibility, but had only a minor effect on lamb performance.     

Methods of improving the utilization of cereal straw by ruminants. II. Further studies on dried grass as a supplement for lambs

Sixteen growing castrated lambs (37.0 ± 3.31 kg) were used in two 5 × 5 and one 6 × 6 Latin squares to measure the intake and digestibility of: (1) urea—molasses-treated straw, or mixtures containing (2) 25; (3) 50; or (4) 75% dried grass; and (5) grass alone. The dry matter intake was 40, 50, 69, 84 and 90 g day^?1 per kg of metabolic live weight (P<0.001), and digestibility was 470, 489, 591, 671 and 735 g kg^?1, respectively, for the above treatments. The dry matter intake of lambs offered diets 2, 3 and 4 as complete diets was 47, 56 and 66 g day^?1 kg of metabolic live weight, and digestibility was 513, 621 and 673 g kg^?1, respectively. When the feeds were offered separately, dry matter intake was 54, 63 and 78 g day^?1 per kg of metabolic live weight and digestibility was 541, 582 and 662 g kg^?1, respectively. Dry matter intake for mixed diets was higher (P<0.01) than for feeds given separately.     

Alkali treatment of straw for ruminants. I. Utilization of complete diets containing straw by beef cattle

In the first of two experiments, 40 Friesian steers weighing initially 300 kg were fattened on diets containing barley and soya bean meal alone (C) or with inclusions of 40% untreated straw (WS₄₀) or 40 or 60% alkali-treated straw (AS₄₀ and AS₆₀). The straw was coarsely milled into a horizontal mixer, where sodium hydroxide was applied as a 16% solution providing $\text{80}\text{kg NaOH}\text{t straw dry matter (DM)}$. Intakes of DM (kg/d) were: C, 7.88; AS₄₀, 9.67; AS₆₀, 9.23; WS₄₀, 8.60, and empty body weight gains (kg/d, in the same order) were 1.16, 1.03, 0.82 and 0.78.In the second experiment there were four diets, all containing 60% straw and 40% concentrates. The straw was coarsely milled (M) or chopped by forage harvester (C), and treated with alkali (A) or untreated (U). In a trial of latin square design, intake (kg DM/d) was; MU, 7.77; MA, 10.37; CU, 7.44; CA, 10.12. In a longer trial with five steers per diet, liveweight gains (kg/d, in the same order) were 0.70, 1.09, 0.71 and 1.18. The digestibility of DM for the four diets was 60.0, 72.7, 60.3 and 72.0%.The utilization of the energy of the diets, and the economic value of alkali treatment, are discussed.     

Selenium persistency and speciation in the tissues of lambs following the withdrawal of dietary high-dose selenium-enriched yeast

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in post mortem tissues of lambs in the 6 weeks period following the withdrawal of a diet containing high-dose selenised yeast (HSY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty Texel × Suffolk lambs used in this study had previously received diets (91 days) containing either HSY (6.30 mg Se per kg dry matter (DM)) or an unsupplemented control (C; 0.13 mg Se per kg DM). Following the period of supplementation, all lambs were then offered a complete pelleted diet, without additional Se (0.15 mg Se per kg DM), for 42 days. At enrolment and 21 and 42 days later, five lambs from each treatment were blood sampled, euthanased and samples of heart, liver, kidney and skeletal muscle (longissimus dorsi and psoas major) tissue were retained. Total Se concentration in whole blood and tissues was significantly (P < 0.001) higher in HSY lambs at all time points that had previously received long-term exposure to high dietary concentrations of SY. The distribution of total Se and the proportions of total Se comprised as SeMet and SeCys differed between tissues, treatment and time points. Total Se was greatest in HSY liver and kidney (22.64 and 18.96 mg Se per kg DM, respectively) and SeCys comprised the greatest proportion of total Se. Conversely, cardiac and skeletal muscle (longissimus dorsi and psoas major) tissues had lower total Se concentration (10.80, 7.02 and 7.82 mg Se per kg DM, respectively) and SeMet was the predominant selenised amino acid. Rates of Se clearance in HSY liver (307 μg Se per day) and kidney (238 μg Se per day) were higher compared with HSY cardiac tissue (120 μg Se per day) and skeletal muscle (20 μg Se per day). In conclusion, differences in Se clearance rates were different between tissue types, reflecting the relative metabolic activity of each tissue, and appear to be dependent on the proportions of total Se comprised as either SeMet or SeCys.     

Lysine requirements of imported European pigs in the humid lowland tropics from 23 to 62 kg liveweight

The responses of 144 Large White × Landrace pigs (72 castrated males and 72 females; mean initial liveweight approximately 23 kg) to graded additions of L-lysine monohydrochloride to a basal diet containing yellow maize and groundnut meal and 180 g crude protein per kg were studied. Total dietary lysine levels ranged from 5–12 g kg^?1. All diets contained digestible energy of 15.44–16.02 MJ kg^?1 DM. The pigs were individually fed from 23 to 33, 47 or 62 kg liveweight. Growth performance, carcass characteristics, nitrogen retention and plasma urea concentration were employed as response criteria. Influence of sex on lysine requirements for optimum growth, nitrogen retention and efficiency of essential amino acids utilization measured by minimum plasma urea concentration was also investigated.Supplementing the basal diet with L-lysine monohydrochloride significantly (P < 0.001) improved growth performance. Castrated male pigs grew faster and responded better to dietary lysine supplementation than gilts. No apparent decline in lysine requirements for optimum growth performance was observed for the two sexes of pigs as they got older. Optimum growth performance in castrated males was obtained with 9, 8 and 8 g lysine kg^?1 diets for the liveweight ranges 23–33, 23–47 and 23–62 kg, respectively. Optimum growth performance of the gilts for all three liveweight ranges was obtained at an estimated dietary lysine concentration of 11 g kg^?1.Optimum lean deposition, carcass leanness and other carcass measurements were obtained at 8 g lysine kg^?1 diet. Carcass data were not analysed for influence of sex.Plasma urea concentration showed further evidence of a quicker and cheaper indirect index of dietary amino acid adequacy in pigs. Minimal plasma urea concentration was obtained at 7–8 g lysine kg^?1 diet for the three liveweight ranges investigated.In a humid tropical environment, such as Ibadan, the dietary lysine requirement of Large White × Landrace pigs of 23–62 kg is about 9 g lysine kg^?1 diet for optimum growth performance and carcass quality, but nitrogen metabolism and plasma urea data suggest a lower level of to 7–9 g lysine kg^?1 diet.     

Energy and protein requirements of Santa Ines lambs,a breed of hair sheep

An experiment was carried to evaluate the energy and protein requirements for the growth and maintenance of lambs of different sex classes. In all, 38 hair lambs (13.0±1.49 kg initial BW and 2 months old) were allocated in a factorial design with diet restriction levels (ad libitum, 30% and 60% feed restriction) and sex classes (castrated and non-castrated males). Four animals from each sex class were slaughtered at the beginning of the trial as a reference group to estimate the initial empty BW and body composition. The remaining lambs were weighed weekly to calculate BW gain (BWG), and when the animals fed ad libitum reached an average BW of 30 kg, all of the experimental animals were slaughtered. Before slaughter, fasted BW (FBW) was determined after 18 h without feed and water. Feed restriction induced reductions in body fat and energy concentration, whereas water restriction showed the opposite effect, and the protein concentration was not affected. The increase in BW promoted increases in body fat and energy content, and these increases were greater in castrated lambs, whereas the protein content was similar between classes tending to stabilize. The net energy required for gain (NE_g) and the net protein required for gain (NP_g) were not affected by sex class; therefore, an equation was generated for the combined results of both castrated and non-castrated lambs. The NE_g varied from 1.13 to 2.01 MJ/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The NP_g varied from 24.57 to 16.33 g/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The metabolizable energy efficiency for gain (k_g) was 0.37, and the metabolizable protein efficiency for gain (k_pg) was 0.28. The net energy required for maintenance (NE_m) and the net requirement of protein for maintenance (NP_m) did not differ between castrated and non-castrated lambs, with values of 0.241 MJ/kg FBW^0.75 per day and 1.30 g/kg FBW^0.75 per day, respectively. The metabolizable energy efficiency for maintenance (k_m) was 0.60, and the efficiency of metabolizable protein use for maintenance (k_pm) was 0.57. Nutritional requirements for growth and maintenance did not differ between castrated and non-castrated lambs. This study emphasizes the importance of updating the tables of international committees and of including data obtained from studies with sheep breeds raised in tropical conditions, with the purpose of improving the productive efficiency of the animals     

Alkali treatment of straw for ruminants. II. Nutritive value of straw ensiled after alkali treatment

In the first of two experiments barley straw was treated with a 16% solution of $\text{NaOH}\text{t}$ dry matter (DM) and ensiled for one year. It was satisfactorily preserved, having a pH of 10 and counts of 10⁴ mesophilic bacteria and 10³ fungal propagules per g. When this straw was mixed with concentrates (50:50, DM basis) and given to sheep, DM intake and digestibility were 102 g/kg W^0.75 per day and 67.3%. Comparable values for a diet based on freshly-treated straw were 88 g and 66.5%.In the second experiment, a 6-tonne batch of alkali-treated barley straw was ensiled for 2–4 months, then mixed with 40% concentrates and given to 370-kg steers for 66 days. Intake and growth rate were 10.23 and 1.08 kg/d, compared with 9.06 and 1.00 kg/d for steers given a diet based on freshly-treated straw. The latter diet was less digestible (for sheep) than the former.It is concluded that the feeding value of stored straw is as high as that of freshly-treated material.     

Effects of oilseed meals and grain–urea supplements fed infrequently on digestion in sheep: 2. Cereal straw diets

An experiment examined the intake, growth responses and rumen digestion of young sheep fed ad libitum oat or barley straws alone or supplemented with approximately isonitrogenous amounts of barley grain and urea (Bar/N), safflower seed meal (SAF) or linseed meal (LIN) supplements provided at 3 day intervals. The supplements comprised 15–22% of total dry matter (DM) intake. Sheep offered either of the straws alone consumed 35.0–37.2 g DM/kg liveweight (LW^0.75) per day of straw and an estimated 2.03–2.07 MJ metabolizable energy (ME) per day, and lost 85–97 g LW per day. Supplements increased (P<0.05 or <0.001) voluntary intake of straw and of total DM, and the organic matter (OM) digestibility of the entire diet. Each of the supplements increased (P<0.001) the estimated ME intake to a similar extent and changed the rapid LW loss of sheep fed straw alone to approximate LW maintenance. Rumen ammonia concentrations in sheep fed barley and oat straws alone (12 and 24 mg NH₃/l, respectively) were expected to be deficient for microbial activity, but were increased (P<0.001) by provision of the supplements. Digestion of straw in synthetic fibre bags incubated in the rumen was markedly increased (P<0.01 or <0.001) when supplements were provided. Rumen pH was depressed briefly to pH <6.0 by the Bar/N, but not by the LIN or SAF, supplements. In young sheep fed cereal straws and losing LW rapidly the oilseed meal supplements increased wool growth more than the barley grain–urea supplements, but both types of supplement increased ME intake similarly and were equally effective to reduce the extent of LW loss.     

Ensiled alkali-treated straw. I. Effect of level and type of alkali on the composition and digestibility in vitro of ensiled barley straw

In three experiments barley straw chopped to 5 cm nominal particle length was ensiled in laboratory silos for 90 days after treatment with alkali. In the first two experiments, NaOH was added at 0, 1.05, 2.10, 3.15 or 4.20 g per 100 g straw dry matter (DM) (Experiment 1) or at 0, 2.5, 5.0, 7.5 and 10.0 g per 100 g straw DM (Experiment 2) in solutions at either 60 ml or 120 ml solution per 100 g straw DM. Digestibility in vitro of organic matter (OM) and digestible OM in DM (DOMD) increased with increasing level of NaOH. The effect of volume of solution on digestibility was small. The pH of the straws decreased during storage. The content of neutral detergent fibre decreased as the level of NaOH increased, but there was relatively little change in the contents of acid detergent fibre or acid detergent lignin. Lactate and acetate were detected in all silages, and butyrate was present in silages made from straws treated with less than 5 g NaOH per 100 g straw DM. On opening the silos little moulding was seen and the temperature of the straws remained close to ambient in both experiments throughout 16 days of subsequent exposure to air.In the third experiment, the comparative effects of Ca(OH)₂ and KOH were studied alone and in combination ($\text{50}\text{50}$ by weight) with NaOH. KOH mixed with NaOH gave levels of DOMD in vitro similar to those obtained with NaOH alone. Ca(OH)₂, whilst improving DOMD, was slightly less effective than the other alkalis.The optimum level of alkali for the treatment of barley straw prior to ensiling appeared to be 7.5 g/100 g straw DM. At this level of addition, DOMD in vitro would be expected to be about 65%. Ca(OH)₂ is worth further attention as an alternative to NaOH.     

The feeding value for ruminants of straw and wholecrop barley and oats treated with anhydrous or aqueous ammonia or urea

Ammonia-treated or untreated barley straw supplemented with urea was given as the only feed to two groups of Friesian heifers weighing approximately 550 kg. The digestibility of dry matter (DM) was 58.8 and 49.9%, daily feed intake was 5.88 and 3.87 kg and daily liveweight change was +324 and -447 g for the ammonia-treated and control barley straw diets, respectively.Anhydrous or aqueous ammonia (NH₃) was injected into large round straw bales covered with plastic. The rates of degradation of barley straw in nylon bags and digestibility in vivo were the same for both ammonia treatments. The distribution of N in the bales was also similar and uniform with both treatments. No differences were recorded in the rate of degradation in nylon bags if the plastic was removed 2 or 8 weeks after treatment.Anhydrous or aqueous ammonia or isonitrogenous amounts of urea were injected into large round bags containing whole-crop barley or oats collected with a forage harvester. The digestibility of starch by steers was about 92% for ammonia-treated samples and 78% for the urea-treated samples. Urea and ammonia efficiently preserved the whole-crop materials but untreated control samples and samples treated with NaOH deteriorated during storage.     

The partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows

The objectives of the study were to determine the effect of the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea on the performance, metabolism and whole-tract digestibility in mid-lactation dairy cows. Forty-two Holstein–Friesian dairy cows were allocated to one of three dietary treatments in each of three periods of 5 weeks duration in a Latin square design. Control (C) cows were offered a total mixed ration based on grass and maize silages and straight feeds that included 93 g/kg dry matter (DM) soyabean meal and 61 g/kg DM rapeseed meal. Cows that received either of the other two treatments were offered the same basal ration with the replacement of 28 g/kg DM soyabean and 19 g/kg DM rapeseed meal with either 5 g/kg DM feed grade urea (U) or 5.5 g/kg DM of the slow-release urea (S; Optigen^R; Alltech Inc., Kentucky, USA), with the content of maize silage increasing. There was no effect (P > 0.05) of dietary treatment on DM intake, which averaged 22.5 kg/day. Similarly, there was no effect (P > 0.05) of treatment on daily milk or milk fat yield but there was a trend (P = 0.09) for cows offered either of the diets containing urea to have a higher milk fat content (average of 40.1 g/kg for U and S v. 38.9 g/kg for C). Milk true protein concentration and yield were not affected by treatment (P > 0.05). Milk yield from forage and N efficiency (g milk N output/g N intake) were highest (P < 0.01) in cows when offered S and lowest in C, with cows receiving U having intermediate values. Cows offered S also tended to have the highest live weight gain (0.38 kg/day) followed by U (0.23 kg/day) and C (0.01 kg/day; P = 0.07). Plasma urea concentrations were higher (P < 0.05) at 2 and 4 h post feeding in cows when offered U and lowest in C, with animals receiving S having intermediate values. There was no effect (P > 0.05) of treatment on whole-tract digestibility. In conclusion, the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea can be achieved without affecting milk performance or diet digestibility, with the efficiency of conversion of dietary N into milk being improved when the slow-release urea was fed.     

Ensiled alkali-treated straw. II. The nutritive value for young beef cattle of mixtures of ensiled or frozen alkali-treated straw and ryegrass silage

Ensiled or frozen barley straw, treated with 7.5 g NaOH and 120 ml solution per 100 g DM prior to storage, was given in mixtures with ryegrass silage to young calves, initially 100 kg live weight. Urea was added to the straw at feeding at 2.5% of the dry matter (DM) and soya bean meal was given at 0.3% live weight per day in all treatments. Voluntary intake, digestibility and live-weight gain were similar for the two types of treated straw. Intake of metabolisable energy and weight gain decreased with increasing level of straw in the diet, averaging 889 g per head per day for a control diet of grass silage (91.7% of total diet DM), and 749, 550 and 150 g per head per day when the proportion of straw DM to grass silage DM was 33: 66, 66 : 33 and 100 : 0, respectively. Whilst alkali-treated straw cannot replace high quality grass silage with the same nutritional efficiency, weight gains in excess of 500 g/day can be reached if the proportion of straw is less than half the total DM.     

Reducing the potential copper toxicity of concentrates to sheep by the use of molybdenum and sulphur supplements

A high copper (Cu) diet (45.3 μg Cu/g DM) was given to three groups of animals, ♂ or ♀ Scottish Blackface and ♂ Finnish Landrace lambs, without added molybdenum (Mo), or with 2, 4, 8 or 16 mg Mo/kg DM added in a 3 × 5 factorial experiment lasting 18–27 weeks. Sodium sulphate, providing 2 g S/kg, was added with each Mo supplement.Six of the nine lambs not given supplementary Mo + S died of Cu poisoning but those given Mo + S survived. Histological evidence of subclinical hepato-toxicity was found in Mo + S supplemented lambs but it decreased in severity as the level of added Mo increased. Plasma aspartate amino-transferase (PAAT) concentrations were elevated in unsupplemented lambs from week 9 and in lambs given 2 mg Mo/kg from week 12 but they remained normal in lambs given 4–16 mg Mo/kg DM. Successive increments in dietary Mo reduced the increase in liver Cu after 18–20 weeks from 1450 to 735, 483, 445 and 131 μg/g DM. The proportion of ingested Cu (y%) retained in the liver was related to dietary Mo (x, mg/kg DM) by the equation y = 2.6 ? 1.66 log x ± 0.21 (r = 0.98; 2 d.f.).Finnish Landrace lambs retained 50% less Cu in their livers, had lower PAAT levels and showed less histological evidence of liver damage than ♂ Scottish Blackface lambs. The latter had higher PAAT levels and a higher mortality from Cu poisoning than ♀ Scottish Blackface lambs although the two sexes retained similar proportions of ingested Cu in their livers.The results are discussed in relation to the practical use of Mo + S to prevent Cu poisoning in sheep.     

The effects of grain treatment, grain feed level and grass silage feed value on the performance of and meat quality from, finishing beef cattle

A completely randomised design study involving 132 continental crossbred beef steers was undertaken to evaluate the effects of method of grain treatment and feed level, and grass silage feed value on animal performance, carcass characteristics and meat quality of beef cattle. Winter wheat was harvested and the grain was stored either ensiled crimped and treated with 4.5 l/t of a proprietary acid-based additive (crimped), ensiled whole and treated with 20 kg feed-grade urea per t (urea) or stored conventionally in an open bin treated with 3 l propionic acid per t. Two grass silages, of contrasting feed value (L and H) were ensiled. For the conventional, crimped and urea treatments, grain dry matter (DM) concentrations were 802, 658 and 640 g/kg, respectively. For the L- and H-feed value silages, DM concentrations were 192 and 240 g/kg and D values were 671 and 730 g/kg DM, respectively. The silages were offered as the sole forage supplemented with either conventional, crimped or urea-treated grain-based concentrate at either 3.5 or 6.0 kg DM per steer per day. The grain supplement consisted of 850 and 150 g/kg DM of grain and citrus pulp, respectively. For the conventional, urea and crimped treatments, DM intakes were 8.85, 9.43 and 9.04 kg/day (standard error (s.e.) = 0.129); estimated carcass gains were 0.60, 0.55 and 0.61 kg/day (s.e. = 0.020), respectively. For the low- and high- feed value grass silages, estimated carcass gains were 0.56 and 0.61 kg/day (s.e. = 0.014), respectively. For the low and high grain feed levels, estimated carcass gains were 0.56 and 0.61 kg/day, respectively. Grain treatment, grain feed level or silage feed value did not alter (P > 0.05) meat quality, lean colour or fat colour. There were significant silage feed value × grain feed level interactions (P < 0.05) for final live weight (LW) and daily live-weight gain (DLWG). Increasing grain feed level increased final LW and DLWG when offered with the low-feed value silage, however, grain feed level had no effect on final LW or DLWG when offered with the high-feed value silage. It is concluded that urea treatment of grain increased silage intake and feed conversion ratio (kg DM intake per kg carcass) and tended to decrease carcass gain. Crimping provides a biologically equally effective method to store grain as conventional methods. Improving grass silage feed value had a greater impact on animal performance than increasing grain feed level by 2.4 kg DM per day.     

Intestinal amino acid absorption in lambs fed fresh Lucerne ( Medicago sativa) during an established Trichostrongylus colubriformis infection

The effects of an established Trichostrongylus colubriformis infection on amino acid (AA) absorption from the small intestine and their availability to other tissues were determined in lambs 48 days post infection. The lambs were fed fresh Lucerne (Medicago sativa; 800 g dry matter (DM)/day) and dosed with 6000 L3 T. colubriformis larvae for 6 days (n = 5) or kept as parasite free controls (n = 6). Faecal egg production was monitored every second day from day 22 to day 48. A nitrogen (N) balance was conducted on days 35 to 43 after infection, and digesta flow and AA concentration measurements were made on day 44. On day 48 after infection, blood was continuously collected from the mesenteric artery and vein, plasma harvested and AA concentrations measured. Faecal egg production peaked on the 26th day after infection (P < 0.001) and intestinal worm burdens on day 48 were greater (P < 0.001) in the infected lambs. Feed intake and liveweight gain were similar (P > 0.10) between control and infected lambs. Digestibility and flow of DM and N through the digestive tract were also unaffected (P > 0.10) by parasite infection. Despite a trend towards higher abomasal AA flux in the parasitised lambs (P < 0.10), apparent AA absorption from the small intestine and AA availability to other tissues were unaffected (P > 0.10) by infection. These results suggest that an established parasite infection had little effect on the intestinal absorption and availability of AA to other tissues in lambs fed fresh Lucerne.     

Performance of fattening cattle and lactating beef cows on diets high in chemically treated wheat straw and poultry litter

Three experiments were carried out to study the effect of chemical treatment on the nutritive value of wheat straw (WS) and the effect of diets containing such treated straw and poultry litter (PL) on the performance of fattening cattle and lactating beef cows. The chemical treatment consisted of treating half of the wheat straw with 60 kg sodium hydroxide/t and the other with 60 kg sulphuric acid/t, and then mixing the two to give “Celephos”. The digestibility coefficient of organic matter was 68.0 and 41.7 for “Celephos” and untreated straw, respectively.For a long term feeding trial, two mixtures were formulated: (a) including 23% WS and 19% PL; (b) including 30% chemically treated WS and 16% PL. A conventional high grain fattening diet (c) served as control. The metabolizable energy concentrations in the above diets were 2.37, 2.38 and 2.78 Mcal/kg DM. Protein content of the diets was regulated by PL or soya bean meal. Liveweight gain was 1059, 1137 and 1180 g/day, metabolizable energy conversion ratio to liveweight was 22.8, 20.7 and 20.0 Mcal/kg, and carcass gain was 565, 606 and 656 g/day for treatment groups (a), (b) and (c), respectively.In a third trial, lactating beef cows were fed on long straw or Celephos, PL and 1.5 kg grain per head per day. Intake of Celephos was 28% higher than that of untreated straw and milk output was 3 kg/day higher. This was reflected in an increase of 67 g/day in gain of suckled calves.     

Effects of feeding level and protein content of milk replacer on the performance of dairy herd replacements

It has been suggested that United Kingdom recommendations for feeding the neonatal calf (500 g milk replacer (MR)/day; 200-230 g CP/kg milk powder) are inadequate to sustain optimal growth rates in early life. The current study was undertaken with 153 high genetic merit, male and female Holstein-Friesian calves (PIN2000 = ￡48) born between September and March, with heifers reared and bred to calve at 24 months of age. Calves were allocated to one of four pre-weaning dietary treatments arranged in a 2 MR feeding level (5 v. 10 l/day) × 2 MR protein content (210 v. 270 g CP/kg dry matter (DM)) factorial design. MR was reconstituted at a rate of 120 g/l of water, throughout, and was offered via computerised automated milk feeders. Calves were introduced to pre-weaning diets at 5 days of age and weaned at day 56. During the first 56 days of life, calves offered 10 l MR/day had significantly higher liveweight gains (P < 0.001) than calves fed 5 l MR/day. No significant differences in liveweight gain were found between calves fed 210 g CP/kg DM MR and those fed 270 g CP/kg DM MR from birth to day 56. Differences in live weight and body size due to feeding level disappeared by day 90. Neither MR feeding level nor MR CP content affected age at first service or age at successful service, and with no milk production effects, the results indicate no post-weaning benefits of increased nutrition during the milk-feeding period in dairy heifers.     

Do supplements of Acacia mearnsii and grapeseed extracts alone or in combination alleviate metabolic nitrogen load and manure nitrogen emissions of lambs fed a high crude protein diet?

ABSTRACT

Diets excessive in crude protein (CP) are unfavourable in terms of metabolic and environmental load. Dietary phenols, often binding to dietary proteins, may alleviate these problems. In an experiment with 60 lambs (3.2 ± 1.6 months of age; 29.7 ± 5.1 kg body weight), kept in pairs, five diets were tested. A diet with 157 g CP/kg dry matter (DM) served as negative control. Four diets with on average 229 (225–233) g CP/kg DM remained either non-supplemented or were supplemented with 13 g/kg DM of Acacia mearnsii extract, grapeseed extract, or a combination of both (26 g extract/kg DM). The analysed concentrations of total extractable phenols were 7.1, 8.1, 14.3, 16.6 and 25.4 g/kg DM for low (CP^?) and high CP (CP⁺), and high CP with acacia (CP^+A), grapeseed (CP^+G) and acacia plus grapeseed (CP^+AG), respectively. Diets were fed for 10 weeks, and for 6 d faeces and urine were collected and subsequently stored as complete manure for 8 weeks. In blood plasma, phenol concentrations and activities of enzymes indicating liver and kidney stress were analysed. The CP⁺ diet increased apparent digestibility of N and its removal with the urine, with the expected increase in gaseous N emissions from the manure (13.5 vs 6.5 g/lamb per day during 8 weeks) compared to CP^?. However, no clear signs of metabolic stress were detected. Supplementing the extracts did not impair intake, growth performance and digestibility. Only the supplementation with both extracts decreased urinary N proportion of manure N, and the concomitant weak decline in gaseous emission from the manure was not significant. At least part of the phenols of both extracts seem to be bioavailable as their supplementation elevated blood plasma phenol concentrations by 15% to 40% compared to CP⁺. A combination of both extracts did not result in a further increase. Further studies have to identify the minimally effective dosage for reducing N emissions, which, at the same time, does not cause adverse side effects in performance.     

Effect of dietary cobalt supplementation on plasma and rumen metabolites in Mehraban lambs

Two experiments were conducted to study the effects of different levels of dietary cobalt on performance, plasma and rumen metabolites and nutrient digestibility in Mehraban male lambs. Experiment 1: 28, 8–9-month-old lambs were randomly divided into four groups. Animals were fed a basal diet containing 0.088 mg Co/kg DM and were supplied with 0 (control), 0.25, 0.50, or 1.00 mg Co/kg DM as reagent grade CoSO₄·7H₂O. The experiment lasted for 70 days. Experiment 2: four lambs from each group in Experiment 1 were randomly allocated to the individual metabolic crates to measure the effects of dietary Co on nutrient digestibility. Final body weight, average daily gain and gain efficiency were higher (p < 0.05) in the group supplemented with 0.50 mg Co/kg DM compared to other groups. Plasma glucose and vitamin B₁₂ concentrations increased (p < 0.05) at all levels of Co supplementation on day 68 of the experiment and for vitamin B₁₂ were higher (p < 0.05) at 0.50 and 1.00 mg Co/kg DM compared to 0.25 mg Co/kg DM. There was no significant difference among treatments for TVFA and ruminal fluid pH. Digestibility of dry matter, organic matter, crude protein and neutral detergent fiber increased (p < 0.05) by Co supplementation, but did not differ among Co supplied treatments. The obtained results showed that lambs fed the control diet containing 0.088 mg Co/kg DM had a reduced appetite and gained less than the supplemented animals, suggesting that the level of 0.088 mg Co/kg DM was inadequate for normal growth of Mehraban male lambs, and a total level of 0.58 mg Co/kg DM might be optimum level for enhancing performance.     

Energy and nitrogen balance,intake and growth rate of lambs fed on unwilted grass silages treated with a formaldehyde—Acid mixture or untreated

Wether lambs were fed on precision-chopped first-cut ryegrass silage ad libitum in an intake trial, and a maintenance and 1.5 times maintenance in balance trials.The untreated and treated silages had pH values of 4.72 and 4.40, mean dry matter (DM) contents of 176 and 184 g kg^?1 and mean gross energy (GE) contents of 18.8 and 19.0 MJ/kg DM, respectively.Mean digestibility coefficients of DM (0.787 and 0.783), organic matter (OM) (0.827 and 0.820) and GE (0.794 and 0.793), for the treated and untreated silages respectively, were high. The metabolisable energy (ME) contents of the untreated and treated silages were 12.52 and 12.76 MJ/kg DM at maintenance and 11.94 and 12.56 MJ/kg DM at 1.5 times maintenance, respectively. The mean efficiency of utilisation of ME of the untreated and treated silages was 0.65 and 0.66 for maintenance (k_m) and 0.34 ± 0.134 and 0.40 ± 0.069 for growth (k_g), respectively; the k_g values were lower than expected.Dry matter intakes of these silages when given ad libitum were 27.9 and 28.8 g/kg W per day and produced live weight gains of 129 and 140 g day^?1 for the untreated and treated silages, respectively. These gains were similar to predicted values for live weight gain only when the experimentally determined k_g and k_m values were substituted in the equation of the Agricultural Research Council (1980) used for calculating the daily metabolisable energy requirements for live weight gain.