THE EFFECT OF INCLUDING DRIED GRASS IN THE SUPPLEMENT GIVEN TO LACTATING COWS AT PASTURE

An investigation into the effect of including dried grass in the supplement given to dairy cows at pasture is reported. Supplements containing 0, 50 and 100% dried grass were used in the investigation which was carried out in two parts. In the first part 12 high-yielding cows with unrestricted access to pasture were used in an experiment with a change over design to assess the effects of feeding 5 kg/day of each supplement on milk yield and composition. In the second part 8 steers, housed in stalls and given cut herbage from the same sward as that grazed hy the cows, were used in a change over experiment to assess the effects of the three supplements on herhage and total DM intake. No significant differences in milk yield between supplements were ohtained, the mean yields being 23·9, 24·5 and 23·9 kg/day for the supplements containing 0, 50 and 100% dried grass, respectively. Milk composition was also not significantly affected by including dried grass in the supplement. In the indoor feeding trial using the steers, the addition of 3·5 kg DM from the supplement resulted in an increase in total DM intake of only 1·3 kg/day. There was no significant difference hetween supplements on herbage and total DM intake.     

THE INFLUENCE OF SUPPLEMENTARY FEEDING ON THE HERBAGE INTAKE AND GRAZING BEHAVIOUR OF DRY COWS

The herbage intake and grazing behaviour of 4 dry cows on autumn grass receiving 2, 4, 6 or 8 kg concentrates/day, was assessed in a 4×4 Latin Square experiment. Total OM intake increased from 11±5 kg/day with 2 kg concentrates to 13±6 kg/day with 8 kg concentrates. The average supplementary effect was 0±46 kg increase in OM intake/kg OM fed as concentrates. Minutes per day spent grazing decreased from 495 with 2 kg concentrates to 359 with 8 kg. The mean decline was 22 min./kg concentrates or 28 min./kg OM in concentrates eaten. Herbage was eaten at an average rate of 47 min./kg OM.     

THE EFFECT OF SUPPLEMENTARY BARLEY UPON GROWTH AND EFFICIENCY OF FOOD CONVERSION IN CALVES KEPT AT HIGH GRAZING INTENSITY

Three groups of Hereford × Friesian steer calves, bom in early January 1969, were strip-grazed on eqoal areas of a sward of S321 perennial ryegrass from May to September inclusive, and received kibbled barley at the rate of nil, 3/4% or 1 1/2% of liveweight per day. Adjustments were made to the number of animals per group in order to maintain the same high grazing intensity (defined as 8 cm stubble height in grazed areas) on all treatments. The animals receiving supplementary barley gained weight at a rate 17–19% higher than the controls, but there was no significant difference in growth rate between the high and low levels of supplementation. The effficiency of conversion of barley was only 5–12 kg per animal liveweight gain/100 kg barley OM. The high level of supplementation resulted in an increase in stocking rate of 36 % over that of the control group, and an increase in liveweight gain per unit area of land grazed of 63%. The additional liveweight gain due to supplements, expressed per unit area of land grazed, was relatively constant at 21–24 kg liveweight gain/ 100 kg barley OM consumed.     

Sodium fertilizer application to pasture. 2. Effects on dairy cow production and behaviour

Fifty-four lactaling dairy cows were grazed for 24 weeks on pasture receiving 0 (Nil), 32 (Low) or 64 (High) kg Na ha^-1 yr^-1 and with (+) or without (-) 100g NaHCO₃ buffer included in a maize gluten concentrate supplement. Cattle grazed the Na-fertilized pasture to a lower height, particularly in the High treatment. Cows grazing pasture with Na fertilizer produced more milk, and milk fat concentration increased in direct proportion to amount of Na fertilizer applied and with NaHCO₃. This increase was greatest in early season. Milk protein concentration was not affected by Na fertilizer application or NaHCO₃ buffer addition. Milk lactose concentration was increased by Na fertilizer application but not by NaHCO₃ supplementation. Cows in the Na-applied treatments gained more live weight but there was no effect of treatment on condition score change. Grazing time and drinking frequency increased linearly with increasing pasture Na. Ruminating time and biting rate were similar at the Low and High treatments and greater than the Nil treatment. NaHCO₃, supplementation increased drinking frequency and decreased the rate of concentrate intake. Cow reproductive performance was not significantly affected by Na fertilizer application. During the residual period, cows that had previously grazed the Na-fertilized pasture had reduced milk fat and protein contents.     

The effects of offering a range of forage and concentrate supplements on milk production and dry matter intake of grazing dairy cows

An experiment was undertaken to examine the effect of supplement type on herbage intake, total dry matter (DM) intake, animal performance and nitrogen utilization with grazing dairy cows. Twenty‐four spring‐calving dairy cows were allocated to one of six treatments in a partially balanced changeover design with five periods of four weeks. The six treatments were no supplement (NONE), or supplementation with either grass silage (GS), whole‐crop wheat silage (WS), maize silage (MS), rapidly degradable concentrate (RC) or slowly degradable concentrate (SC). Cows were rotationally grazed with a mean herbage allowance of 20·5 kg DM per cow per day, measured above 4 cm. Forage supplements were offered for approximately 2 h immediately after each morning milking, with cows on NONE, RC and SC treatments returning to the grazing paddock immediately after milking. Cows on treatment MS had a significantly higher supplement DM intake than the other treatments but a significantly lower grass DM intake than the other treatments, resulting in no significant difference in total DM intake when compared with cows on treatments WS, RC and SC. Concentrate type had no significant effect on herbage intake, milk yield, milk composition or yield of milk components. The yield of milk fat and milk protein was significantly higher on treatments MS, RC and SC compared with treatments NONE, GS and WS. The results indicate that despite a relatively high substitution rate, maize silage can be a useful supplement for the grazing dairy cow.     

OBSERVATIONS ON THE UTILIZATION OF GRASS GRAZED BY YOUNG BEEF CATTLE WITH AND WITHOUT BARLEY SUPPLEMENTATION

A field trial was carried out in which 3 groups of cattle were grazed on a paddock system with and without supplementary barley. The cattle were 6 months old when turned out to grass and were each fed 4 lb/day of barley for one week to prevent any adverse effect from an abrupt change of diet. The trial began on 14 May and continued until 8 October. The mean liveweight gain obtained on the unsupplemented grass was only 0·97 lb/day up to 20 August and owing to the poor growth of the animals a supplement of 4 lb barley/head/day was then introduced. The daily liveweight gain for the remainder of the trial was 1·94 lb. When a supplement of 4 lb barley was provided throughout the trial the mean daily liveweight gain was 1·61 lb. When barley was fed ad lib . intake averaged 12·3 lb/head/day throughout the trial and the mean daily gain was 2·45 lb.
Indoor digestibility and nitrogen retention trials were carried out. The starch equivalents of diets on the three treatments were 63·7, 68·3 and 69·5, respectively. The respective mean daily intakes of dry matter were 11·2, 11·9 and 11·8 lb, and the mean daily retentions of N were 35·0, 35·8 and 33·6g. These results indicate that although the grass was of good nutritive value the poor performance of the animals on grass alone was mainly due to their inability to graze sufficient grass.     

A COMPARISON BETWEEN SPRING AND AUTUMN PASTURE FOR BEEF CATTLE AT EQUAL GRAZING PRESSURES

Two comparisons between spring and autumn pasture for beef cattle were made. Animals used in all comparisons were of similar breed and weight and were subjected to the same feeding regime for 6–8 weeks before turn-out. The pastures were grazed on an equal grazing pressure basis between season comparisons. The pastures received similar rates of fertilizer N between seasons and had similar lengths of rest period for regrowth. Intakes of digestible OM were greater per unit of metabolic liveweight in spring than in autumn. Daily liveweight gains in spring were high, being 1·09 and 1·37 kg (2·4 lb and 3·0 lb), but were lower from autumn pasture at 0·98 and 0·71 kg (2·2 lb and 1·6 lb). Weather was implicated as a factor affecting daily gain from autumn pasture. Greater herbage yields in spring supported 42 and 204 more grazing days per ha which together with the greater gains per animal supported 80–120% more liveweight gain/ha.     

Silage and milk production: a comparison between barley and dried sugar-beet pulp as silage supplements

Two grass silages made from perennial ryegrass, and with D-values of 0·216 and 0·255, were offered ad libitum to 18 Ayrshire cows in two feeding experiments. On the control treatment the silages were supplemented with soybean meal only, and on the other two treatments with equal weights of DM from either barley or dried molassed sugar-beet pulp plus the same weight of soya as on the control treatment. The daily intakes of silage DM were not significantly different on the barley and beet-pulp treatments, and, on average, the intake of silage DM was reduced by 0·24 and 0·20 kg by feeding 1 kg barley and beet pulp DM respectively.
The daily milk yields were not significantly different on the barley and beet-pulp treatments with mean values of 19·2 and 19·2 kg per cow respectively compared with 17·2 kg on the control treatment. On the barley and beet-pulp treatments the fat, SNF, CP and lactose concentrations in the milk and the live weights of the cows were not significantly different. It is concluded that the barley and beet pulp had similar feeding values and replacement rates when used as supplements with grass silage, and that the two feeds were interchangeable on an equal DM basis.     

The effects of sward characteristics and supplement type on the herbage intake and milk production of summer-calving cows

High (H; 27 350 m^?1:) or low (L. 13 300 m-¹) tiller density perennial ryegrass swards were created in the mid- and late grazing season by imposing different sward heights in the spring. Summer-calving cows then grazed these swards from 6 June to 2 September 1992 and were offered 5 kg fresh weight hd^?1 d^?1 of either a barley (S) or a molassed sugar beet pulp (F) based supplement. The factorial combination of sward and supplement types resulted in four experimental swards being grazed by thirteen Holstein/Friesian cows each. Supplement F contained more crude fibre (110 vs. 58 g kg^?1) and less metabolizable energy [12–5 vs. 13–2 MJ kg^?1 dry matter (DM)] than supplement S. Herbage on the H sward contained more metabolizable energy (11–9 vs. 104 MJ kg^?1 DM) and crude protein (232 vs. 205 g kg^?1 DM), had fewer rejected areas f 16–5 vs. 26–9%) and a higher live-dead tiller ratio (4–6 vs. 2–1) than that on the L sward. Sward, but not supplement type, significantly affected the intake of grazed herbage (P<0–001). On average, the herbage intakes of cows grazing II swards were higher than for L swards (14–5 vs. 11 6kg DM d^?1) and those of cows on the S and F supplements were 12–6 and 13–5 kg DM d^?1 respectively. Averaged over the grazing period, sward and supplement had no significant effects on milk yield, milk composition or yield of constituents. When expressed on an average weekly basis, cows grazing an L sward and offered the F supplement on occasions had significantly lower milk yields and higher milk fat contents (P<005) than those grazing an H sward and offered the S supplement. There were no significant effects on cow live weight or condition score change. The results suggested that grazing swards with a high density of live tillers increased herbage intakes and on occasions milk yield, relative to low density swards. However, small increases in energy intake from sward and supplement effects were used primarily to ameliorate liveweight loss.     

Supplementary feeding of grazing beef cattle

The effects of cereal and protein supplements on feed intake and liveweight gain were studied. In 1975, steers were continuously stocked on autumn pasture and fed no supplement or 8 g dry matter (DM) per kg liveweight (LW) per d as rolled barley (crude protein (CP) concentration 120 g kg^-1), lucerne cobs (CP concentration 190 g kg^-1) or a mixed concentrate (CP concentration 300 g kg^-1). In 1976, steers were continuously stocked or rotationally grazed in summer and fed no supplement or 7 g DM per kg LW per d as either rolled barley (CP concentration 130 g kg^-1) or a mixture of rolled barley and groundnut meal (CP concentration 210 g kg^-1). Herbage organic matter (OM) intakes in 1975 and 1976 were depressed on average by 22 and 15% respectively with supplementation, but total OM intakes were increased by 9 and 15% respectively. Daily liveweight gain was not significantly increased by supplementation in 1975 when herbage allowance was ample but was significantly increased in 1976 when herbage allowance was limited and herbage digestibility was lower. Protein concentration of the concentrate did not significantly affect daily gain in either year nor was there any difference in gain between rotational grazing and continuous stocking.     

THE FEEDING OF SUPPLEMENTARY CONCENTRATES TO DAIRY COWS GRAZING GOOD PASTURE

In an experiment on the effect of feeding concentrates to spring-calved Ayrshire cows grazing leafy pasture 2 treatments were compared. On the control treatment the sole feed of the cows from M ay to October was grazed herbage. On the supplement treatment the cows grazed the same pasture as the control animals, but in addition were fed concentrates at an average rate oi 21 lb per 10 lb milk. Milk yields on the two treatments were not significantly ditferent, either during the summer feeding period or for the complete lactation. The lengths of the lactations and the fat and S.N.F. contents of the milk were not significantly affected by the treatments. The margin between the value of the milk and the cost of the concentrates was reduced significantly by £13 per cow for the complete lactation as a result of feeding the supplements. It is concluded that at the present price of concentrates and value of milk there are no economic advantages to be gained by feeding supplementary concentrates to spring-calved cows if ample herbage of leafy quality is available.     

Variations in herbage mass and digestibility, and the grazing behaviour and herbage intake of adult cattle and weaned calves

Two experiments are described in which groups of lactating cows, non-lactating cattle and weaned calves grazed a sequence of swards varying in maturity and herbage mass under strip grazing management at a daily herbage allowance of 60 g dry matter per kg live weight. Lactating cows ate 43% and 76% more herbage than non-lactating cattle of similar weight in the two experiments but herbage OM intakes per unit live weight by the calves and lactating cows were similar.
Variations in diet digestibility and herbage intake in the lactating and non-lactating cattle with changes in sward conditions were similar. In the first experiment the calves were experienced grazers; the variation in the digestibility of the herbage selected was less in the calves than the adult cattle, but the variation in herbage intake was greater. The calves in the second experiment were younger, and they were inexperienced grazers; their ability to increase herbage intake in response to changing sward conditions was poorer than that of adult cattle, though variations in diet digestibility were similar in all classes.
The practical implications of these results are discussed briefly.     

Concentrate supplementation of grazing dairy cows

Two experiments are described in which twenty-four spring-calving Dutch Friesian cows were allocated between six grazing treatments (two levels of daily herbage allowance × three levels of daily concentrate intake) in a 2 × 3 factorial design. The swards consisted predominantly of perennial ryegrass. A two-machine sward-cutting technique (with correction for herbage accumulation during grazing) was used for estimating herbage intake by cows which grazed swards for 3 or 4d. Experiment 1 was carried out for 16 weeks of the grazing season of 1981 and experiment 2 for 18 weeks in 1982.
Daily herbage OM allowances in both experiments were 16 and 24 kg per cow above 4 cm cutting height. Daily concentrate OM intake ranged from 0.8 to 5.6 kg per cow. The effect of concentrates on herbage intake differed significantly between allowances. At the low allowance level and at daily concentrate OM intakes of 0.8, 3.2 and 5.6 kg per cow daily herbage OM intake was 10.9, 10.6 and 10.4 kg per cow respectively and the mean substitution rate of herbage by concentrates was only 0.1. At the high allowance level and at daily concentrate OM intakes of 0.8, 3.2 and 5.6 kg per cow daily herbage OM intake was 14.8, 13.6 and 12.4 kg per cow respectively and mean substitution rate was 0.5 kg herbage OM (kg concentrate OM)⁻¹.     

THE EFFECT OF NITROGEN AND STOCKING RATE ON THE OUTPUT OF PASTURE GRAZED BY BEEF CATTLE

An experiment was conducted in two successire years to measure the effect of two levels of fertilizer N, 50 and 300 kg/ha (45 and 270 Ib/ac) on the productivity of pastures grazed by young beef cattle. Two stocking rates were imposed at the lower N level and 4 at the higher level. The responses per kg fertilizer N were approximately 1 kg liveweight gain, 20–24 Meal ME and 8–9 kg DM. Maximal yields of about 1000 kg gain/ha (890 Ib/ac) and 19,000 Meal ME/ha (7700 Mcal ME/acre) were recorded. Animal performance was similar on the low and the high N pastures. There was evidence that the chemical quality of pasture was lower on the low N pasture in the first year, but there was no difference in the second year. The numbers of dung pats per ha and the refusal of herbage due to fouling were reduced by Increasing the stocking rate.     

The effect of a cereal supplement during early lactation on the performance and intake of ewes grazing perennial ryegrass at three stocking rates

A comparison was made of the effect of a cereal supplement during early lactation on the performance and intake of ewes suckling two lambs while rotationally grazing pasture at stocking rates of 20, 17 or 14 ewes per ha. Supplement (S) at the high (H) and medium (M) stocking rates resulted in higher organic matter (OM) intakes (grass + supplement) of 2040 and 2500 g d^-1 respectively, compared with the herbage OM intakes of unsupplemented (U) ewes of 1750 and 2040 g d^-1 respectively. At the low (L) stocking rate the total OM intake of supplemented ewes and the herbage OM intake of unsupplemented ewes was similar at 2250 and 2210 g d^-1 respectively.
Lamb growth rate (g d^-1) to 12 weeks of age was significantly lower on treatment UH (229) compared with those on UM (253) and UL (262). Growth rates on S treatments were similar (SH 248; SM 261; SL 272) and there were no significant differences between S and U within stocking rates. Unsupplemented ewes lost significantly more weight during the period of intake measurement than those receiving supplement. The speed of rotation was faster where supplement was not fed at the medium and high stocking rates and herbage accumulation under UH was less than under SH. Only at the high stocking rate did feeding a supplement give a higher financial output.     

Silage and milk production: a comparison between soya, groundnut and single-cell protein as silage supplements

Grass silage made in May from S24 perennial ryegrass was offered ad libitum to twelve Ayrshire cows in a 12-week feeding experiment. The silage had a DM concentration of 217 g kg ^-1, contained 147 g crude protein per kg DM and had a D-value of 64·6. In addition each cow consumed 1 kg hay per d plus concentrate supplements of dried sugar-beet pulp with (A) soya bean meal, (B)‘Pruteen’, a single-cell protein (C) groundnut cake. The three concentrate supplements each contained 250 g crude protein per kg DM and were offered at the rate of 2·9 kg per 10 kg milk. The daily intakes of silage DM were 8·38, 7·94 and 7·49 kg on treatments A, B and C, respectively, with the extreme values being significantly different. The mean daily yields of milk on treatments A and B were both 16·2 kg per cow, and were significantly higher than the yield of 15·2 kg per cow on treatment C. The fat and lactose contents of the milk on the three treatments were not significantly different, but the CP content on treatment C was significantly lower than that on the other treatments. It is concluded that soya bean meal and‘Pruteen’were superior to groundnut cake as a protein supplement in a silage-based ration.     

Effects on performance and carcass composition of turning beef cattle out to pasture early in the spring

Abstract The effects of turning beef cattle out to pasture earlier in the spring than is conventional in Northern Ireland on performance until slaughter in late summer were examined. Thirty‐eight steers, which were initially 525 kg live weight (LW), were divided into blocks of two according to breed type, previous plane of nutrition and LW and were allocated to two treatments at random within each block. Steers on Treatment 1 were turned out to pasture on 14 March and grazed a permanent perennial ryegrass‐based pasture with a mean sward surface height of 8·4 (s.e. ± 0·36) cm until Treatment 2 steers were turned out on 2 May. Thereafter, all steers grazed as a single group until slaughter at the same estimated carcass fat content, which occurred between June and September. Between the two turnout dates, steers on Treatment 2 were given grass silage ad libitum. For the early and late turnout treatments, respectively, LW gains between the two turnout dates were 1·5 and 0·7 kg d^?1, carcass gains from 14 March until slaughter (mean 143 d) were 0·69 and 0·53 (s.e. ± 0·022) kg d^?1, and carcass weights were 370 and 347 (s.e. ± 2·7) kg. It is concluded that, under the conditions of this experiment, turning beef cattle out to pasture in early spring may offer economic benefits in beef production in situations in which this is practicable.     

Effects on milk production of feeding silage and sugar-beet pulp as separate components, in a mixed ration or as an ensiled blend

Twenty early-lactation British Friesian dairy cows were used in a five-treatment, partially balanced change-over design experiment, consisting of four periods each of 4 weeks' duration. Three treatments consisted of offering ensiled blends of silage and sugar-beet pulp produced by mixing 40 (S40), 80 (S80) and 120 (S120)kg beet pulp t^?1 herbage at ensiling. In two further treatments, an untreated silage was supplemented with 5 kg of beet pulp daily, either mixed with the silage prior to feeding (SM) or offered in two equal feeds each day (ST). Silage was offered ad libitum in all treatments, while in addition all cows received 1 kg d^?1 of a concentrate supplement containing 470 g crude protein kg^?1 fresh weight. Dry-matter intakes and milk fat + protein yields increased with increasing level of beet pulp inclusion in the diet, irrespective of whether it was offered in the form of an ensiled blend or as a supplement to an untreated silage. With the exception of D-value (digestible organic matter in the dry matter), which was significantly higher with treatments SM and ST than with the ensiled blend treatment (S80), no significant differences were identified in total ration digestibility or in the efficiency of nitrogen or energy utilization between methods of beet pulp inclusion in the diet. However, offering beet pulp in the form of an ensiled blend reduced the acetate/propionate ratio in rumen fluid compared with offering best pulp as a supplement to an untreated silage. When account is taken of differences in the efficiency of recovery of edible silage dry matter between ensilage systems and of differences in dry-matter intakes between treatments, total milk fat + protein outputs per 10000 kg herbage dry matter ensiled were 55 (s.e. 50·9) and 78 (s.e. 47·5) kg lower when equal quantities of beet pulp were offered as part of an ensiled blend rather than as a supplement to an untreated silage, as in treatments SM and ST respectively. However, these differences were non-significant. Alternatively, in order to produce an equal milk output from ensiling a given quantity of herbage, 12·5 and 16·2% more beet pulp would have been required if the beet pulp had been mixed with the herbage at ensiling, rather than offered as a supplement, as in treatments SM and ST respectively.     

THE DECOMPOSITION OF CATTLE DUNG AND ITS EFFECT ON PASTURE

A total of 228 separate dung pats voided by lactating dairy cows between May and October on a ryegrass/dover sward were studied for 2 years. The pats were on grazed swards receiving, on average, either 440 or 110 lb N/ac (492 or 123 kg/ha) per year. The mean area of the pats was 0.62 ft² (0.058 m²) with no difference in area between the pats on the two N treatments. On average, the pats on the high- and the low-N treatments crumbled in 63 and 55 days, respectively, and disappeared in 115 and 113 days, respectively. Pats deposited in July disappeared significantly quicker than pats deposited in May. The average area of rejected herbage around the pats was 2.63 and 084 ft² (0.244 and 0.078 m²), respectively, 1–2 months, and 1 year after they were voided; but after 2 years the affected areas were recolonized with ryegrass and clover and were grazed normally. It is concluded that the levels of N fertilizer applied had no differential effects on the breakdown of the dung and on the subsequent recolonization of the affected areas by pasture plants.     

EFFECT OF HIGH FERTILIZER NITROGEN AND STOCKING RATES ON LIVEWEIGHT GAIN PER ANIMAL AND PER HECTARE

The effect of increasing annual fertilizer N application rate from 400 to 800 kg/ha (357 to 714 lb N/ac) and stocking rate from 5.0 to 7.5 animals per forage ha (2.02 to 3.04 animals per forage ac) on herbage availability, digestible OM intake and live weight gain was investigated in a grazing experiment repeated in 3 consecutive years. A 21×1 day rotational paddock grazing system was used in which the grazing area was increased in the ratio of 1:1.5:3 on two predetermined occasions. Increasing the fertilizer N application rate increased herbage availability by 12% but failed to increase live weight gain. Increasing stocking rate decreased herbage availability per ha and per animal, and also live weight gain per animal, but increased live weight gain per forage ha by 17.6%.