Whole-crop wheat for dairy cows: effects of crop maturity, a silage inoculant and an enzyme added before feeding on food intake and digestibility and milk production

2002 ◽  
Vol 74 (2) ◽  
pp. 307-318 ◽  
Author(s):  
J. D. Sutton ◽  
R. H. Phipps ◽  
E. R. Deaville ◽  
A. K. Jones ◽  
D. J. Humphries
Keyword(s):  
Food Intake ◽  
Milk Production ◽  
Starch Content ◽  
Latin Square ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Significant Treatment ◽  
Energy Value ◽  
Lactating Cows ◽  
Crop Maturity

AbstractTo measure the effect of stage of maturity of whole-crop (WCW) on its composition, digestibility and feeding value winter wheat was harvested at different maturities in two successive years. In year 1 WCW was harvested at 301(low dry matter (DM)) and 511(high DM) g DM per kg and ensiled and at 584 g DM per kg and treated with 40 kg urea per t DM before being stored (urea-treated WCW). Part of the high DM WCW was treated with an additive containing Lactobacillus buchneri at harvest. In year 2 WCW was harvested at 321 (low DM) and 496 (high DM) g DM per kg and ensiled before both crops were offered to the cows with or without a fibrolytic enzyme sprayed on the forage just before feeding. In both years the WCW was offered ad libitum in a 2: 1 WCW: grass silage DM ratio with 10 kg fresh weight concentrates per day to 40 early-lactation Holstein-Friesian cows in a 13-or 15-week production study with a continuous design and to four fistulated lactating cows in a 4 ✕ 4 Latin-square experiment for measurement of diet digestibility. In both years neutral-detergent fibre (NDF) content decreased and starch content increased with advancing maturity. In the production trials, DM intake increased (P 0·01) with advancing maturity but milk yield was not significantly affected. Milk protein yield was increased by urea-treated WCW. The additives had no effect on food intake or milk production. In year 1, digestibility of all fractions except starch was lower for high DM WCW than low DM WCW but for urea-treated WCW only the digestibility of starch and energy was lower than digestibility of the low DM WCW fractions. The inoculant had no significant effect. In year 2 crop maturity had no significant effect on digestibility but the enzyme reduced the digestibility of neutraland acid-detergent fibre (NDF and ADF, P 0·05). In year 1, each of the forage mixtures was offered to sheep at 12 g DM per kg live weight per day. There were significant treatment effects on the digestibility of DM (P 0·05) and organic matter (OM) (P 0·01) and on DOMD (digestible OM in the DM) (P 0·01) with the highest values being obtained for urea-treated WCW and the lowest for the inoculant-treated high DM WCW. Digestibility coefficients for NDF and ADF were highest for the urea-treated WCW while starch digestibility was essentially complete for all the WCW treatments. The metabolizable energy value (MJ/kg corrected DM) of the WCW decreased with advancing maturity when measured with both the lactating cows (10·4, 9·3 and 9·0) and the sheep (11·4, 10·8 and 10·3) in contrast to the predictions based on the chemical composition (9·6, 10·4 and 12·4). It is concluded that food intake increases with advancing crop maturity but milk production responses are small. Effects on digestibility were inconsistent but the energy value measured in the cows fell with advancing maturity in both years. The increase in crop yield per ha with advancing maturity is likely to be the most important factor influencing the decision to harvest later. The silage additives tested were not beneficial.

A comparison of starchy and fibrous concentrates for milk production, energy utilization and hay intake by Friesian cows

1987 ◽  
Vol 109 (2) ◽  
pp. 375-386 ◽  
Author(s):  
J. D. Sutton ◽  
J. A. Bines ◽  
S. V. Morant ◽  
D. J. Napper ◽  
D. J. Givens
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Yield ◽  
Carbohydrate Source ◽  
Lactating Cows ◽  
Concentrate Inclusion ◽  
Friesian Cows

SummaryTwenty-four Friesian cows were allocated to one of four diets for weeks 3–14 of lactation following 2 weeks on a common diet. The diets (kg air-dry feed/day) were 7–2 kg hay and 10·8 kg either starchy or fibrous concentrates (60S and 60F) or 3·5 kg hay and 14·0 kg either starchy or fibrous concentrates (80S and 80F). Rumen samples were taken by stomach tube in weeks 10 and 12 of lactation and the digestibility of the diets was measured with four cows per treatment during weeks 13 and 14. The digestibility of the same feeds was also measured in sheep at maintenance.The principal carbohydrate constituents of the concentrates were barley, wheat and cassava in the starchy concentrates and citrus pulp, sugar-beet pulp and wheat feed in the fibrous concentrates. The concentrates were designed to have similar concentrations of metabolizable energy (ME) and the diets were planned to provide similar intakes of digestible energy and crude protein.Milk yield and composition were very similar for treatments 60S and 60F. With the higher proportion of starchy concentrates (80S), milk yield was about 20% greater than on 60S, fat concentration fell severely but protein and lactose concentrations were unaffected. With the higher proportion of fibrous concentrates (80F), milk yield and the protein and lactose concentration were similar to values on 60F but fat concentration was lower, though not nearly so low as on 80S. Milk energy yield was reduced by the higher proportion of concentrates but was unaffected by type of carbohydrates. Live-weight changes were small.In both the sheep, consuming at maintenance, and the lactating cows consuming at about 3 times maintenance, digestibility of dry matter, organic matter and energy was higher with the higher concentrate diets but was unaffected by type of concentrate. The digestibility of fibre was greater with the fibrous concentrates but the effect of level of concentrate inclusion was inconsistent. Digestibility coefficients were consistently lower for the lactating cows than for the sheep.The proportion of acetic acid in the rumen volatile fatty acids in the cows was higher and the proportion of propionic acid was lower with the fibrous concentrates. The differences were much greater with the higher proportion of concentrates.During weeks 15–22 of lactation the cows were reallocated to concentrate treatments and given hay ad libitum. Hay intake was about 1 kg/day higher with the fibrous concentrates but the difference was not significant. Hay intake fell by about 0·6 kg/kg concentrate intake for both concentrate types. No significant differences in milk yield or composition were established, probably because of incomplete adaptation even after 8 weeks.It is concluded that at concentrate intakes of about 10 kg/day, the source of carbohydrate in the concentrates has little effect on milk production when the concentrates are of similar ME concentration. However, at higher levels of concentrate inclusion, although the diets may have similar ME concentrations, important differences in the yields of fat, protein and lactose occur due to carbohydrate source and these can be related to differences in rumen fermentation.

The rôles of photoperiod and nutrition in the seasonal increases in growth and insulin-like growth factor-1 secretion in male red deer

2001 ◽  
Vol 73 (2) ◽  
pp. 305-311 ◽  
Author(s):  
J. R. Webster ◽  
I. D. Corson ◽  
R. P. Littlejohn ◽  
S. K. Martin ◽  
J. M. Suttie
Keyword(s):  
Growth Factor ◽  
Food Intake ◽  
Growth Rates ◽  
Energy Demand ◽  
Red Deer ◽  
Young Male ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Plasma Prolactin ◽  
Insulin Like Growth Factor

AbstractYoung male red deer follow a seasonal growth pattern that can be shifted by altering the photoperiod they experience. An increase in photoperiod to 16 h of light per day (16L : 8D) during winter advances the onset of rapid growth and high food intake that normally commences in spring. These changes are associated with increased growth hormone (GH) and insulin-like growth factor-1 (IGF-1) secretion. The GH/IGF-1 axis is acutely sensitive to the level of nutrition and the relative rôles of photoperiod and nutrition in determining the spring IGF-1 rise is unknown. The present experiment set out to examine this by exposing two groups of deer (no. = 8 per group) to a photoperiod shift during their 1st year of life (16L : 8D from 2 June), designed to cause accelerated growth and increased food intake after approximately 7 weeks. However, after 6 weeks the food intake (pellets containing 11 MJ metabolizable energy and 160 g crude protein per kg dry matter (DM)) of one group (LDRES) was clamped, thereby preventing the intake component of the response. The intake of the other group (LDAL) remained ad libitum for a further 12 weeks until 6 October, when the experiment concluded.During the first 6 weeks of 16L : 8D, growth rate (118 (s.e. 15·4) g/day) and food intake (1·37 (s.e. 0·031) kg DM per head per day) did not differ between the groups. Food intake following the clamp in LDRES averaged 1·40 (s.e. 0·015) kg per head per day. The intake of LDAL increased 2 weeks after the clamp and thereafter was higher than LDRES (P < 0·001). Food intake of LDAL averaged 2·13 (s.e. 0·051) kg during the nutritional clamp period. Growth rates increased in both groups during the first 3 weeks of the clamp, averaging 237 (s.e. 25·0) g/day, then growth slowed in LDRES and live weights diverged. Growth rates until the end of the experiment (147 (s.e.23·0) g/ day v. 299 (s.e. 12·5) g/day, P < 0·001) and mean live weight over the last 5 weeks of the experiment were lower (P < 0·05) in LDRES than LDAL, weights reaching 88·3 (s.e. 1·86) kg and 97·9 (s.e. 2·74) kg respectively on the final sampling date. Metatarsal bone length grew more in LDAL than in LDRES (3·1 v. 2·2 cm, s.e.d. = 0·23, P < 0·01). Prior to the nutritional clamp, mean plasma prolactin and IGF-1 concentrations increased at 3 and 6 weeks after 16L : 8D respectively, in both groups. Prolactin concentrations were lower in LDRES than LDAL on two occasions, at weeks 3 and 7 after the onset of the nutritional clamp, and IGF-1 concentrations were lower in LDRES than LDAL (676 v. 872 ng/ml, s.e.d. = 73·8, P < 0·05) over the last 7 weeks of sampling.In summary, a photoperiodically driven increase in IGF-1 occurred even when the usual associated increase in food intake was prevented. This indicates that the seasonal IGF-1 rise in red deer is not a consequence of the increased food intake, although the latter appears necessary to maintain elevated IGF-1 concentrations. The rise in IGF-1 may therefore be considered as a component of the photoperiodically entrained seasonal drive to grow, and the increase in food intake a response to satisfy the increased energy demand.

Supplementary feeding of dairy cows on continuously stocked pasture

1984 ◽  
Vol 103 (1) ◽  
pp. 161-170 ◽  
Author(s):  
P. G. Jennings ◽  
W. Holmes
Keyword(s):  
Dairy Cows ◽  
Latin Square ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Total Output ◽  
Control Group ◽  
Stocking Rate ◽  
High Quality ◽  
Treatment Groups ◽  
Stocking Rates

SummaryTwo experiments were conducted with milking cows on continuously stocked perennial ryegrass pastures. In each a control group, T0, received 1 kg/day of a concentrate supplement and treatment groups T1 and T2 received 4 kg (Expt 1) or 5 kg/day (Expt 2) of a low quality T1 or a high quality T2 concentrate. In Expt 1 treatments were applied continuously for 14 weeks to a total of 30 cows. In Expt 2 a Latin square design for 9 weeks was conducted with 18 cows. The stocking rate of the pasture declined from 9·6 to 5·1 cows per ha (mean 6·7 cows/ha) from May to August (Expt 1) and was maintained at 3 cows/ha in August-October (Expt 2).Supplements increased total intakes by 0·92 and 0·77 kg organic matter (OM)/kg OM supplied in the concentrates respectively for Expts 1 and 2. Milk yields increased by 0·6 and 0·5 kg/kg concentrate supplied and supplemented cows showed small increases in live weight. Differences in lactation milk yield just approached significance. Grazing times were only slightly reduced by supplements and bite sizes were lower than normal. There was no important difference in animal performance between the two concentrates. The total output from the pasture was 19·6t milk and 115 GJ of utilized metabolizable energy per hectare.Reasons for the high supplementary effect of the concentrates and its implications for stocking rates are discussed.

The effect of body reserves at farrowing on the reproductive performance of first-litter sows

1989 ◽  
Vol 48 (2) ◽  
pp. 449-457 ◽  
Author(s):  
B. P. Mullan ◽  
I. H. Williams
Keyword(s):  
Food Intake ◽  
Milk Production ◽  
Reproductive Performance ◽  
Live Weight ◽  
Low Level ◽  
Body Reserves ◽  
H 30 ◽  
Voluntary Food Intake

ABSTRACTThe level of body reserves in first-litter sows was manipulated by giving gilts one of three levels (high (H), medium (M) or low (L)) of food from selection (44 kg live weight) to parturition. The aim of this experiment was either to maintain or to mobilize these reserves during lactation (31·4 days) by feeding sows to appetite (high (H)) or 2·0 kg/day (low (L)).When the level of body reserves was increased prior to farrowing (171 kg live weight, 32 mm backfat) sows had a lower voluntary food intake during lactation than those animals that farrowed with a low level of body reserves (126 kg live weight, 20 mm backfat) (H-H v. L-H, 3·4 v. 4·9 kg/day; P < 0·001). Both groups had a normal return to oestrous activity after weaning (mean interval between weaning and mating of 14 days) but the heavier animals mobilized more of their body reserves (H-H −30·7 kg live weight, -4·3 mm backfat; L-H -3·6 kg live weight +0·9 mm backfat; P < 0·001). When food intake during lactation was restricted to 2·0 kg/day the interval between weaning and mating was increased by 50% regardless of the level of body reserves present at farrowing. For the same animals, there were insufficient body reserves to support milk production at the same level as for those animals given food t o appetite.

Effects of sources of carbohydrate and protein given at low levels with grass silage ad libitum on the performance of lactating dairy cows

1995 ◽  
Vol 1995 ◽  
pp. 163-163
Author(s):  
K. Aston ◽  
R.J. Dewhurst ◽  
W.J. Fisher ◽  
D.W.R. Davies ◽  
A.B. McAllan
Keyword(s):  
Milk Production ◽  
Live Weight ◽  
Rapeseed Meal ◽  
Grass Silage ◽  
Lactating Cows ◽  
Lactating Dairy Cows ◽  
Production Experiment ◽  
Low Levels ◽  
Main Effects ◽  
Degradable Protein

An effective strategy for milk production is to supplement silage with small amounts of high-protein concentrate based on mixed carbohydrate sources and fish and soyabean meals (Aston et al 1992). Recent work at Trawsgoed by Sargeant and McAllan (1993) using growing steers given high-digestibility grass silage supplemented with rapeseed meal (a source of highly rumen degradable protein) produced similar live-weight gains to those obtained with fish meal. Jacobs and McAllan (1992) concluded that microbial protein yield is greater when the more degradable protein source is given, indicating a better balance in the supply of nitrogen and energy nutrients within the rumen. Lactating cows given grass silage diets have a high requirement for Metabolisable Protein (MP). The source of rumen fermentable carbohydrate may be important when MP supply is derived from degradable dietary protein and hence microbial growth. This study therefore examined the effects of varying the sources of carbohydrate and protein in low levels of concentrate given with high-digestibility grass silage. The main effects observed in the milk production experiment are presented here.

Effect of restricted food intake, before and/or after mating, on the reproductive performance of Greyface ewes

1989 ◽  
Vol 48 (1) ◽  
pp. 149-155 ◽  
Author(s):  
S. M. Rhind ◽  
W. A. C. McKelvey ◽  
S. McMillen ◽  
R. G. Gunn ◽  
D. A. Eiston
Keyword(s):  
Food Intake ◽  
Reproductive Performance ◽  
Live Weight ◽  
Experimental Period ◽  
Metabolizable Energy ◽  
Ovulation Rate ◽  
Daily Ration ◽  
The Mean ◽  
Low Levels ◽  
Lambing Rate

ABSTRACTThe effect on the reproductive performance of Greyface (Border Leicester × Scottish Blackface) ewes of a low level food intake and associated loss of live weight from either 14 days before mating, or from the time of mating, until 11 to 26 days after mating, was investigated. Ewes (252) were allocated to one of three treatments with ewes within each treatment divided into two flocks (flock A: 16 ewes per treatment; flock B: 68 ewes per treatment). Ewes of treatment LL were given a ration providing proportionately 0·5 estimated metabolizable energy (ME) requirements for maintenance from 2 weeks before mating. Those of treatment HL were given a daily ration providing 1·5 estimated ME requirements for maintenance until mating and the restricted ration thereafter. Ewes of treatment HH were given the higher ration throughout the experimental period. Flock A ewes were slaughtered at 11 days post mating and flock B ewes at between 18 and 26 days post mating. Treatment differences in the ovulation rates of flock A ewes were not statistically significant but in flock B, ewes of treatment LL had a lower mean ovulation rate (1·81) than those of treatments HL (2·23) and HH (2·09) (P < 0·001). The lower ovulation rate of LL ewes relative to HL ewes in flock B was reflected in a lower mean potential lambing rate per ewe pregnant than in the HL treatment (1·58 v. 1·79; P < 0·01) and per ewe put to the ram (1·37 v. 1·65; P < 0·01). HL ewes had a slightly lower mean potential lambing rate per ewe pregnant (1·79 v. 1·97; P < 01) and per ewe put to the ram (1·65 v. 1·82; P < 0·05) than HH ewes. Ova wastage rates of LL + HL and HH ewes were 0·26 and 014 (P < 001) respectively at 24 days post mating. Values for LL and HL ewes (0·27 and 0·25 respectively) were not significantly different.Estimated mean conceptus lengths were 370, 500 and 1400 μin for LL, HL and HH ewes respectively (P < 0·05).It is concluded that low food intake before mating reduced the mean ovulation rate and low intakes after mating compromised embryo growth rate and induced a higher rate of ova wastage; this increase in the incidence of ova wastage was not significantly exacerbated by the low levels of intake prior to mating.

scholarly journals The utilization of chopped and pelleted lucerne (Medicago sativa) by growing lambs

1979 ◽  
Vol 41 (2) ◽  
pp. 297-310 ◽  
Author(s):  
D. J. Thomson ◽  
S. B. Cammell
Keyword(s):  
Medicago Sativa ◽  
Protein Content ◽  
Live Weight ◽  
Initial Energy ◽  
Metabolizable Energy ◽  
Net Energy ◽  
Regression Equations ◽  
Energy Value ◽  
Physical Processing ◽  
Net Energy Value

1. The efficiency of utilization of the dietary energy and nitrogen contained in a dried lucerne (Medicago sativa cv. Chartainvilliers) given either chopped (CL) or ground (1.96 mm screen) and pelleted (PL), was measured in a comparative slaughter experiment. Growing lambs were given equal amounts of digestible energy in the chopped or pelleted form at each at each of the three planes of nutrition for a period of 100 d.2. The initial energy, fat and protein content of both the carcass and the total body of the test lambs was estimated from regression equations between fasted (18 h) live weight and these components, derived from a group of twenty-three comparable lambs. The final energy, fat and protein content of the test lambs was determined directly by chemical analyses.3. The metabolizable energy (ME) content of the diets was derived at each plane of nutrition from measured faecal and urinary losses and estimated methane losses. The depression in ME content with grinding and pelleting the dried lucerne was small (CL 8.69 MJ/kg dry matter (DM), PL 8.42 MJ/kg DM).4. The efficiency of utilization of the ME of the dried lucerne for growth and fattening was higher (P < 0.01) when given in the ground pelleted form (0.533), than in the chopped form (0.284). The net energy value of the PL (3.5 MJ/kg DM) was higher than that of CL (2.2 MJ/kg DM).5. Thus lambs fed on PL grew faster and had a higher caracass weight gain, carcass protein and fat retention than lambs fed on CL. The composition of the carcass was not altered by the physical processing treatment.6. Digestion studies with these same CL and PL diets had shown that grinding and pelleting depressed digestion in the forestomachs and increased digestion in the small intestine compared with the chopped form. The increased efficiency of utilization of the gross energy and ME and the higher net energy value of PL was attributed primarily to a change in the site of digestion within the alimentary tract. Associated with this change was a higher value for absorbed amino acids : absorbed energy and an increased apparent absorption of methionine for lambs fed on PL. The difference in the energy costs of eating and ruminating the CL and PL was small.

The effects of anAspergillus oryzaeextract containing alpha-amylase activity on ruminal fermentation and milk production in lactating Holstein cows

2005 ◽  
Vol 81 (3) ◽  
pp. 365-374 ◽  
Author(s):  
J. M. Tricarico ◽  
J. D. Johnston ◽  
K. A. Dawson ◽  
K. C. Hanson ◽  
K. R. McLeod ◽  
...  
Keyword(s):  
Milk Production ◽  
Amylase Activity ◽  
Latin Square ◽  
Alpha Amylase ◽  
Holstein Cows ◽  
Ruminal Fermentation ◽  
Nutrient Metabolism ◽  
Lactating Cows

AbstractThe effects of anAspergillus oryzaeextract containing alpha-amylase activity (Amaize™, Alltech Inc., Nicholasville, KY) were examinedin vivoandin vitro. A lactating cow study employed 20 intact and four ruminally fistulated Holstein cows in a replicated 4 × 4 Latin-square design to examine the effects of four concentrations of dietary Amaize™ extract on milk production and composition, ruminal fermentation and serum metabolite concentrations. The treatment diets contained 0, 240, 480 or 720 alpha-amylase dextrinizing units (DU) per kg of total mixed ration (TMR) (dry-matter basis). The supplemental alpha-amylase increased the yields of milk (P= 0·02), fat (P= 0·02) and protein (P= 0·06) quadratically. The maximum milk yield was obtained when 240 DU per kg of TMR were offered. Ruminalin situstarch disappearance was not affected by alpha-amylase supplementation in lactating cows or ruminally cannulated steers. Supplemental alpha-amylase extract reduced the molar proportion of propionate in the rumen of steers (P= 0·08) and lactating cows (P= 0·04), and in rumen-simulating cultures (P= 0·04). The supplement also increased the molar proportions of acetate (P= 0·06) and butyrate (P= 0·05), and the serum beta-hydroxybutyrate (P= 0·01) and non-esterified fatty acid (P= 0·03) concentrations in lactating cows. The improvements in milk production appear to be a consequence of the effects of alpha-amylase on ruminal fermentation and the potential changes in nutrient metabolism that result from them. We conclude that supplemental alpha-amylase may be given to modify ruminal fermentation and improve milk and component yield in lactating Holstein cattle.

Effects of food intake and composition on the concentration of glucose in the blood of lactating cattle

1977 ◽  
Vol 28 (2) ◽  
pp. 333 ◽  
Author(s):  
TJ McClure
Keyword(s):  
Blood Glucose ◽  
Food Intake ◽  
Rice Straw ◽  
Feed Intake ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Metabolizable Energy ◽  
Lactating Cows ◽  
Maize Meal ◽  
Ad Libitum

A group of 16 cows, each suckling one calf, were fed on rations composed of maize meal, cottonseed meal, urea and rice straw in one of four different ratios and at two levels, (a) ad libitum and (b) in restricted amounts. The composition of the feed affected intake. Both the gross intake and the estimated intake of metabolizable energy were closely correlated with liveweight change. The intake of metabolizable energy was correlated with blood glucose in the cows fed ad libitum, but not in the cows fed on restricted amounts of the rations. It was concluded that feed quality significantly affected the blood glucose concentration of the lactating cows, but that within the ranges used in this experiment, feed intake and the intake of metabolizable energy had little effect.

Effects of sources of carbohydrate and protein given at low levels with grass silage ad libitum on the performance of lactating dairy cows

1995 ◽  
Vol 1995 ◽  
pp. 163-163
Author(s):  
K. Aston ◽  
R.J. Dewhurst ◽  
W.J. Fisher ◽  
D.W.R. Davies ◽  
A.B. McAllan
Keyword(s):  
Milk Production ◽  
Live Weight ◽  
Rapeseed Meal ◽  
Grass Silage ◽  
Lactating Cows ◽  
Lactating Dairy Cows ◽  
Production Experiment ◽  
Low Levels ◽  
Main Effects ◽  
Degradable Protein

An effective strategy for milk production is to supplement silage with small amounts of high-protein concentrate based on mixed carbohydrate sources and fish and soyabean meals (Aston et al 1992). Recent work at Trawsgoed by Sargeant and McAllan (1993) using growing steers given high-digestibility grass silage supplemented with rapeseed meal (a source of highly rumen degradable protein) produced similar live-weight gains to those obtained with fish meal. Jacobs and McAllan (1992) concluded that microbial protein yield is greater when the more degradable protein source is given, indicating a better balance in the supply of nitrogen and energy nutrients within the rumen. Lactating cows given grass silage diets have a high requirement for Metabolisable Protein (MP). The source of rumen fermentable carbohydrate may be important when MP supply is derived from degradable dietary protein and hence microbial growth. This study therefore examined the effects of varying the sources of carbohydrate and protein in low levels of concentrate given with high-digestibility grass silage. The main effects observed in the milk production experiment are presented here.

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