Summary. We tested the hypothesis that liveweight gain per hectare could be doubled in beef steers grazing irrigated annual pastures by increasing stocking rate from 2.5 to 5.0 steers/ha and supplementing the heavier stocked treatments with maize silage offered at either 2.4 or 5.6 kg dry matter/steer. day to replicated groups of 4 steers. During an average period on feed of 172 days, liveweight gain was substantially increased, from 245 kg/ha to either 464 or 576 kg/ha, when maize silage was fed to steers at 2064 or 4816 kg dry matter/ha, in association with an increase in stocking rate from 2.5 to 5.0 steers/ha. However, such production systems increased the chance of feed shortages, particularly in exceptionally wet winters such as the one experienced in the experiment. Increasing the rate of supplementary feeding without increasing stocking rate may not be economically viable. Other strategies, such as lot feeding steers, were also tested. Diets where maize silage constituted either 46% dry matter (with the balance of the diet comprising wheat grain, cottonseed meal, urea, bentonite, vitamins and minerals) or 97% dry matter (with the balance of the diet comprising urea, vitamins and minerals) led to steers achieving liveweight gain of 1.34 and 0.93 kg/steer. day respectively. Carcasses from steers eating maize silage fed at pasture or maize silage as a component of lot-fed diets had at least as adequate fat cover and as good eating quality as carcasses from steers grazing at 2.5 steers/ha.

Four combinations of maize silage and artificially dried red clover were fed consecutively to adult wether sheep ad libitum and at a level designed to maintain liveweight. On a dry matter (DM) basis, the diets contained silage and clover at ratios 1 :0, 2: 1, 1:2, and 0:1. A fifth diet contained maize silage plus urea (as 1% of the silage DM). Energy, nitrogen (N), and carbon balances were measured at both feeding levels and while fasting. The maize silage contained 11 g N and 41 1 g cell wall organic matter/kg DM; corresponding values for red clover hay were 37 and 290 g. Energy and protein metabolisms were monitored on the 5 diets and were related to dietary N content. Feed intake and digestibility increased with the proportion of clover in the diet and, hence, with increasing dietary N content. Energy losses from methane and heat production did not differ among diets, whereas urine energy losses were smallest, and therefore, efficiencies of utilisation of metabolisable energy (ME) greatest, on the silage-only and silage + urea diets. Greater urinary N losses on the diets of 1 : 2 silage: clover and clover-only led to lower N balances at the same apparently digested N intake on these 2 diets. There were positive associative effects between the silage and clover for voluntary feed consumption; digestibilities of energy, N, and cell wall organic matter; and energy and N balances. A ratio of ME to digestible energy of 0.81 underestimated the content of ME in silage by 0.5 MJ/kg DM, yet overestimated it in clover by 0.4 MJ/kg DM. The ME value of the silage + urea diet (11.6 MJ/kg DM) was one of the highest reported in sheep for maize silage using indirect calorimetry.

Dairy cows in mid lactation grazed paspalum-dominant perennial pastures and were offered either crushed wheat or maize silage at 0, 25, 50, or 75 MJ metabolisable energy/cow.day. Another herd was offered maize silage ad libitum. Milk yield and composition, liveweight and body condition, and pasture intakes were monitored over 8 weeks during summer. Cow performance was recorded for another 3 weeks when all cows were supplemented with the same feedlot ration. Samples of pastures before and after grazing, supplement, rumen fluid, and faeces were collected for chemical analyses. Linear regressions were used to calculate mean milk responses and rates of pasture substitution for the 2 supplement types. Yields of milk and milk solids increased with level of supplement fed (with 1 exception) and were higher in cows fed wheat at the same level of supplemental energy. However, cows fed maize silage achieved higher body condition scores. On average, cows supplemented with wheat and maize silage, respectively, produced 0.72 and 0.38 kg extra milk/kg supplement (DM), and they substituted pasture at the rate of 0.87 and 1 .O1 kg pasture DM/kg supplement DM. Low pasture quality (117 g crude protein/kg DM and 59.5% in vitro digestibility) was considered the main cause of high levels of pasture substitution and poor milk responses to maize silage feeding. Cows fed 6.8 kg DM/cow.day of maize silage had very low rumen ammonia-N and faecal N concentrations. It was concluded that additional N should be included with maize silage when fed to cows grazing low quality perennial pastures, even with feeding levels as low as 2 or 3 kg DM/cow.day.

Dairy cows in early lactation grazed irrigated perennial pastures in early spring and were offered 7-8 kg maize silage DM/day, either in the morning or throughout the entire day and night. Another group of cows with rumen fistulae were pen-fed annual pasture of similar quality and offered maize silage, again, in the morning only or throughout the day and night. Rumen retention time, diet digestibility, and excretion of maize grains were measured during the pen-feeding trial, as well as the rate of disappearance of feed samples from nylon bags placed in the rumen of each cow. Diurnal variations in rumen pH, total volatile fatty acids, and ammonia concentrations were monitored every 2 h. Intakes of grazed pasture, and diurnal variations in rumen pH and ammonia, were measured in the grazing cows. Milk yield and milk composition, and changes in liveweight and body condition (in the grazing cows only), were also monitored.Although time of feeding maize silage influenced rumen fermentation patterns in both pen-fed and grazing cows, it had little effect on feed intake and utilisation, or on milk production. This was attributed to the low levels of rumen-degradable starch in the maize silage, which would have had minimal influence on rumen cellulolytic activity. Therefore, unlike supplements of cereal grains, for which twice-daily feeding is recommended, maize silage need only be offered once daily without adversely affecting the performance of cows grazing high quality spring perennial pastures.

Dairy cows in early lactation grazed irrigated annual pastures during 14 weeks in autumn and winter. They were grazed for either 2 or 6 h each day and then restricted to a feedpad and offered ad libitum maize silage. Other cows were fed 1 of 2 diets while in yards: a feedlot diet based on cereal grain, maize silage, and protein supplement; a mixture of conserved legume and maize silage. Feed intakes and cow performance were monitored. Cows in metabolism cages were fed the feedlot diet with various combinations of red clover and maize silage. Digestibility and rate of disappearance of test feeds from nylon bags were measured in the metabolism trials. Rumen samples were analysed for pH, ammonia, and volatile fatty acids. Dietary constituents were evaluated in vitro and in vivo using sheep.The cows on the feedlot diet recorded the highest DM intakes and the highest liveweight gain, and initially produced the most milk and milk protein. Their milk yields eventually fell to levels similar to those of the grazing cows. Cow performance was poorest on the pasture silage-maize silage mixture, and this treatment was discontinued after only 8 weeks. The poor performance was partly attributed to reduced silage quality from heat damage during ensiling the pasture. Supplementing red clover with increasing levels of maize silage did not influence digestibility but reduced DM intakes and cow performance.Cows grazing for 2 h/day produced 1-2 L/day less milk, and lost more weight, than cows grazing for 6 h/day; their rumen ammonia fell below critical levels. The grazing of high-clover pastures between morning and afternoon milking, combined with maize silage supplementation, is convenient and sustains high milk yields during early lactation.

Dairy cows in mid lactation were pen-fed ad libitum maize silage, ad libitum maize greenchop, or restricted maize greenchop. A cottonseed meal supplement was also fed at 20% forage maize DM. The maize greenchop was harvested daily over 5 weeks during February and March. Both forms of forage maize were fed to sheep in metabolism cages.Digestibility was always higher with maize silage. Digestibility of maize greenchop improved with time until 34-36% DM, after which it declined, this being associated with changes in structural carbohydrates in the crop. Cows fed maize silage produced more milk and gained less weight than cows fed both greenchop diets.In a concurrent field trial, cows grazed irrigated perennial pastures in late summer and were offered 7-8 kg DM/day of the silage or greenchop. Additional cows were allocated extra pasture with no supplement. Treatment differences in milk production and liveweight change were not significant. There were differences in rumen metabolism between diets in both pen-fed and grazed cows; rumen ammonia levels increased during the day in cows fed maize silage, but they decreased or remained constant when maize greenchop was fed. There was more maize grain in greenchop at physiological maturity than in silage, and this could have contributed to observed differences in performance and rumen metabolism.The low rumen ammonia levels, and the fact that forage maize was higher in energy than the pasture on offer, suggest that milk response would have improved with the inclusion of a rumen-degradable nitrogen source such as urea with the forage maize supplements.

Dairy cows in early lactation were fed a maize-silage-based supplement at either 3 or 8 kg DM/cow.day, while grazing irrigated perennial pastures at 45 or 30 kg pasture DM/cow.day. The supplement consisted of maize silage, alone or with 16% DM replaced by cottonseed meal. A fifth group grazed at the higher pasture allocation with no supplements. Milk yield and composition, liveweight and body condition, and pasture intake were monitored over 10 weeks during late spring-early summer. Samples of pre- and post-grazed pasture, supplement, rumen fluid, and faeces were collected for chemical analyses.Supplemention increased total feed intake and milk yield of grazing cows, except at the higher level of silage without cottonseed meal. From data on nitrogen content of the grazed pasture and the supplement, together with rumen ammonia concentrations, it was concluded that low dietary protein levels limited milk yield in cows supplemented with 8 kg maize silage DM/day without the additional cottonseed meal. Liveweight and body condition score increases were greater in supplemented animals, while their rumen volatile fatty acid profiles suggested greater partitioning of nutrients towards lipogenesis in body tissue. Pasture was substituted at the rate of 0.67 kg DM for every kg maize silage DM consumed.

The influence of season and management system on the productivity of Friesian cows in a Mediterranean climate was assessed. Intakes of food and water and milk yields were measured in 154 cows over 2·5 years while intensively managed in yards giving access to shelter (free stalls) or that were fully exposed to solar radiation (open lots). Food quality was also monitored to permit estimates of the efficiency of utilization of metabolizable energy for milk production over fortnightly periods.The highest milk yields and energetic efficiencies were recorded during spring. Energy intakes were highest but energetic efficiencies were lowest during winter. Cows consumed the least food during summer and autumn and drank the most water during summer. The only significant effect of management system was for water intake, which was higher in the open lots than in the free stalls. There was evidence of heat stress in summer and cold stress in winter, but there appeared to be little benefit with milk yields through the provision of shelter.

Eighty-eight Friesian cows and heifers were fed in two trials on four complete diets based on maize silage and lucerne hay during early lactation. The four diets varied in grain content from 0 to 500 g kg−1 dry matter (DM), but were isonitrogenous at 25 g N kg−1 DM. In the second trial, 46 of these animals were monitored for their entire lactation. Voluntary feed intake, yields of milk and milk solids and changes in liveweight and body condition (the latter in the second trial only) were measured. Digestibility of organic matter, concentrations of rumen ammonia and volatile fatty acids and excretion of whole grains in faeces were also measured during early lactation. The dietary effect was partitioned into that attributable to linear or quadratic influences.

Six lactating cows, 6 dry cows and 6 wether sheep were fed ad libitum on diets of maize silage, maize silage plus lucerne, or maize silage plus lucerne plus wheat. Faeces and urine collections allowed for the determination of digestibility of dry matter, organic matter and nitrogen, and balances of nitrogen and water.

Cattle and buffalo play an important role in the agriculture of South East Asia, providing both milk and meat and also traction for ploughing and transport. The native breeds vary considerably in their characteristics, not only in their inherent qualities but in their response to varying systems of management, some very primitive. Improvement is clearly possible by cross-breeding, but it appears that this is most likely to be achieved within existing native breeds, than by introducing exotic ones developed to thrive under very different circumstances.

The chemical constituents of carcasses from 105 serially slaughtered bulls comprising Madura, Ongole, Bali, Grati (Friesian cross) and swamp buffalo were determined from ground rib joints from all animals and ground carcass sides from 48 bulls. Other carcass quality attributes were also assessed on each carcass. The bulls had previously been fed diets containing 85 or 30% concentrate for up to 280 days. Huxley's allometric equation was used in its logarithmic form as the basis for covariance analyses of the data. Rates of fattening on the 85% concentrate.diet, in decreasing order, were buffalo and Bali, Madura and Ongole, then Grati. There was a genotype by diet interaction for carcass protein, ether extract and energy in that the Madura bulls produced fatter carcasses on the high-concentrate but the leanest carcasses on the high-roughage diets. Buffalo carcasses were low scoring with small rib eye areas and high levels of subcutaneous fat, whereas the highest-scoring carcasses were those from Madura and Bali bulls. Genotype differences in daily carcass protein retention are discussed in relation to rate of maturing and also dietary influences.

Four maize silage/grain diets were incubated in nylon bags for up to 72 h in the rumen of non-lactating cows. The test samples were frozen and either finely ground or coarsely chopped. The cows were fed basal rations containing either 0 or 50% grain. Increasing grain content in the test samples was linearly associated with rate of dry matter disappearance (k) and also with DM disappearance after 48 h in sacco. With k there was a significant interaction between processing of the test samples (grinding vs. chopping) and basal ration of the cows, but the ranking of the test samples was not influenced by either processing or basal ration. Rate of DM disappearance was also closely associated with DM digestibility measured in sheep (r = 0.97; P < 0.01), but not with dietary metabolizable energy content as calculated from productivity data of lactating cows (r = 0.75; P < 0.10). The possibility of interactions with other dietary nutrients would reduce the potential of nylon bag studies for assessing feeding value of mixed diets for milk production.

The weights of carcass and non-carcass components were recorded in 105 serially slaughtered bulls comprising Madura, Ongole, Bali, Grati (Friesian cross) and swamp buffaloes that had been fed diets containing 85 or 30% concentrate for up to 280 days. Huxley's allometric equation was used in its logarithmic form as the basis for covariance analyses of the data. Dressing percentages, in decreasing order, were Madura, Bali, Ongole, Grati and buffalo, and were inversely related to weights of gut contents, head, feet, hide and internal offal (pluck, liver, spleen and kidney and empty gut). Weights of abdominal fat depots were lowest in the Grati bulls. There were both genetic and dietary influences on the proportional development of components of the alimentary tract.

Diets containing 85% (high concentrate) or 30% (high roughage) concentrate were individually fed for 280 or 224 days, respectively, to young Madura, Ongole, Bali, Grati (or Friesian crossbred) and swamp buffalo bulls. Each feeding trial was divided into early or late periods to study the effects of approaching maturity on growth and feed use. The digestibility of dietary nutrients, the balances of nitrogen, phosphorus and calcium, and the metabolizability of the gross energy of the high-roughage diet were measured. Growth rates in decreasing order were Grati, Ongole, buffalo, Bali and Madura. Genotype differences in growth were generally the result of variations in intake rather than in feed use. There were genotype x trial interactions in feed intake and liveweight gain during the latter part of each trial in that on the high-concentrate diet, the performance of Ongole and Madura bulls was poorer than that of the Grati and buffalo bulls whereas performances were similar on the high-roughage diet. Dietary metabolizable energy contents were estimated to be 11.8 and 9.5 MJ kg-1 dry matter for the two diets, respectively. Liveweights were higher and more divergent between genotypes at the end of the high-concentrate feeding period. As they were also higher than those reported for mature animals maintained under traditional village management, it was concluded that indigenous Indonesian large ruminants would respond to improved feeding and management. However, their feedlot performances would be unlikely to equal that of dairy crossbred cattle.

Rice straw was fed ad libitum to Indonesian Zebu (Ongole) and swamp buffalo bulls. The straw was fed either untreated or treated with 4% NaOH for 24 h, and with or without a Leucaena (L. leucocephala) supplement. Elephant grass (Pennisetum puvpuveum) was fed as a control diet. Alkali treatment improved digestibility of dietary nutrients and the metabolizability of dietary energy, and was associated with an increase in the movement of water and digesta through the gut. However, it also depressed appetite by 25-30%, and this may have been related to the high pH of both the diet and the rumen following feeding. Intake of the alkali-treated rice straw, when fed with Leucaena, was increased by up to 30%, whereas that of untreated rice straw was depressed by 10-20%. In the Leucaena-supplemented animals, increases were observed in rate of passage of digesta, balances of dietary nutrients (nitrogen, phosphorus and calcium) and levels of rumen metabolites. The animals offered elephant grass had similar intakes to those of animals receiving untreated, unsupplemented rice straw. The Ongoles and buffaloes responded in a similar manner to the various dietary treatments and, apart from differences in water metabolism, urinary urea-nitrogen excretion and rate of passage of digesta, the nutritional physiology of the two animal species was very similar.