Cereal Hay Research Articles

Effects of increasing days of exposure to prepartum transition diets on milk production and milk composition in dairy cows

To evaluate the effects of length of exposure to prepartum transition diets on milk yield, fat and protein production. Prospective cohort study. The number of days that the cows were fed the prepartum transition diets was the exposure of interest. Holstein and Holstein x Jersey cows (n = 1008) were enrolled. Diets given in the far-off dry period (from end of lactation until approximately 3 weeks before expected parturition) consisted of ad libitum access to perennial ryegrass pastures. Prepartum transition diets included perennial ryegrass pasture, ryegrass silage, cereal hay, grain, grain by-product, protein meals, BioChlor, sodium monensin, virginiamycin or tylosin, MgSO(4), trace elements and vitamins. On a dry matter basis, these contained 16.0% crude protein, 4.2% rumen undegradable protein, and 9.9 mJ metabolisable energy/kg. Diets provided an estimated metabolisable protein balance of 286 g/day and dietary cation anion difference of -150 meq/kg dry matter. Statistical models controlled for effects of herd, calving day, breed, age and gestation period. Increasing length of exposure to the prepartum transition diets significantly increased the 4.0% fat- and 3.2% protein-corrected milk yield and milk-protein yield as a linear and quadratic effect. The optimal duration of exposure to the prepartum transition diets was 25 days for fat- and protein-corrected milk production and 22 days for milk protein production. Milk-fat percentage decreased significantly and linearly with increasing exposure to the prepartum transition diets; however, milk-fat yield or milk-protein percentage did not vary significantly with duration of exposure to the diets. Increasing exposure to prepartum transition diets increased milk and milk-protein yields and decreased the milk fat-percentage, but not the milk-protein percentage or milk-fat yield.

Effect of supplementation with grain, hay or straw on the performance of weaner Merino sheep grazing old man (Atriplex nummularia) or river (Atriplex amnicola) saltbush

AbstractOld man saltbush (Atriplex nummularia) and river saltbush (A. amnicola) are widely used in commercial grazing systems on saline land in south‐western Australia. Three hypotheses were tested during a 3‐year study aimed at understanding the performance of weaner Merino sheep grazing saltbush‐based pastures. The first hypothesis, that young Merino sheep grazing river saltbush would be better able to maintain live weight, body condition and would grow more wool than sheep grazing old man saltbush, was not supported by the data. Across the 3 years of the study, sheep grazing old man saltbush lost significantly less live weight and grew more wool (proportionately 0·06) than sheep grazing river saltbush. Differences in animal performance were considered to be associated with differences between the plant species in in vitro digestibility, concentrations of fibre, sulphur and crude protein in the herbage and the architecture of the Atriplex plants. The second and third hypotheses concerned supplementation strategies for sheep grazing saltbush. Three supplements were offered, namely barley grain, cereal straw or cereal hay, at a rate that approximated to one‐third of the daily metabolizable energy requirements for maintenance of live weight. The performance of the sheep was higher when the grain supplement was offered but there was no effect of feeding roughage supplements compared to no supplementation. The findings suggested that the practice of feeding saltbush with adjacent crop stubbles is unlikely to be beneficial once any fallen grain has been consumed.

A review of the nutritional value of lupins for dairy cows

Australia is the world’s leading source of lupin grain, producing ~1 million tonnes annually, of which 30% is used by the domestic livestock industry and the rest is exported for use in animal diets, including dairy cows. The domestic dairy industry uses ~70 000 tonnes annually, mainly as a supplementary feed source in pasture-based systems. Although much published information exists on the nutritive value of lupins for dairy cows, it tends to be fragmented and, in some important instances, exists only in the form of reports or publications outside the mainstream scientific journals. This paper aims to present a critical assessment of the current knowledge regarding the nutritional value of lupins as a feed for dairy cows, and offers recommendations for future research. For cows grazing pasture or fed diets based on conserved pasture or cereal hay, the mean fractional response to lupin feeding was 0.53 kg milk/kg DM lupins, with a range of 0–0.97 kg/kg. The mean fractional forage substitution rate was 0.54 kg DM/kg lupins, and this appeared to be independent of the type of basal forage. In experiments using cows fed iso-nitrogenous and iso-energetic total mixed rations, substituting oilseed protein such as soybean meal with cracked lupin grain had no significant effects on yield of milk, fat, and protein, but it reduced milk protein concentration and had mixed effects on fat concentration. There were no significant differences in milk yield or in fat or protein concentration when lupins were substituted for other pulse grains such as faba beans or peas. Treatment of lupin grain with heat or formaldehyde reduced lupin protein degradability in the rumen, but was not shown to have consistent benefits over untreated lupins in terms of increased milk yield. Substitution of cereal grains with an equivalent weight of lupins in dairy concentrate rations generally resulted in increased yield of milk, fat, and protein, and a higher fat concentration. The higher yield responses in most cases could be explained on the basis of the higher metabolisable energy content of lupins compared with cereal grains, although the contribution from a potentially lower incidence of rumen lactic acidosis could not be discounted. Feeding Lupinus albus lupins to cows significantly increased the concentration of C18 : 1 in milk and reduced that of C12 : 0–C16 : 0, thus shifting the fatty acid profile of milk towards national dietary guidelines for improved cardiovascular health in human populations. Although the review lists some recommendations for improving the nutritive value of lupins, current commercially available cultivars possess characteristics that make them attractive as a feedstuff for dairy cows.

Effect of fibre supplementation on dag formation and flystrike in sheep grazing spring pastures

Sheep on spring pastures may scour excessively due to the low levels of neutral detergent fibre. Scouring leads to dag formation, which predisposes sheep to flystrike, particularly in the breech area, posing a considerable challenge to sheep producers. This trial was undertaken to test whether supplementing sheep on spring pasture with fibre would reduce diarrhoea and thereby reduce dag formation and flystrike. Four hundred first-lambing Merino ewes were randomly allocated to control (no fibre supplementation) and fibre treatment (ad libitum cereal hay or wheat straw supplementation) groups in a 2-paddock crossover trial, which was conducted from August through the spring flush to crutching in October. The bulk fecal egg counts of each group were no different at the start of the trial but the fibre group had a higher (P<0.05) fecal egg count than the control at crutching. Fecal egg count was not correlated with dag score. Fecal dry matter percentage was higher (P<0.05) in the fibre group but there was no difference in dag wet weight or dry matter percentage between the treatment groups. Dag scores of a sample of 100 sheep from each group were significantly (P<0.01) lower at crutching. There was no difference between the groups in the incidence of flystrike, however, there were significantly (P<0.001) more sheep with high dag scores (>3) in the control group than the fibre treatment group. These results indicate that the supplementation of spring pasture with low quality hay or straw can reduce dag formation by improving the consistency of feces and, thereby, reduce the number of sheep with dag scores greater than 3.

Differences in the chemical composition and digestibility of cereal hay and straw produced in a Mediterranean rainfall area of South Africa

Chemical composition and digestibility values were obtained to provide a database for accurate values of hay and straw types produced in the Western Cape area of South Africa. Straw and hay samples were collected from 10 different localities in the Swartland and Rûens areas of South Africa. Barley hay had the highest IVOMD value (753.2 g kg−1), followed by wheat (744.9 g kg−1), triticale (720.4 g kg−1) and oats (697.7 g kg−1). Wheat hay had the highest TDN value (670.7 g kg−1), with oats having the lowest value (627.5 g kg−1). Oats was higher in NDF (602.8 g kg−1) compared to the other hay types. ADF values of barley (297.9 g kg−1), oats (342.4 g kg−1) and triticale (323.0 g kg−1) differed significantly. Oat straw had a much higher IVOMD value (392.0 g kg−1) compared to the other straw types. Barley had the lowest IVOMD value (293.2 g kg−1). The TDN value of oats (444.8 g kg−1) was higher than for the other straw types. Barley straw had the highest NDF value (817.7 g kg−1), which differed from oats (781 2 g kg−1) and triticale (795.4 g kg−1). There were significant differences in the ash, CP, IVOMD, TDN and ADF contents of straw produced in the Swartland and Rûens areas. Ash, CP, IVOMD and ADF values of cereal straw samples were higher when produced in the Rûens. NDF values were higher in cereal straw samples from the Rûens, except for barley (from the Swartland), which had a higher NDF value. The TDN value of cereal straw was higher for the samples collected in the Rûens compared to those from the Swartland, although wheat and triticale showed higher TDN values when sampled in the Swartland. These differences should be taken into account when hay and straw from the different areas are used in formulating a balanced diet. This accentuates the importance of routine analysis of hay and cereal straw before use in diet formulations.

Effects of cereal grain, lupins-cereal grain or hay supplements on the intake and performance of grazing dairy cows

Summary. Three experiments of 5 weeks duration, using 32 Friesian cows per experiment, were conducted in northern Victoria during 1994–95. Experiment 1 was conducted during spring (October–November), experiment 2 was carried out in summer (January–February), and experiment 3 was in autumn (April–May). In each experiment, there was a pasture only treatment and 3 treatments in which 5 kg dry matter (DM)/cow of different supplements were offered in 2 equal feeds each day. The supplements were either pelleted cereal grain (75% barley and 25% wheat), pelleted mixed grains (50% lupins, 25% barley, 25% wheat) or hay. The hay used in experiment 1 was made from lucerne (Medicago sativa), while that used in experiments 2 and 3 originated from irrigated annual and perennial pastures, respectively. Cows strip-grazed irrigated pasture at a herbage allowance of about 30 kg DM/cow.day in each experiment. There were 4 cows per treatment and treatments were replicated twice. All supplements significantly (P<0.05) increased milk production. The lupins–cereal grain supplement resulted in the greatest response and the hay the smallest response, both in terms of absolute level of production and the marginal return to additional total DM consumed (1.4, 1.7 and 0.9 kg of extra milk for each additional kg DM of total intake associated with the cereal grain, lupins–cereal grain and hay supplement treatments, respectively). However, the marginal response to each kg of a supplement varied (P<0.05) with the time of the year. There were no differences between supplements in spring whilst in summer and autumn, the cereal grain and lupins–cereal grain supplements were better (P<0.05) than hay. Milk solids yield responded in a manner similar to milk yield. This was principally due to the fact that none of the supplements affected (P>0.05) milk protein content and, although milk fat content was reduced (P<0.05) by both concentrate supplements, the effects were not biologically large (a difference of about 0.05 percentage units). The cereal grain and lupins–cereal grain supplements also improved (P<0.05) the body condition of cows relative to those that were unsupplemented or were supplemented with hay. Levels of substitution were similar across types of supplement, averaging 0.28 kg DM reduction in pasture intake for each kg DM of supplement eaten. It was concluded that, at low pasture allowances (high stocking rates) with moderate supplementation, large differences in substitution between readily fermentable concentrate supplements, such as cereal grain or lupins–cereal grain, and hay are unlikely. Hence, responses in milk will largely be based on the energy content of the supplement. At higher pasture allowances and/or higher levels of supplementary feeding, variations in substitution will probably play an important role in determining the responses observed.

An analysis of soil organic matter dynamics in relation to management, erosion and yield of wheat in long-term crop rotation plots

We examined the influence of management on soil organic matter (SOM) dynamics and yield of wheat grain in semiarid Chernozemic and humid Gray Luvisolic soils. The Century model was tested with data obtained from long-term research plots cropped to wheat (Triticum aestivum L.) monoculture and cereal-hay (CH). Century simulated changes in soil organic-C (OC) and organic-N (ON) within 10% of actual measurements taken over decades. Our analysis indicated that management and soil erosion affected the time required for SOM to achieve new steady-state level (Tst). Tst ranged between 12 yr under wheat and 46 yr under CH cropping. Increasing the SOM content of degraded soils to new steady-state level appears to increase grain yield between 86 kg ha−1 and 840 kg ha−1.Wheat-fallow (WF) rotation plots receiving <10 kg N ha−1 yr−1, and with erosion >13.6 t ha−1 yr−1 degraded SOM. The average long-term yield of wheat grain (including new high yielding varieties) was maintained at <910 kg ha−1 yr−1 under degraded SOM content. Well-fertilized continuous wheat (CW) and CH rotation plots with erosion <4 t ha−1 yr−1 aggraded SOM content, and maintained the long-term average grain yield at >1290 kg ha−1 yr−1. Sustained OC levels were attained by returning 1030 kg C ha−1 yr−1 as plant residue (roots + aboveground) and keeping soil erosion ≤12.8 t ha−1 yr−1. Sustainable crop production systems need to consider SOM dynamics and erosion as factors limiting grain yield even after introducing genetically improved wheat varieties. Key words: Management, organic matter, erosion, dynamics, yield, manure, nitrogen, tillage, steady-state

The influence of management on soil loss and yield of wheat in Chernozemic and Luvisolic soils

The effects of management practices on erosion and crop productivity for different agro-ecosystems in Canada are largely unknown. A study was conducted to examine the effects of management on soil loss and wheat yield in long-term research plots, established in western Canada. Soil erosion was measured using the 137Cs technique. Under conventional tillage, topsoil was lost at a rate of 2–37 t ha−1 yr−1. Equivalent loss in topsoil thickness ranged between 0.02 and 0.28 cm yr−1. Soil losses were highest in 2–yr wheat–fallow crop rotations. Continuous wheat, 5–yr cereal–hay rotations, and plots amended with manure reduced soil losses and maintained thicker topsoils. At Ellerslie, Alberta, there was no measurable soil loss from a Black Chernozemic cropped to continuous barley under zero tillage. Decrease in annual wheat yield averaged 106 kg ha−1 cm−1 topsoil loss in the Brown Chernozemic and 117 kg ha−1 cm−1 topsoil loss in the Gray Luvisol. Key words: Management, erosion, topsoil, manure, yield

Nutrient intake of horses in thoroughbred and standardbred stables.

Twenty-five Thoroughbred (TB) and 25 Standardbred (SB) stables were visited to determine their feeding practices. The ingredients of the main feed of the day for a mature gelding of average size in full training were weighted at each stable. Nutrient content of diets was calculated using published data for the individual ingredients. Results are expressed as mean +/- sd. The estimated body weight of TB horses was 493 +/- 34 kg and 437 +/- 32 kg for SB horses. There was considerable variation in diet composition and nutrient intake between stables. The TB trainers fed 11.0 +/- 2.4 kg and SB trainers 11.8 +/- 2.5 kg per day. The concentrate component of the diet weighed 7.8 +/- 1.6 and 7.7 +/- 2.3 kg for TB and SB stables, respectively, and the roughage component for TB horses 3.3 +/- 1.4 and SB horses 4.1 +/- 1.4 kg per day. The digestible energy intake of horses at TB stables was 129 +/- 29 MJ per day and at SB stables 132 +/- 31 MJ per day. Crude protein intake of TB horses was 1452 +/- 363 g and SB horses 1442 +/- 338 g per day. There were differences in some feeding practices at TB and SB stables. Standardbred trainers fed more roughage than TB trainers. Standardbred trainers fed chaffed lucerne (alfalfa) and cereal hays as the major roughage, whereas TB trainers fed more hay. The major hay type fed by TB trainers was lucerne, whereas many SB trainers preferred clover hay. Both trainers fed oats as the major grain, but TB trainers fed slightly more maize (corn) than SB trainers.(ABSTRACT TRUNCATED AT 250 WORDS)

Milk production by dairy cows fed legume grains or barley grain with or without urea as supplements to a cereal hay based diet

Milk production and composition was determined in Holstein-Friesian cows fed either 3.5 or 7.0 kg dry matter (DM) daily of lupin grain, pea grain, faba bean grain or barley grain with or without 1.5% added urea, as supplements to an oaten hay based diet. All the grains were hammermilled. Daily yields of milk (L), fat (kg) and protein (kg) were significantly (P<0.05) higher for cows fed lupin (20.0, 0.81, 0.57), pea (18.9, 0.80, 0.56) and faba bean (18.9, 0.79,0.55) grains compared with those of cows fed barley grain with (17.8, 0.73, 0.51) or without (18.0, 0.71, 0.52) urea. Yields of milk (L), fat (kg) and protein (kg) and milk protein content (g/kg) were significantly (P<0.05) higher when 7.0 kg DM (19.5, 0.80, 0.57, 29.6) compared with 3.5 kg DM (18.0,0.73,0.51,29.0) of grain was fed. There were no significant differences between treatments in hay DM intake by cows fed 3.5 kg DM of grain daily. A significantly (P<0.05) higher milk fat production per unit DM intake was recorded for cows fed legume compared with barley grain. There were generally higher returns above grain cost for cows fed legume compared with barley grain and for cows fed 4 kg compared to 8 kg daily of grain. It was concluded that it was more economical to feed 3.5 kg DM of legume grain compared with 3.5 kg DM of barley grain, with or without urea, as supplements for cows offered cereal hay in early lactation. However, the economics of feeding 7.0 kg DM of legume grain compared with 7.0 kg DM of barley grain and 7.0 kg DM compared with 3.5 kg DM of grain will depend on the costs of relative changes in hay intake associated with these practices.

Fermentation of hammermilled barley, lupin, pea and faba bean grain in the rumen of dairy cows

Four lactating Friesian cows fitted with rumen cannulae were used in a 4 × 4 Latin square design experiment and fed on oaten hay ad libitum. Hammermilled lupin, pea, faba bean or barley grain, calculated to provide 70% of the total ration dry matter, was given twice daily via the rumen cannula. Rumen liquor was sampled at 0, 1, 2, 3, 4, 6, 8, 10 and 12 h after the grain was given at 08 00 h, and pH and the concentrations of ammonia-nitrogen, lactic, acetic, propionic and butyric acids measured. The rate of degradation of modified-acid-detergent fibre (MADF) was determined in milled oaten hay incubated in nylon bags in the rumen. When the cows were given hammermilled barley grain, rumen pH declined to a minimum value of 5.4, and from three to six hours after the grain was given rumen pH was significantly ( P < 0.05) lower than when the cows were given the legume grains. Rumen pH was maintained above 6.0 when the cows were given hammermilled lupin or faba bean grain. Rumen pH was generally reflected in rumen lactic acid concentration. Rumen ammonia-nitrogen concentration was significantly ( P < 0.05) higher at 0, 3, 4, 5, 6 and 8 h after the legume grains were given than after the barley grain. Differences between diets in the concentration of total volatile fatty acids and the proportions of volatile fatty acids were generally not significant. The rate of degradation of MADF in oaten hay tended to be less when the cows were given hammermilled barley or pea grain than when they were given lupin grain. Mean dry matter intake of oaten hay was significantly ( P < 0.05) higher when the cows were given the legume grains rather than the barley grain. It was concluded that giving high levels of hammermilled legume grains (especially lupins) rather than barley grain to dairy cows will result in rumen pH values and ammonia-nitrogen concentrations that are unlikely to cause significant depressions in the rate of fibre digestion or intake of cereal hay.

OXALATE CONCENTRATION IN FEEDS AND ITS METABOLISM BY PONIES

Total oxalate and calcium determinations were made in 200 feed samples. Legume hays contained more oxalate than legume-grass, grass (including brome and timothy), native grass and cereal hays (P &lt; 0.05). Grass, native and cereal hays contained low calcium and low to moderate oxalate concentrations. Based on molar ratios and the assumption of preferential binding of calcium by oxalate, it was estimated that about 25% of calcium in legume and legume-grass hays could be bound by oxalate. Similarly, oxalate might bind 38–44% of the calcium contained in native grass and cereal hays and would exacerbate the low calcium content of these hays. Only one hay, a kochia, had oxalate concentrations (3.2%) known to cause acute toxicity in livestock. Oxalate concentration was positively correlated to calcium concentration (r = 0.69). Chopped alfalfa, oat, brome, and slough hay and pelleted alfalfa, oat and barley hays were fed to ponies in two separate Latin square experiments. Apparent oxalate digestibilities were determined to be 48–88%. Cereal hays had the highest apparent oxalate digestibilities in both trials (73–88%) (P &lt; 0.05). Key words: Oxalate, calcium, forages, ponies

NUTRIENT UTILIZATION OF PELLETED AND UNPELLETED FORAGES BY PONIES

Two separate digestion studies using mature ponies evaluated nutrient utilization of unpelleted alfalfa, brome, slough and oat hays and pelleted alfalfa, oat and barley hays grown in Saskatchewan. Alfalfa and cereal hays provided between 2.33 and 2.58 Mcal digestible energy (DE)/kg dry matter (DM). Brome and slough hay supplied 2.13 and 1.75 Mcal DE/kg DM, respectively. Alfalfa hay had a higher digestible crude protein content than other forages tested within each trial. Calcium (Ca) availability was lower from oat hay than other unpelleted forages (P &lt; 0.05). Ponies were in negative Ca balance when either oat or barley hay pellets were fed; this occurred through an apparent increase in urinary Ca excretion. Phosphorus (P) balances were negative when slough hay or cereal hays were fed. Oxalate and phytate determinations were made in forages and concentrations of 0.26–1.3% oxalate and 0.06–0.44% phytate were obtained. Voluntary intakes of alfalfa and brome hay by ponies were higher than oat or slough hays (P &lt; 0.05). Pelleted alfalfa hay was eaten in larger amounts than oat or barley hay pellets (P &lt; 0.05). Of the forages tested, alfalfa hay was considered to be the best hay for supplying nutrients for horses. Cereal hays provide a good source of energy and protein for mature equids but would require macromineral supplementation. Key words: Forages, pony, nutrient utilization

Growth responses of young Merino wethers to ad libitum feeding of oat grain mixed with either lupin seed or a urea solution

Groups of 10 Merino weaners or hoggets were offered ad libitum 1 of 5 grain mixtures: oats alone (9.1% crude protein, CP), oats mixed with lupins (CP 12 or 15%), and oats sprayed with a urea solution to increase total nitrogen to an equivalent of 12 or 15% CP. In experiment 1, each grain mixture was fed with 10% milled cereal hay to sheep in pens for 98 days; in experiment 2 the sheep grazed wheat stubble for 84 days. In experiment 1, the liveweight gains of weaners and hoggets fed the lupin or urea mixtures were greater by 53-69% and 58-120�/o, respectively, than the daily 9.4 and 54.1 g/head gained on oats alone (P&lt; 0.05). In experiment 2, liveweight gains of sheep fed these mixtures were, with 1 exception, greater by 95-1 54% than the 69.0 and 58.3 g/head gained daily by sheep fed oats alone (P&lt; 0.05). Addition of urea to oats at the higher level (15% CP) tended to depress intake and liveweight gain, compared with the 12% CP level, and the effect was greater among hoggets. Wool production paralleled feed intake and liveweight gain. It is concluded that the daily growth rates of 90 to 130 g/head resulting from treatment of oats with up to 1.5% urea can be similar to those from oat-lupin mixes of equivalent CP (daily 85-150 g/head).

Nutrient losses in cereal and pasture hays stored in three types of hay packages in the open in two environments

Cereal and pasture hays, cut at the same site, were packaged into medium-sized round bales, large round bales and stacks. Halfthe number of each hay type and of each hay package were stored in the open for up to 15 months in a 500 mm rainfall area and half were transported to and stored for up to 15 months in a 1000 mm rainfall area. Densities of the pasture hay packages were within the manufacturers' specified ranges but those of the cereal hay packages were lower. Medium-sized round bales were less dense than large round bales and weathered more than large round bales and stacks after 10 and 15 months storage. Cereal hay packages deteriorated more than pasture hay packages with long-term storage. Medium-sized round bales lost more dry matter than large round bales after storage over the winter and more digestible dry matter over this period and after long-term storage. They also lost more crude protein than large round bales when stored over the first summer and over the following winter. It was economic to store all packages in the open over the first summer. It was uneconomic to store medium-sized round bales in the open over the following winter, while storage of large round bales and stacks was economic. For long-term storage, it was uneconomic to store any of the hay packages in the open, and storage under cover would have to be considered.

Assessment of dry-matter yield from grain yield in the West African Savannah Zone

Crop residues, consisting of cereal stovers and hays made from the vegetative parts of grain legumes, are important dry-season feeds for ruminant livestock in the Savannah Zone of West Africa (van Raay, 1975; McCown, Haaland &amp; de Haan, 1979; Jahnke, 1982). With the increasing demand on land to produce more crops and animal products, traditional systems are under pressure. There is need for a reliable means to quantify the supply of feed from various sources and to monitor the type, quantity and quality of crop residue available to livestock.

Feeding hay-based diets deficient in protein to dairy cows during early lactation

In two experiments, 87 Friesian cows were fed diets of moderate (141%), moderate-low (117%), or low protein content (9.2%) for the first 12 weeks of lactation. These diets contained 5 kg dry matter (DM)/cow.d of either rolled lupins, a 1:1 mixture of rolled lupins and rolled barley, or rolled barley together with cereal hay ad libitum. During weeks 13-24 of lactation, all cows were fed 2 5 kg DM/cow.d of rolled barley as a supplement to cereal hay ad libitum in experiment 1, and pasture ad libitum in experiment 2. All cows were fed cereal hay or hay plus grain during weeks 25-36 of the experiments. Mean estimated intakes of hay DM during the first 12 weeks of lactation were 14.6, 14.8 and 11.9 kg/cow.d in experiment 1, and 15.7, 14.8 and 12.8 kg/cow.d in experiment 2, for cows fed diets of moderate, moderate-low, and low protein content, respectively. Significant differences ( P &lt; 0.05) in liveweight were recorded during the first 12 weeks of lactation. Liveweight differences between groups were evident for a larger part of the lactation in experiment 1 than in experiment 2. The mean daily yields of milk during the first 12 weeks of lactation in both experiments were higher (P&lt;0.00 1) for cows fed diets of moderate (21.9 and 23.5 litres) or moderate-low (20.7 and 22.1 litres) protein content than those of cows fed diets of low protein content (1 6.4 and 15 5 litres). Milk yields for weeks 13-24 and 25-36 did not differ (P&gt; 0.05) between treatment groups in either experiment; milk composition did not differ (P&gt;0.05) between treatment groups in any 12-week period in experiment 1 or 2. Cows fed low protein diets were less efficient in the use of feed or body reserves for milk production than cows fed diets of moderate or moderate-low protein content. Economic data indicate that it is currently profitable to ensure that the protein content of hay-grain diets fed during early lactation is at least 14% of DM irrespective of likely feeding regime over the remainder of the lactation.

The effect of abomasal infusion of urea on nitrogen retention in goats

There is evidence that a large volume of saliva containing a significant quantity of urea is poured into the rumen, and also that blood urea is diffused into the rumen through the ruminal epithelium (Houpt, 1959; Weston &amp; Hogan, 1967). Egan (1965) reported that, with sheep fed a low protein cereal hay, cellulose digestion in the rumen was increased by abomasal urea infusion. Furthermore, the utilization of recycled urea nitrogen has been investigated in sheep (McIntyre, 1971) and cattle (Vercoe, 1969) using the intraruminal and intravenous infusion techniques. The objective of the present experiment was to determine whether or not the abomasal administration of urea to adult goats fed a low quality hay would influence the nitrogen retention in the body.

FEEDING VALUE OF FORAGE AS FED TO STEERS AND ESTIMATED BY IN VITRO DIGESTION

The digestibility and intake of 23 hays and three silages were determined in two experiments with Hereford steers averaging 215 kg at the start of the test. Each forage was fed in a chopped (4 to 6 cm) form as the sole diet to two steers for 56 days. Voluntary intake and body weight gain during the fourth through the seventh week were used as measures of animal performance. Digestibility was determined by collecting all the feces during the eighth week, allowing for a three-day lag between intake and excretion. The forages included grass, legume and cereal hays, and cereal and legume cereal silages produced under a wide range of conditions. The concentration of in vitro digestible organic matter (DOM) in the forage was highly correlated with gain (r = 0.57 and 0.86) and intake of digestible energy (DE) (r = 0.62 and 0.89). The voluntary intake by the steers was comparable with that by sheep in earlier experiments at two other locations, when the intake was based on metabolic body size, and on similar in vitro DOM or in vivo DE concentrations in the forage. Differences in intake between experiments followed the same pattern as feed allowance in excess of intake, but the effect of in vitro DOM or in vivo DE content on intake was apparently the same in each experiment. This supported the theory that regressions of DE intake by sheep on in vitro DOM content of forage will serve as a measure of the feeding value, providing that appropriate experimental conditions are maintained.

The effect of delaying the introduction of concentrates on the summer milk production of hay-fed dairy cows

From November 23, 1965, concentrates were introduced successively at two-week intervals to five treatment groups of grade Friesian cows that were being fed a basal ration of cereal hay in the paddock. The yield of milk, butterfat, solids-not-fat, and protein rose significantly as the supplements were introduced but almost no significant effect of concentrate feeding was observed on the weekly percentage composition tests of the milk. A comparison of the total covariance corrected yield results for the experimental period from November 23, 1965, to March 15, 1966, showed that the group of cows receiving concentrates throughout produced 30 per cent more milk, and 29 per cent more solids-not-fat, but only 24 per cent more protein and butterfat than the group receiving concentrates from January 18, 1966. However, the additional milk production would be uneconomic where milk is purchased on a butterfat basis.