Methods of improving the utilization of cereal straw by ruminants. III. A note on the effect of ensiling straw treated with urea

Straw treated with urea was offered to lambs either freshly prepared (EN₀) or after ensiling with urea for 30 days (EN₃₀). The lambs also received 10 g dry matter (DM) of shredded, artificially dried grass per day per kg of metabolic liveweight. Ensiling straw significantly increased its intake from 32 to 41 g DM per day per kg of metabolic liveweight, and its DM digestibility from 375 to 450 g per kg.     

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.     

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

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.     

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.     

Utilization of alkali-treated grain. 2. Utilization by steers of diets based on hay or straw and mixed with either NaOH-treated or rolled barley

In the first of three experiments, Hereford cross steers were fed ad libitum from 325 kg to slaughter at 425 kg on diets containing 50% hay and 50% rolled or NaOH-treated (30 g/kg) barley. Liveweight gain and food conversion ratios were similar for the two groups (1.24 vs. 1.42 kg/day; 7.0 vs. 7.0 kg dry matter intake/kg gain, respectively). Dry matter and organic matter digestibility was significantly higher (P < 0.01) when the diet contained rolled, rather than NaOH-treated, barley. There were no significant differences in fibre digestibility (51.2 vs. 59.1%, respectively).In the second experiment, the optimum level of NaOH was determined for the treatment of barley when given with hay. The level of NaOH required to achieve a digestibility in whole barley similar to rolled barley was 40 g NaOH/kg, i.e., approximately 10 g/kg more than when NaOH-treated barley formed the sole component of the diet. Dry matter and organic matter digestibility increased linearly as the level of NaOH applied increased (P < 0.05) and tended to peak at 40 g NaOH/kg barley. Starch digestibility also increased linearly (P < 0.001). Fibre digestibility did not vary significantly between treatments.In the third experiment, the voluntary intake of straw by steers given rolled or NaOH-treated barley at two levels of supplementation was determined. The intake of straw was slightly, but not significantly, greater when NaOH-treated rather than rolled barley was used. The digestibility of dry matter, organic matter, starch and fibre was not significantly affected by method of cereal treatment. No problems of animal health arose throughout the three experiments.     

Growth performance and carcass characteristics of Awassi lambs and Shami goat kids fed yeast culture in their finishing diet

Two experiments were completed to examine effects of inclusion of a yeast culture (YC) to a diet based on barley grain and wheat straw on digestibility, growth and meat traits of Awassi lambs and Shami goat kids. Experiment 1 studied effects of YC on apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and N balance in sheep, while experiment 2 studied effects on growth performance and carcass composition of lambs and kids. The same diet was used in both experiments and the YC was added to the diet of treated groups at the level of 12.6 kg YC/tonne of diet. Addition of YC had no effect on apparent digestibility of DM, CP and NDF, but it increased (P<0.05) digestibility of OM and ADF. No differences occurred in N intake, output or retention. Addition of YC did not affect growth rate, or DM intake, in both lambs and kids. YC supplementation to lambs reduced hot carcass weight, cold dressing proportion and total muscle/bone ratio, but increased empty digestive tract weight. There were no changes in back fat thickness, intermuscular fat of the leg muscle, and weights and proportions of carcass cuts. Measures of kids’ carcass characteristics and quality also did not differ. Only cuts of leg and shoulder differed (P<0.05) when calculated as a proportion of the whole carcass cut. Results show that YC supplementation increased digestibility with no effect on growth, feed intake or feed conversion ratio of fattening lambs and kids. However, YC supplementation reduced meat/bone ratio and tissue protein content, but increased fat content in carcasses of fattening Awassi lambs, but not in fattened Shami kids.     

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.     

Supplementation of alkali-treated rice straw

Goats were fed rice straw treated with 0,4 or 8% NaOH, dehydrated palm oil mill effluent (POME) at 20 or 30 g/kg liveweight (LW)/day and Leucaena at 5 or 10 g dry matter (DM)/kg LW/day in Experiment 1, and rice straw treated with 4% NaOH or 4% NH₄OH, POME at 30 g/kg LW/day and either Napier grass or Leucaena at 10 g DM/kg LW/day in Experiment 2. Treatment with 4% NaOH promoted the highest intake of rice straw. 10·3 and 12·4 g DM/kg LW/day respectively in Experiments 1 and 2. Feeding Leucaena at 10 g DM/kg LW/day significantly increased total intake (36·0 g DM/kg LW/day) and DM digestibility (59·0%) in Experiment 1, and supported a LW gain of 63 g/day in Experiment 2. It is concluded that diets comprising 25% NaOH-straw, 50% POME and 25% Leucaena permitted dietary nutrients to be used efficiently and maximised the inclusion of by-products.     

Factors affecting degradation of barley straw in sacco and microbial activity in the rumen of cows fed fibre-rich diets: III. The amount of supplemental energy

A basic diet composed of 76.2% untreated barley straw +23.8% grass hay was given to three non-lactating cows at 90% of ad libitum intake; the diet was supplemented with fishmeal to make the ration up to 12% protein on dry matter basis, a mineral–vitamin mixture and either 1.5 kg; 3.0 kg or 4.5 kg of rolled barley/cow×day in a Latin Square design. The inclusion of rolled barley affected the degradability of DM, OM and individual components of the cell wall of barley straw incubated in nylon bags for up to 72 h. The higher the energy level of supplementation, the lower the digestion of the cell wall components. The amount of starch influenced rumen pH, ammonia and VFAs concentrations, ATP and protozoal numbers, but no treatment effect could be detected upon the outflow rate of liquid or particulate phases. The ATP and DNA concentrations found inside the nylon bags suggest the presence of an inactive or less active population towards the substrate after 24 h of incubation.     

Ammonia and sodium hydroxide treatment of wheat straw in diets for fattening steers

The effects of treating Neepawa wheat straw with anhydrous ammonia (35 kg t^?1), sodium hydroxide (50 kg t^?1) and pelleting were evaluated in two experiments. The diets consisted of 51% rolled barley, 40% straw, 4% rapeseed meal, 2% tallow, plus minerals and a vitamin supplement. Straw was treated as follows: (1) shredded into 2.0-cm lengths; (2) shredded into 0.64-cm lengths and pelleted; (3) ammoniated and shredded; (4) ammoniated and pelleted; (5) sodium hydroxide and pelleted; (6) ammoniated, sodium hydroxide and pelleted.Apparent digestibility was measured with six steers per treatment. Pelleting had no effect on organic matter (OM) digestibility, but decreased neutral detergent fibre (NDF) and cellulose digestion. Respective increases for OM and NDF digestibility following chemical treatment of the straw were as follows: ammoniation — 15 and 17%; sodium hydroxide — 4 and 13%.The six diets were given to 144 Hereford steers (240 kg) for 92 days in the second experiment. Feed consumption ranged from 8.51 to 10.39 kg day^?1 for diets 1 and 4, and body weight gains ranged from 0.83 to 1.26 kg day^?1 for diets 1 and 6, respectively. Respective increases for intake, gain and feed efficiency compared to untreated shredded straw were as follows: pelleting — 11, 34 and 17%; ammoniation — 12, 36 and 17%. Sodium hydroxide treatment prior to pelleting improved intake, gain and feed efficiency by 5, 10 and 5%, respectively. There was no evidence of additive effects between ammoniation and either pelleting or alkali treatment, though treatment with sodium hydroxide prior to pelleting did result in the highest gains and feed efficiency.     

The effect of ammoniation on the intake and nutritive value of straw

Studies were conducted to compare the increases in dry matter digestibility (DMD) in vitro and in vivo and to determine the metabolisable energy (ME) value of straw ammoniated at ambient temperature. Two stacks of straw sealed with polyethylene were allowed to react with 3% (w/w) anhydrous NH₃ for 30 and 56 days, respectively. Both DMD in vitro and nitrogen tests were carried out over an eight-week period subsequent to opening the stacks. Digestibility in vivo was measured with 12 wether lambs. The non-treated and ammoniated straws were given ad libitum, with a supplement of either ground barley or a lamb concentrate which contained 16% crude protein (CP).There was a mean increase of 15 percentage units in DMD in vitro for the ammoniated straw irrespective of whether it was treated for 30 or 56 days. The corresponding increase in mean DMD in vivo was 14.2 units. The CP content of the straw was increased from 3.1 to 7.6%. The increase in DMD in vitro and total N content was maintained throughout the sampling period. Approximately 58% of the anhydrous NH₃ added to the straw appeared to have been irreversibly “bound” to the straw. The ME values for the ammoniated straw were 6.78 and 7.49 MJ/kg when the straw was supplemented with either barley or the lamb concentrate, respectively. Straw ammoniation had a marked effect on intake. The overall increase in intake was 70% for the treated compared with the non-treated material.     

Digestion of organic matter and nitrogen in ammoniated barley straw

Barley straw, either treated with anhydrous ammonia (40 g/kg for 28 days) or untreated, was chaffed and given to sheep in an intake and digestibility trial, or was ground and incubated in nylon bags in the rumen of sheep fed on lucerne or untreated or ammoniated straw.Ammoniation increased the N content from 2.45 to 10.63 g/kg dry matter (DM). Of the increment, 67% was retained in water-soluble form and 11.5% was in the cell wall organic matter (CWOM). The water-soluble N appeared to be retained by sheep as well as urea-N given with untreated straw; digestibility coefficients obtained in vivo, and by nylon bag incubation, suggested that N in CWOM was largely unavailable.Ammonia treatment increased the potential digestibility (measured by nylon bag incubation) of DM and CWOM by 23 and 29%, respectively. Digestibility in vivo of OM increased from 0.42 to 0.60 and of CWOM from 0.48 to 0.67. Intake of ammoniated straw increased over the 23-day feeding period, while that of untreated straw given with or without urea was constant or declined.     

Effects of lowering crude protein supply alone or in a combination with essential oils on productivity,rumen function and nutrient utilization in dairy cows

Lowering dietary protein concentration is known to decrease urinary nitrogen (N) losses and increase milk N efficiency in dairy cows, but it may negatively affect animal productivity. Plant-derived essential oils (EO) may alleviate these negative effects by improving the efficiency of rumen fermentation in cows fed reduced feed protein diets. The experiment was conducted to investigate the effects of lowering crude protein (CP) supply alone or in a combination with an EO product on feed intake, milk production and composition, rumen fermentation, total tract digestibility and N utilization in dairy cows. Twenty-one Holstein cows were used in a replicated 3 × 3 Latin square design experiment. Each period consisted of 14 days for adaptation and 14 days for data collection and sampling. Cows were randomly assigned to one of three experimental diets: a 165 g/kg CP diet (control), a 155 g/kg CP diet (LCP) and LCP supplemented with 35 g/day per cow EO (LCPEO). The dry matter (DM) intake was decreased by LCP and LCPEO compared with the control; there was no effect of EO on DM intake. Milk yield and composition and feed efficiency were similar among treatments. Ruminal pH, lactate, ammonia and volatile fatty acids concentrations were not affected by treatment, except increased valerate concentration by LCPEO compared with LCP. The supplementation of EO tended to decrease protozoal counts. The LCP and LCPEO increased total tract digestibility of DM and organic matter and decreased CP digestibility compared with the control. Supplementation with EO did not affect total tract digestibility of dietary nutrients compared with the control or LCP. The LCP and LCPEO decreased urinary and fecal N excretions and increased milk N efficiency; nitrogen losses were not affected by EO. In this study, lowering dietary CP by 10 g/kg decreased urinary and fecal N excretion without affecting productivity. The supplementation of EO to LCP had only minor effects on rumen fermentation and did not affect productivity, digestibility and N excretion in lactating dairy cows.     

Effect of ruminally protected fat on in vitro fermentation and apparent nutrient digestibility in buffaloes (Bubalus bubalis)

Experiments were conducted to evaluate effects of supplementation of calcium salts of long chain fatty acids (Ca-LCFA) as a rumen inert fat (PF) on in vitro fermentation and apparent nutrient digestion in adult buffaloes fed wheat straw based diets. For the in vitro fermentation study, five total mixed rations (TMR) consisting of a concentrate mixture (CM), green Sorghum bicolor, WS and supplemented without (C) or with 30 g/kg dry matter (DM) rice bran fatty acid oil (RBO) (30 RBO) or 20 g/kg RBO + 10 g/kg PF (20 RBO/10 PF) or 10 g/kg RBO + 20 g/kg PF (10 RBO/20 PF) or 30 g/kg PF in the DM in the ratio of 340:50:580:30 were prepared. The in vitro DM degradability (IVDMD), TN, trichloro acetic acid precipitable N (TCA-N), non-protein N (NPN) and ammonia N (NH₃-N) were similar among groups. Within the fat supplemented groups, total volatile fatty acid (TVFA) concentration increased linearly (P=0.025) with PF supplementation. Apparent nutrient digestibility was determined on 20 adult buffaloes divided into five equal groups fed CM supplemented without (C) or with 300 g RBO (30 RBO) or 200 g RBO + 100 g PF (20 RBO/10 PF) or 100 g RBO + 200 g PF (10 RBO/20 PF) or 300 g PF (30 PF) along with limited green S. bicolor and WS maintaining forage: concentrate ratio of 650:350. Fat supplementation had no effect on the DM intake and apparent digestibilities of DM, organic matter (OM), crude protein (CP), total carbohydrate (TCHO) and neutral detergent fiber (aNDF). Within fat supplemented groups, inclusion of PF increased digestibilities of DM, OM, ether extract (EE), TCHO, aNDF and ADF. Supplemental fat also increased the digestible energy (DE) and metabolizable energy (ME) content of the diet, which also increased linearly with PF supplementation. All buffaloes were in positive N, Ca and P balances. We conclude that 200–300 g supplemental PF in the form of Ca-LCFA can be included in straw based diets fed to buffaloes to increase its energy density without adversely affecting DM intake and digestibility.     

Effects of oilseed meal and grain-urea supplements fed infrequently on digestion in sheep: 1. Low quality grass hay diets

An experiment examined intake, growth response and rumen digestion of young sheep fed ad libitum low quality grass hay alone or supplemented with approximately isonitrogenous amounts of barley grain and urea (Bar/N), safflower meal (SAF) or linseed meal (LIN) provided at 3 days intervals. Supplements comprised 13–20% of total DM intake. Sheep fed grass hay alone consumed 60.2 g DM/kg LW^0.75/day of hay and an estimated 6.09 MJ metabolizable energy (ME)/day, and were in liveweight (LW) maintenance. Hay intake was decreased (P<0.05) by the Bar/N supplement with a substitution rate of 0.9, but was not changed by the oilseed meal supplements. Each of the supplements increased (P<0.05) estimated ME intake to a similar extent, but LW gain and wool growth were lower (P<0.05) in sheep supplemented with Bar/N than those supplemented with LIN. Rumen degradabilities of the SAF and LIN CP were estimated to be 0.72 and 0.62, respectively. Rumen ammonia concentrations in sheep fed hay alone (average 97 mg NH₃/l) were expected to be adequate for microbial activity. Fractional outflow rate (FOR) of liquid from the rumen measured with Co-EDTA (mean 0.109 h⁻¹) was greater than that of Cr-mordanted supplements (mean 0.056 h⁻¹), which was in turn greater than the FOR of Cr-mordanted hay (mean 0.031 h⁻¹). Diet did not affect these FOR. Supplemented sheep accommodated increased DM intake on Day 1 of the 3 day supplementation cycle by increasing rumen digesta load rather than by increasing rate of passage of digesta. Results show that the LW gain of young sheep fed low quality hay was increased more by either oilseed meal than by equivalent amounts of barley grain/urea supplement, apparently due to more efficient utilization of ME for LW gain.     

How does the suppression of energy supplementation affect herbage intake,performance and parasitism in lactating saddle mares?

Agroecology opens up new perspectives for the design of sustainable farming systems by using the stimulation of natural processes to reduce the inputs needed for production. In horse farming systems, the challenge is to maximize the proportion of forages in the diet, and to develop alternatives to synthetic chemical drugs for controlling gastrointestinal nematodes. Lactating saddle mares, with high nutritional requirements, are commonly supplemented with concentrates at pasture, although the influence of energy supplementation on voluntary intake, performance and immune response against parasites has not yet been quantified. In a 4-month study, 16 lactating mares experimentally infected with cyathostome larvae either received a daily supplement of barley (60% of energy requirements for lactation) or were non-supplemented. The mares were rotationally grazed on permanent pastures over three vegetation cycles. All the mares met their energy requirements and maintained their body condition score higher than 3. In both treatments, they produced foals with a satisfying growth rate (cycle 1: 1293 g/day; cycle 2: 1029 g/day; cycle 3: 559 g/day) and conformation (according to measurements of height at withers and cannon bone width at 11 months). Parasite egg excretion by mares increased in both groups during the grazing season (from 150 to 2011 epg), independently of whether they were supplemented or not. This suggests that energy supplementation did not improve mare ability to regulate parasite burden. Under unlimited herbage conditions, grass dry matter intake by supplemented mares remained stable around 22.6 g DM/kg LW per day (i.e. 13.5 kg DM/al per day), whereas non-supplemented mares increased voluntary intake from 22.6 to 28.0 g DM/kg LW per day (13.5 to 17.2 kg DM/al per day) between mid-June and the end of August. Hence total digestible dry matter intake and net energy intake did not significantly differ between supplemented and non-supplemented mares during the second and third cycles. In conclusion, supplementing lactating mares at pasture should not be systematic because their adaptive capacities enable to increase herbage intake and ensure foal growth. Further research is needed to determine the herbage allowance threshold below which supplementation is required.     

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.     

Supplementation of isonitrogenous oil seed cakes in cactus (Opuntia ficus-indica)–tef straw (Eragrostis tef) based feeding of Tigray Highland sheep

The experiment was conducted at Maichew Agricultural Technical Vocational Education and Training College, Ethiopia. Twenty four male yearling Tigray Highland sheep with mean body weight (BW) of 21 ± 2.6 kg (mean ± S.D.) were used to investigate the effect of different protein sources on feed intake, nutrient digestibility, BW change and carcass parameters in a study comprising of 90 days feeding trial, followed by 7 days of digestibility trial and evaluation of carcass parameters. Six individually fed animals were used per treatment in a randomized complete block design. The treatments consisted of ad libitum feeding of tef (Eragrostis tef) straw plus 172 g dry matter (DM) of cactus (Opuntia ficus-indica) pear (T1, control) and supplementation with 145 g DM cotton seed cake (CSC) (T2), 195 g DM noug seed cake (NSC) (T3) or 149 g DM peanut cake (PNC) (T4) per head per day. The quantity of the supplements was set to supply 62.5 g crude protein (CP). Tef straw DM intake was depressed (P<0.01) as the result of NSC supplementation. Sheep supplemented with CSC and PNC had higher (P<0.001) total DM intake than the control and NSC supplemented ones. Supplementation with NSC and PNC also resulted in higher (P<0.01) apparent digestibility of DM and OM compared to the control treatment. Supplementation with CSC and PNC resulted in better daily BW gain (P<0.001), feed conversion efficiency (FCE) and dressed carcass weight (P<0.01) compared to the non-supplemented diet. Dressing percentage on slaughter weight base was higher (P<0.01) in supplemented sheep than in the non-supplemented ones. Supplementation with PNC also promoted higher (P<0.05) rib-eye muscle area than in the non-supplemented ones. It was concluded that supplementation with 145 g DM CSC and 149 g DM PNC resulted in better feed intake, BW gain and carcass traits in cactus–tef straw based feeding of sheep.     

Intake, digestibility, rumen fermentation and performance of beef cattle fed diets based on whole-crop wheat or barley harvested at two cutting heights relative to maize silage or ad libitum concentrates

This experiment aimed to quantify the relative intake, digestibility, rumen fermentation, performance and carcass characteristics of beef cattle fed diets based on good quality whole-crop wheat and barley silages, each harvested at two cutting heights, and to rank these relative to good quality maize silage and an ad libitum concentrates-based diet. Ninety beef steers, initial live-weight 438 ± 31.0 kg, were allocated to one of the following dietary treatments in a randomised complete block design: maize silage (MS), whole-crop wheat harvested at a normal cutting height (WCW) (stubble height 0.12 m) or an elevated cutting height (HCW) (stubble height 0.29 m), whole-crop barley harvested at a normal cutting height (WCB) (stubble height 0.13 m) or an elevated cutting height (HCB) (stubble height 0.30 m), each being supplemented with 3 kg concentrates/head/day, and ad libitum concentrates (ALC) supplemented with 5 kg grass silage/head/day for the duration of the 160-day study. Mean dry matter (DM) of the maize silage, whole-crop wheat, head-cut wheat, whole-crop barley and head-cut barley was 301, 488, 520, 491 and 499 g/kg, respectively. There were no differences in total DM intake among treatments, or in rumen fermentation characteristics (except ammonia), or in DM digestibility among the forage-based treatments. Neutral detergent fibre digestibility was lower (P<0.05) for whole-crop wheat than head-cut barley, and starch digestibility was lower (P<0.05) for whole-crop barley and head-cut barley than maize silage. Steers fed ALC had a higher carcass gain (P<0.001) and carcass weight (P<0.05) than all other treatments, but there were no differences between any of the forage-based treatments. Steers fed MS had a better feed conversion efficiency (FCE) than those on WCW or WCB (P<0.05) but were similar to HCW and HCB. The FCE was better for ALC versus any of the other treatments, particularly compared to WCW or WCB (P<0.001). Subcutaneous fat from steers fed ALC was more yellow (P<0.01) than that from steers fed the other treatments. Neither intake nor performance were altered by raising the cutting height of cereals or by replacing whole-crop wheat by barley. However, head-cut cereals numerically favoured DM intake, carcass gain and feed conversion efficiency values nearer to that of maize than whole-crop cereal silages. Ad libitum concentrates supported superior levels of growth by steers compared to all other treatments.     

Effects of replacing grass silage with maize silages differing in inclusion level and maturity on the performance,meat quality and concentrate-sparing effect of beef cattle

The effects of maturity of maize at harvest, level of inclusion and potential interactions on the performance, carcass composition, meat quality and potential concentrate-sparing effect when offered to finishing beef cattle were studied. Two maize silages were ensiled that had dry matter (DM) concentrations of 217 and 304 g/kg and starch concentrations of 55 and 258 g/kg DM, respectively. Grass silage was offered as the sole forage supplemented with either 4 or 8 kg concentrate/steer daily or in addition with one of the two maize silages at a ratio 0.5 : 0.5, on a DM basis, maize silage : grass silage supplemented with 4 kg concentrate daily. The two maize silages were also offered as the sole forage supplemented with 4 kg concentrate/steer daily. The forages were offered ad libitum. The six diets were offered to 72 steers (initial live weight 522 s.d. 23.5 kg) for 146 days. There were significant interactions (P < 0.05) between maize maturity and inclusion level for food intake, fibre digestibility and daily gain. For the grass silage supplemented with 4 or 8 kg concentrate, and the maize silages with DM concentrations of 217 and 304 g/kg offered as 0.5 or 1.0 of the forage component of the diet, total DM intakes were 8.3, 9.8, 8.9, 8.2, 9.2 and 9.8 kg DM/day (s.e. 0.27); live-weight gains were 0.74, 1.17, 0.86, 0.71, 0.88 and 1.03 kg/day (s.e. 0.057); and carcass gains were 0.48, 0.73, 0.56, 0.46, 0.56 and 0.63 kg/day (s.e. 0.037), respectively. Increasing the level of concentrate (offered with grass silage), maize maturity and level of maize inclusion reduced (P < 0.05) fat b* (yellowness). The potential daily concentrate-sparing effect, as determined by carcass gain, for the maize silages with DM concentrations of 217 and 304 g/kg offered as 0.5 and 1.0 of the forage component of the diet were 1.3, −0.3, 1.3 and 2.4 kg fresh weight, respectively. It is concluded that the response, in animal performance, including maize silage is dependent on the stage of maturity and level of inclusion in the diet. Maize silage with a DM of 304 g/kg offered ad libitum increased carcass gain by 31%, because of a combination of increased metabolizable energy (ME) intake and improved efficiency of utilization of ME, and produced carcasses with whiter fat.