SILAGE AND MILK PRODUCTION. A COMPARISON BETWEEN BARLEY AND DRIED GRASS AS SUPPLEMENTS TO SILAGE OF HIGH DIGESTIBILITY

Grass silage made in late May from S23 perennial ryegrass was offered to 14 Ayrshire cows in a 16–week winter-feeding experiment. The silage had a DM content of 23.2% and contained 16–8% CP and 70.4% digestible organic matter in the DM. The silage was fed ad lib. as the sole feed in the control treatment, and supplemented with either barley or higuality dried grass cubes at the rate of 2, 3 and 4 kg/10 kg milk (2, 3 and 4 Ib/gal) in the other 6 treatments. The daily intake of silage DM was 11.6 kg/cow (25.6 lb) in the control, and significantly less in the supplement treatments. Silage intakes were higher in the dried grass than in the barley treatments. The mean daily yields of milk were 14.5 kg.cow (32.0 lb) in the control, 15.7, 16.6 and 17.0 kg (34.6.36.6 and 37.5 lb) in the barley treatments, and 17.8, 20.2 and 19.8 kg (39.2, 44.5 and 43.6 lb) in the drierass treatments, at the 2, 3 and 4 kg rates of feeding, respectively. The solidoat (SNF) content of the milk was lowest in the control treatment and highest in the drierass treatments. It is concluded that grass silage of high digestibility could be made successfully on a farm scale and that, with such a silage, a supplement of higuality dried grass was superior to a supplement of barley for milk production.     

A comparison between barley and groundnut as supplements for dairy cows at pasture

In two 12-week grazing experiments using twelve and eighteen spring-calved cows in 1976 and 1977 respectively, the effects of feeding either a barley or a groundnut concentrate supplement were investigated. The mean yield of herbage DM on offer was 2330 and 2030 kg ha^-1, with crude protein concentrations of 192 and 193 g per kg DM in 1976 and 1977 respectively. Grazed herbage was the sole feed in the control treatment. In the other two treatments the herbage was supplemented with 3 kg per cow per d of a concentrate containing either 82·2% barley or groundnut with mean crude protein concentrations of 109 and 409 g per kg DM respectively. Similar results were obtained in both experiments with average daily milk yields of 18·3, 19·8 and 19·9 kg per cow on the control, barley and groundnut treatments respectively. The supplements had no significant effects on either milk composition or liveweight change. It is concluded, that with an ample supply of herbage of high crude protein concentration, a supplement of groundnut had no advantages over one of barley.     

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.     

THE EFFECT OF HIGH NITROGEN LEVELS AND STOCKING RATES ON MILK OUTPUT FROM PASTURE

An experiment using 40 lactating dairy cows was conducted for 3 successive years to examine the effects of fertilizer N applied at 400 and 700 kg/ha (358 and 627 lb/ac) at stocking rates of 4.94 and 7.41 cows/ba (2 and 3 cows/ac). The animals were grazed in groups of 10 per treatment, using a fixed rotational grazing system, for 22 weeks in each year. Milk ontput/cow and/ha was significantly affected by stocking rate, the mean milk outputs being 2499 and 2218 kg/cow (5498 and 4880 lb/ cow) and 12313 and 16396 kg/ha (11032 and 14691 lb/ac) at the lower and higher stocking rates, respectively. Milk yield/cow at the lower stocking rate was not affected by N level. At tbe higher stocking rate, increasing the amount of N resulted in a 7.4% increase in milk output/cow and/ha. This response to N declined from 1.7% in the first year of the trial to 2.4% in the third year. The response in milk yield to N appeared to he greatest during the first part of the grazing season. Milk composition, liveweight change, and herbage availahilities and intakes were also recorded.     

FURTHER COMPARISONS BETWEEN A RIGID ROTATIONAL WYE COLLEGE' SYSTEM AND OTHER SYSTEMS OF GRAZING FOR MILK PRODUCTION

In two 20-week grazing experiments, a rigid rotational system of grazing termed the ‘Wye College’ system was compared with a flexible paddock-grazing system in 1972 and with strip grazing and set-stocking in 1973. Eight spring calved Ayrshire cows were used on each treatment at a stocking rate of 5 cows/ha (2 cows/ac). The mean daily milk yields per cow were 17·7 and 17·0 kg(39·0 and 37·5 Ib) on the Wye College and the paddock systems, respectively, in 1972; and 17·9, 17·7 and 16·4 kg (39·4, 38·9 and 36·2 Ib) on the Wye College, strip, and set-stocking systems in 1973. The average annual output of milk varied from 11,500 kg/ha (1030 gal/ac) on the set-stocking system to 12,500 kg ha (1120 gal/ac) on the Wye College system, but none of the differences was significant. The most rapid decline in daily milk yield occurred on the set-stocking system in August and September as the amount of available herbage declined. This system requires further investigation. It is concluded that the Wye College system, with its rigid and pre-determined grazing cycle was as effective as either a one-day paddock or a daily strip-grazing system in producing high yields of milk.     

Pasture‐based dairy farm systems increasing milk production through stocking rate or milk yield per cow: pasture and animal responses

A 2‐year whole‐farm study compared pasture‐based systems increasing milk production per ha by increasing either stocking rate (from 2·5 to 3·8 cows ha^?1) or milk yield per cow (from 6000 to 9000 kg cow^?1 lactation^?1) or both. Four treatments (systems), comprising 30 cows each, were compared under the same management and grazing decision rules. The diet was based on grazed pasture, whereas pellets and conserved fodder were fed when deemed necessary. Milk production per ha increased by 0·49, 0·1 and 0·66 in the systems that increased either stocking rate, milk yield per cow or both respectively. Cows in the ‘high milk yield per cow’ systems had a significantly higher body condition score throughout the lactation, but reproductive performance was similar among all groups. Total pasture utilized (11 t DM ha^?1 year^?1) and pasture nutritive value were similar across all systems. This was associated with the grazing rules applied and the ability of accurately supplementing to meet deficits in available pasture. At the whole‐system level, there was a higher marginal efficiency of supplement use when increasing stocking rate than when increasing milk yield per cow or increasing both (0·18, 0·07 and 0·12 kg milk MJ^?1 of metabolizable energy of supplements respectively).     

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.     

Silage and milk production. A comparision between barley and groundnut cake as supplements to silage of high digestibility

Grass silage of hjgh digestibility made in late May from S23 perennial ryegrass was offered to twelve Ayrshire cows in a 16-week winter-feeding experiment. The silage had a DM content of 27.2% and contained 147% crude protein and 70.3% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with barley, groundnut cake or a mixture of barley and groundnut supplying 4.7, 1.5 and 4.7 kg DM per cow per day respectively. The daily intakes of silage DM were 10.8 kg per cow in the control treatment and 8.6, 11.1 and 9.3 kg per cow in the barley, groundnut and barley plus groundnut treatments, respectively. The daily yields of milk were 14.6 kg per cow in the control, and 16.1, 17.6 and 17.9 kg per cow in the three supplement treatments, respectively. The fat content of the milk was highest in the barley treatment, whereas the SNF and CP contents were highest in the barley plus groundnut treatment. It is concluded that with a high digestibility silage, a supplement of groundnut cake was superior to barley for milk production.     

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.     

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.     

FACTORS LIMITING ANIMAL PRODUCTION FROM GRAZED PASTURE*

Animal production from intensively managed pasture (240 units N/ac or 300 kg N/ha applied annually) should in theory reach 11,000 Ib/ac (12,500 kg/ha) of milk or 1550 lb/ac (1750 kg/ha) of liveweight gain per year. The figure for theoretical milk production is achieved in experiments, although rarely approached in commercial practice; the figure for liveweight gain is never approached, either experimentally or commercially. On commereial farms in Britain, the average stocking rate for grazed lowland pasture in 1971 was about 0·74 cow equivalents/ac (l±82/ha), compared with a theoretical target of 1·9/ac; in 1969 fertilizer N application was about 48 units/ae (60 kg/ha). The main purpose of this paper is to suggest reasons for the differences between practical, experimental and theoretical levels of production. Economic factors may deter farmers from intensifying their grassland management, but the deterrent to high stocking rates may be the fear of running out of grass. In practice, ungrazed herbage is used as a buffer, but other feeds might be used for this purpose. Concentrates, pelleted roughages and even long dried grass and silage are too attractive to grazing beef cattle to be offered to appetite; but silage might be used as a long-term buffer. Fouling of pasture reduces efficiency of harvesting, but attempts to overcome this effect, by conditioning of grazing animals, spreading excreta or by alternation of grazing and cutting, have largely been unsuccessful. High production per unit area cannot be achieved without high production per animal. Legumes have often been found to increase production per animal, and a technique has been developed for growing red-clover and grass in adjoining areas and grazing them together. The clover was grazed satisfactorily by dairy cows (and caused no bloat) but failed to increase milk yield per animal. Recent calorimetric studies of grass have shown that the net energy value of digestible organic matter is variable, and in particular is low for late-season herbage.     

The influence of strain of Holstein-Friesian dairy cow and pasture-based feeding system on grazing behaviour, intake and milk production

A comparative study of grazing behaviour, herbage intake and milk production of three strains of Holstein‐Friesian dairy cow was conducted using three grass‐based feeding systems over two years. The three strains of Holstein‐Friesian cows were: high production North American (HP), high durability North American (HD) and New Zealand (NZ). The three grass‐based feeding systems were: high grass allowance (MP), high concentrate (HC) and high stocking rate (HS). In each year seventy‐two pluriparous cows, divided equally between strains of Holstein‐Friesian and feeding systems were used. Strain of Holstein‐Friesian cow and feeding system had significant effects on grazing behaviour, dry matter (DM) intake and milk production. The NZ strain had the longest grazing time while the HD strain had the shortest. The grazing time of cows in the HC system was shorter than those in both the HS and MP systems. There was a significant strain of Holstein‐Friesian cow by feeding system interaction for DM intake of grass herbage and milk production. The NZ strain had the highest substitution rate with the HP strain having the lowest. Hence, response in milk production to concentrate was much greater with the HP than the NZ strain. Reduction in milk yield as a consequence of a higher stocking rate (MP vs. HS system) was, however, greater for the HP and HD strains compared with the NZ strain. The results suggest that differences in grazing behaviour are important in influencing DM intake and milk production.     

THE EFFECTS OF LEVEL OF NITROGEN FERTILIZER ON BEEF PRODUCTION FROM GRAZED PERENNIAL–RYEGRASS/WHITE–CLOVER PASTURES

The treatments in this summer–grazing experiment were designed as a 2 × 3 factorial, there being two levels of nitrogenous fertilizer (nitro–chalk), supplying 0 and 336kg of N/ha per annum (NO and N3, respectively) and three stocking rates. The fertilizer was applied in 7 dressings at approximately three–weekly intervals. The animals used were Hereford x Friesian steers; these were slaughtered at the end of the grazing season. The stocking rates were calculated on the basis of expected herbage production. The experiment was laid out in 6 randomized blocks which were grazed in rotation. Two blocks were cut for conservation before grazing each year; up to the end of June only 4 blocks were used for grazing.
There was little contamination of the swards with unsown species. With the NO swards the clover contents declined each year, but remained fairly high at over 20% in 1965. Clover contents also declined each year in the N3 swards and by 1965 were only 2 to 4%.
The quantities of herbage cut for conservation were higher from the swards receiving N. The live–weight gains of the cattle (per head) were higher at the lower stocking rates, the effect of stocking rate being more noticeable in the July to Oct. period. Live–weight gains per ha increased at the higher stocking rates. In 1963 and 1965, as stocking rates increased carcass weights per animal decreased and carcass quality, as indicated by the commercial grades, was poorer. In 1964, a dry spell from July to Oct. necessitated the removal of cattle from the experiment and the effects of treatment on carcass weight and quality were not apparent.     

The effect of initial spring grazing date and subsequent stocking rate on the grazing management, grass dry matter intake and milk production of dairy cows in summer

The objective of this study was to investigate the effects of an early (February; F) or delayed (April; A) primary spring grazing date and two stocking rates, high (H) and medium (M), on the grazing management, dry matter (DM) intake of grass herbage and milk production of spring‐calving dairy cows grazing a perennial ryegrass sward in the subsequent summer. Sixty‐four Holstein‐Friesian dairy cows (mean of 58 d in milk) were assigned to one of four grazing treatments (n = 16) which were imposed from 12 April to 3 July 2004. Cows on the early spring‐grazing treatment were grazed at 5·5 cows ha^?1 (treatment FH) and 4·5 cows ha^?1 (treatment FM) while cows on the late‐grazing treatment were grazed at 6·4 cows ha^?1 (treatment AH) and 5·5 cows ha^?1 (treatment AM). The organic matter digestibility and crude protein concentration of the grass herbage were higher on the early‐grazing treatment than on the late‐grazing treatment. The cows on the FM treatment had significantly (P < 0·001) higher milk (24·5 kg), solids‐corrected milk (22·5 kg), fat (P < 0·01, 918 g) and protein (831 g) yields than the other three treatments. Cows on the FM treatment had a higher (P < 0·001) DM intake of grass herbage by 2·3 kg DM per cow per day than cows on the AH treatment, which had a DM intake significantly lower than all other treatments (15·2 kg DM per cow per day). The results of the present study showed that grazing in early spring has a positive effect on herbage quality in subsequent grazing rotations. The study also concluded that early spring‐grazed swards stocked at a medium stocking rate (4·5 cows ha^?1; FM) resulted in the highest DM intake of grass herbage and milk production.     

THE EFFECT OF LEVEL OF PROTEIN IN SILAGE ON THE INTAKE AND PRODUCTION OF DAIRY COWS

Two silages of contrasting protein content were compared in a 16-week winter-feeding experiment with 12 Ayrshire cows. One silage contained 8.2% DCP in its DM and the other 15.9% DCP. The silages were fed ad lib . with a supplement of either barley or barley plus groundnut cake. The DM digestibilities of the low and high protein silages were 74 and 67%, respectively, and the calculated S.E.s 56 and 47. Silage and total DM intakes were highest in the treatments containing low protein silage and in those containing groundnut. The mean daily milk yields for the treatments with and without groundnut were 35.4 and 32.s5 Ib (16.1 and 14.8 kg), respectively, with the high-protein silage, and 38.1 and 35.0 Ib (17.3 and 15.9 kg) with the low-protein silage. The S.N.F. contents of the milk were low and averaged 8.26 and 8.34% on the high- and low-protein silage treatments, respectively, and were not affected significantly by the supplements. It is concluded that the low-protein silage was superior to the high-protein silage as a feed for cows, and that the digestibility of the silage DM was a truer indication of quality than protein content.     

Silage and milk production: a comparison between three rates of high-protein concentrate supplementation of grass silages of two digestibilities

Grass silages made from first-harvest perennial ryegrass in mid-May and early-June and termed high-D and low-D respectively had mean DOMD values of 694 and 633 g kg⁻¹ and were offered ad libitum to twelve Ayrshire cows in a 16-week feeding experiment using a cyclic changeover design. The silages were supplemented with a concentrate containing 363g CP per kg DM at daily rates of 1.5, 3.0 and 4.5 kg per cow. The average daily intakes of silage DM were 12.6 and 11.1 kg per cow on the high- and low-D silage treatments respectively, and were not significantly different on the three concentrate treatments. The mean daily milk yields were 171, 18.6 and 21.0 kg per cow on the low-D silage treatments, and 19.6, 21.2 and 22.8 kg per cow on the high-D silage treatments at the 1.5, 3.0 and 4.5 kg rates of concentrate feeding respectively. Fat and lactose concentrations in the milk were not affected significantly by treatment, whereas the CP and SNF concentrations increased progressively and significantly as the rate of supplementary feeding increased. It is concluded that a high-protein concentrate supplement allows silage to make the maximum contribution in the diet, and gives a high response in terms of milk yield and composition.     

Maize silage with a non-protein nitrogen additive as feed for autumn-calving cows

Maize silages made in October were fed to forty-three autumn-calving cows during a 20-week winter feeding trial. The control silage received no additive whereas a non-protein nitrogen (NPN) additive was applied to the other silage at harvest time. The four experimental feeding treatments were: A, maize silage + 6 kg d^?1 barley; B, maize silage with NPN + 6 kg d^?1 barley; C, maize silage + 5 kg d^?1’barley + 1 kg d^?1 extracted decorticated groundnut cake; D, maize silage with NPN. The mean daily milk yields of cows on the treatments were 14.7, 15.1, 15.3 and 15.0 kg respectively. All cows received maize silage ad libitum. There were no significant differences in milk yield but the milk produced by the cows on treatment D had significantly lower concentrations of milk fat, protein and solids-not-fat when compared to the other three treatments. The cows on treatment D had a negative liveweight change which was significantly different (P < 0.05) from those of the cows on treatments B and C.     

Silage and milk production: a comparison between four rates of groundnut cake supplementation of silage of high digestibility

Grass silage made in late May from S24 perennial ryegrass was offered to twelve Ayrshire cows in a 16-week feeding experiment. The silage had a DM content of 25.3%, a pH of 3.91, and contained 16.8% CP and 68.4% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with a cube offered at rates of 0.8, 1.4 and 2.0 kg per 10 kg milk. The cube contained 82.2% groundnut, plus molasses and minerals, and had 37.9% CP in the DM. The daily intake of silage DM was 11.4 kg per cow on average over the four treatments which did not differ significantly. The mean daily milk yields were 14.8 kg per cow in the control treatment, and 16.5, 18.2 and 18.4 kg in the 0.8, 1.4 and 2.0 kg supplement treatments respectively. The SNF, CP and lactose contents of the milk were Wghest on the 1.4 kg supplement treatment. It is concluded that with a high digestibility silage, there is little evidence to support the feeding of more than 1.4 kg of high-protein cubes per 10 kg milk in the declining phase of lactation.     

A COMPARISON BETWEEN A PADDOCK SYSTEM AND A 'WYE COLLEGE' SYSTEM OF GRAZING FOR MILK PRODUCTION

Two grazing systems, a paddock system and a ‘Wye College’ system, were compared in two 20-week experiments nsing 16 and 20 spring-calved Ayrshire cows in 1970 and 1971, respectively. A sward of S23 perennial ryegrass was used, and an average of 342 kg N/ha (305 lb N/ ac) was applied per annum. The paddock system had 28 separate paddocks; one paddock was grazed each day in rotation and occasionally topped in mid-season. The Wye College system had 4 plots of equal size and the cows were offered 1/7 of one plot each day; no back fence was used and surplus herbage was neither cut nor topped. The stocking rate on hoth systems was 1 cow per 0.20 ha (0.49 ac) in 1970 and per 0.16 ha (0.40 ac) in 1971. The mean daily milk yields per cow on the paddock and the Wye College systems were 16.2 and 15.3 kg (35.7 and 33.7 lb), respectively, in 1970; and 18.1 and 18.4 kg (39.9 and 40.6 lb) in 1971. The average annual output of milk was 13,500 and 13,150 kg/ha (1200 and 1170 gal/ac) on the paddock and Wye College systems, respectively. The fat and solids-not-fat (S.N.F.) contents of the milk were not significantly affected by the grazing system. It is concluded that the Wye College system was as effective as the paddock system in producing a high output of mUk per ha, but at a lower cost and with far fewer management decisions.     

THE EFFECT OF STOCKING RATE ON ANIMAL PRODUCTION FROM CONTINUOUS AND ROTATIONAL GRAZING SYSTEMS

Liveweight and wool production data are presented from a grazing management experiment in which continuous stocking was compared with a four-paddock rotational system at three stocking rates on a sown pasture. Significant differences were recorded in liveweight and wool production between stocking rates. The overall effect of management was non-significant but its interaction with stocking rate and year were both significant. At the intermediate stocking rate (8 wethers/ac, 20 wethers/ha) increases in both liveweight and wool production were recorded for the rotational management system; in this treatment there was also less need for supplementary feeding. Greater wool production was recorded from the continuously grazed treatments at both the high and the low stocking rates but there was little effect on liveweight or the need for supplementary feeding.