scholarly journals The effect of fat supplementation of concentrates on digestion and utilization of energy by productive dairy cows.

1981 ◽  
Vol 29 (2) ◽  
pp. 79-92 ◽  
Author(s):  
Y. van der Honing ◽  
B.J. Wieman ◽  
A. Steg ◽  
B. van Donselaar
Keyword(s):  
Dairy Cows ◽  
Milk Fat ◽  
Crude Protein ◽  
Latin Square ◽  
Soya Bean ◽  
Metabolizable Energy ◽  
Simultaneous Reduction ◽  
Gross Energy ◽  
The One ◽  
Lipid Supplement

Two energy balance experiments each used 6 high-yielding dairy cows. In the first, a 3 X 3 Latin square with one replicate, rations were of 7 kg hay and 11 to 14 kg of concentrates having crude protein 251 g and gross energy 17.9 MJ/kg, given alone or with 5% tallow or 5% soya bean oil. Three weeks of adaptation were followed by 10 to 12 days when excreta were collected and gas exchange estimated. Digestibility and metabolizable energy of concentrates and hay were also assessed using wethers fed to maintenance only. Intakes of DM and digestibility of nutrients other than lipid did not differ among treatments with either sheep or cows. There were no apparent differences in rumen fermentation in the one cannulated cow used, and energy loss in urine was also unaffected. Lipid supplement reduced methane loss. Milk yield and milk energy were increased with tallow, with a simultaneous reduction of milk fat and percentage of protein. Soya bean oil reduced the percentage of milk fat and milk energy produced. The second trial, using similar animals and with similar management had a change-over design in which the concentrate was given alone or with 7% tallow. Results confirmed those of trial 1. The effect of level of feeding on the efficiency of utilization of energy is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Energy and nitrogen balance of lactating dairy cows given mixtures of urea-treated whole-crop wheat and grass silage

1998 ◽  
Vol 67 (2) ◽  
pp. 203-212 ◽  
Author(s):  
J. D. Sutton ◽  
S. B. Cammell ◽  
D. E. Beever ◽  
D. J. Humphries ◽  
R. H. Phipps
Keyword(s):  
Dairy Cows ◽  
Milk Fat ◽  
Latin Square ◽  
Metabolizable Energy ◽  
Partial Substitution ◽  
N Losses ◽  
Grass Silage ◽  
Lactating Dairy Cows ◽  
Acid Detergent Fibre ◽  
Gross Energy

AbstractEnergy and nitrogen balances were carried out with four multi-porous Holstein/Friesian cows offered four diets in a Latin-square experiment to evaluate urea-treated whole-crop wheat as a partial grass silage replacement for lactating dairy cows. Grass silage (GS) was produced from the primary growth of a perennial ryegrass sward. Spring wheat (cv. Axona) was harvested at 603 g dry matter (DM) per kg and preserved with 20 (WCW-20) or 40 (WCW-40)kg urea per t DM. The diets were 6 kg DM of a dairy concentrate daily with one of four forage treatments offered ad libitum. The forage treatments were GS alone, a 2:1 DM ratio of GS with WCW-40 (2:1 40), or a 1:2 DM ratio of GS with WCW-20 (1:2 20) or WCW-40 (1:2 40). Each period lasted 4 weeks with energy and nitrogen balances being carried out in respiration chambers over 6 days in the last week. Replacement of GS by diets containing WCW resulted in significant increases in DM intake (P < 0·01). Changes in milk yield and composition were small and non-significant but yields of milk fat and protein were higher on WCW diets than on GS diets (P< 0·05). With increasing proportions of WCW in the diet there were significant linear falls in apparent digestibility of DM (P < 0·001), organic matter (F < 0·001), neutral-detergent fibre (F < 0·01), acid-detergent fibre (F < 0·01), starch (F < 0·001) and nitrogen (P < 0·01). Gross energy intakes (P < 0·01) and faecal (P < 0·001), methane (P < 0·05) and milk (P < 0·05) energy outputs were higher with the WCW diets than with GS but urine energy and heat losses were unaffected. In consequence there were no significant differences among the diets in digestible or metabolizable energy (ME) intakes. However dietary ME concentrations (MJ ME per kg corrected DM) fell with increasing WCW inclusion from 11·54 on GS to a mean of 9·96 on the 1:2 diets (P < 0·001). It was calculated that the ME concentration of the WCW was only 8·1 MJ/kg corrected DM at maintenance intake, considerably lower than values used conventionally. There were no significant diet effects on the partition of ME or on the partial efficiency of ME utilization for milk production (k1). The increasing inclusion of WCW increased N losses in urine (P < 0·05) and faeces (F < 0·01) with no net effect on N digested or retained though there was a small increase in milk N output (P < 0·01). It is concluded that low digestibility is the major cause of the small milk response to the partial substitution of urea-treated WCW for grass silage with no evidence of a reduction in the efficiency of utilization of ME.

The effect of genetic merit and concentrate proportion in the diet on nutrient utilization by lactating dairy cows

1999 ◽  
Vol 132 (4) ◽  
pp. 483-490 ◽  
Author(s):  
C. P. FERRIS ◽  
F. J. GORDON ◽  
D. C. PATTERSON ◽  
M. G. PORTER ◽  
T. YAN
Keyword(s):  
Dairy Cows ◽  
Energy Intake ◽  
Milk Production ◽  
Milk Fat ◽  
Nutrient Utilization ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Output ◽  
Genetic Merit ◽  
Gross Energy

Sixty Holstein/Friesian dairy cows, 28 of high genetic merit and 32 of medium genetic merit, were used in a continuous design, 2 (cow genotypes)×4 (concentrate proportion in diet) factorial experiment. High and medium merit animals had Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA95 fat plus protein), of 43·3 kg and 1·0 kg respectively. Concentrate proportions in the diet were 0·37, 0·48, 0·59 and 0·70 of total dry matter (DM), with the remainder of the diet being grass silage. During this milk production trial, 24 of these animals, 12 from each genetic merit, representing three animals from each concentrate treatment, were subject to ration digestibility, and nitrogen and energy utilization studies. In addition, the efficiency of energy utilization during the milk production trial was calculated.There were no genotype×concentrate level interactions for any of the variables measured (P>0·05). Neither genetic merit nor concentrate proportion in the diet influenced the digestibility of either the DM or energy components of the ration (P>0·05). When expressed as a proportion of nitrogen intake, medium merit cows exhibited a higher urinary nitrogen output and a lower milk nitrogen output than the high merit cows. Methane energy output, when expressed as a proportion of gross energy intake, was higher for the medium than high merit cows (P<0·05), while urinary energy output tended to decrease with increasing proportion of concentrate in the diet (P<0·05). In the calorimetric studies, neither heat energy production, milk energy output and energy retained, when expressed as a proportion of metabolizable energy intake, nor the efficiency of lactation (kl), were affected by either cow genotype or concentrate proportion in the diet (P>0·05). However when kl was calculated using the production data from the milk production trial the high merit cows were found to have significantly higher kl values than the medium merit cows (0·64 v. 0·59, P<0·05) while k l tended to fall with increasing proportion of concentrate in the ration (P<0·05). However in view of the many assumptions which were used in these latter calculations, a cautious interpretation is required.

Milk production in early lactation dairy cows given grass silagead libitum: Influence of concentrate energy source, crude protein content and level of concentrate allowance

1988 ◽  
Vol 46 (3) ◽  
pp. 317-331 ◽  
Author(s):  
B. K. Sloan ◽  
P. Rowlinson ◽  
D. G. Armstrong
Keyword(s):  
Energy Source ◽  
Dairy Cows ◽  
Milk Yield ◽  
Milk Fat ◽  
Crude Protein ◽  
Metabolizable Energy ◽  
Energy Concentration ◽  
Concentrate Energy ◽  
Neutral Detergent Fibre ◽  
Concentrate Energy Source

ABSTRACTThere is increasing interest in how the raw material make-up of concentrates can influence the milk performance of dairy cows. Thus, over two consecutive winters, 54 dairy cows were used to investigate the effects on dry matter (DM) intake, milk yield and its composition of feeding concentrates of diverse energy source (LNDF — 131 g neutral-detergent fibre per kg DM, 492 g starch plus sugars per kg DM; HNDF — 244 g neutral-detergent fibre per kg DM, 293 g starch plus sugar per kg DM) at two formulated crude protein (CP) levels (157v.187 g/kg DM) and three levels of concentrate allowance (9, 11, 13 kg DM). The concentrates were formulated to be of equivalent metabolizable energy concentration (MJ/kg DM) and were offered with silagead libitumfor a 10-week period (weeks 4 to 13 of lactation).Silage intakes were variable but not significantly influenced by concentrate energy source or formulated CP level, except in the 1st year where animals consuming the high CP concentrate ate more silage. Silage DM intake decreased as concentrate allowance was increased with the substitution rate (kg silage DM per kg concentrate DM) increasing as concentrate allowance was increased.Increasing the concentrate allowance effected the expected increases in milk yield. Concentrate energy source did not influence milk yield but the higher CP levels effected a 2-kg increase in milk yield. Feeding of LNDF concentrates depressed milk fat concentration and its yield, the depression being accentuated with each increase in concentrate allowance. The depression in milk fat concentration was negatively correlated with the forage: concentrate ratio of the diet consumed. Furthermore, dietary NDF proportion was shown to account for greater than half of the variation in milk fat concentration. In contrast to the observations made for milk fat, feeding the LNDF concentrates effected an increase in milk protein concentration but only at the lower CP level of the concentrate.

scholarly journals Effects of Starch Level and a Mixture of Sunflower and Fish Oils on Nutrient Intake and Digestibility, Rumen Fermentation, and Ruminal Methane Emissions in Dairy Cows

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1310
Author(s):  
Babak Darabighane ◽  
Ilma Tapio ◽  
Laura Ventto ◽  
Piia Kairenius ◽  
Tomasz Stefański ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Milk Fat ◽  
Latin Square ◽  
Rumen Fermentation ◽  
Fish Oils ◽  
Ch4 Emissions ◽  
Gross Energy ◽  
Experimental Treatments ◽  
Dietary Treatments ◽  
Dietary Oil

Four multiparous dairy cows were used in a 4 × 4 Latin square to examine how starch level and oil mixture impact dry matter (DM) intake and digestibility, milk yield and composition, rumen fermentation, ruminal methane (CH4) emissions, and microbial diversity. Experimental treatments comprised high (HS) or low (LS) levels of starch containing 0 or 30 g of a mixture of sunflower and fish oils (2:1 w/w) per kg diet DM (LSO and HSO, respectively). Intake of DM did not differ between cows fed LS and HS diets while oil supplementation reduced DM intake. Dietary treatments did not affect milk and energy corrected milk yields. There was a tendency to have a lower milk fat concentration due to HSO compared with other treatments. Both high starch level and oil supplementation increased digestibility of gross energy. Cows receiving HS diets had higher levels of total rumen VFA while acetate was lower than LS without any differences in rumen pH, or ruminal CH4 emissions. Although dietary oil supplementation had no impact on rumen fermentation, decreased CH4 emissions (g/day and g/kg milk) were observed with a concomitant increase in Anoplodinium-Diplodinium sp. and Epidinium sp. but a decrease in Christensenellaceae, Ruminococcus sp., Methanobrevibacter ruminantium and Mbb. gottschalkii clades.

scholarly journals The effect of dietary inclusion of barley, unmolassed sugar beet pulp and molasses on milk production, digestibility and digesta passage in dairy cows given silage based diet

1987 ◽  
Vol 59 (2) ◽  
pp. 101-120
Author(s):  
Pekka Huhtanen
Keyword(s):  
Sugar Beet ◽  
Dairy Cows ◽  
Milk Yield ◽  
Milk Fat ◽  
Latin Square ◽  
Rapeseed Meal ◽  
Metabolizable Energy ◽  
Sugar Beet Pulp ◽  
Passage Rate ◽  
Beet Pulp

Ten dairy cows in early lactation were given five different supplements with grass silage ad libitum according to two 5x5 Latin square designs. The supplements consisted of barley (Ba), unmolassed sugar beet pulp (SBP) and molasses (Mo) on dry matter (DM) basis as follows: (A) Ba 1000g, (B) Ba 667 g and Mo 326 g, (C) Ba 417 g, SBP 410 g and Mo 163 g, (D) SBP 983 g and (E) 656 g SBP and 326 g Mo per kg. The lower fat content of SBP and molasses than of Ba was balanced with rapeseed oil. These supplements were fed at the level of 6 kg DM/d. In addition, 1 kg of rapeseed meal was given as a protein supplement. No differences in silage DM intake between the Ba and SBP supplements were found, but inclusion of a high level of Mo depressed silage and total DM intake. Cows given SBP supplements yielded 1.1kg (P < 0.01) more milk and 32 g (P < 0.05) more protein than those given Ba supplements. Milk fat concentration was lower (P < 0.001) on SBP (46.0 g/kg) than on Ba diets (49.1 g/kg) and thus there was no difference in the yield of fat corrected milk(FCM) and milk fat between the two supplements. Inclusion of 2 kg of DM of More reduced the milk (P < 0.001), FCM, fat and protein yields (P < 0.01) compared to diets without molasses. Supplement C increased (P < 0.05) the milk yield compared to the other diets but the milk composition was not affected. The effect of supplements on the digestibility of the ration was determined using acid insoluble ash as a marker. The apparent digestibility of organic matter averaged 0.743 and was not significantly affected by the diet. Digestibility of neutral detergent fibre was higher (P < 0.001) for SBP diets (0.680) than for Ba diets (0.596). Similar differences were observed in the digestibility of other fibre components. However, the digestibility of the silage was not affected by the treatment. Feeding SBP diets resulted in lower (P < 0.001) digestibility of crude protein than did Ba diets. Metabolizable energy (ME) of SBP diets tended to be used more efficiently for milk synthesis than ME of Ba diets. Inclusion of Mo in Ba or SBP did not reduce the efficiency, although the milk yield was decreased. The passage rate of liquid was determined with CoEDTA and that of particles with Cr-labelled straw. The average mean retention time of liquid ranged from 18.0 to 19.9 h and that of particles from 36.8 to 37.7h. Neither time was affected by the treatment. The passage rate of particles from the rumen ranged from 0.045 to 0.048 and that of liquid from 0.096 to 0.104, irrespective of the diet.

scholarly journals Prediction of metabolizable energy values in poultry offal meal for broiler chickens

2010 ◽  
Vol 39 (10) ◽  
pp. 2237-2245 ◽  
Author(s):  
Edney Pereira da Silva ◽  
Carlos Bôa-Viagem Rabello ◽  
Luiz Fernando Teixeira Albino ◽  
Jorge Victor Ludke ◽  
Michele Bernardino de Lima ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Broiler Chickens ◽  
Crude Protein ◽  
Matter Content ◽  
Metabolizable Energy ◽  
Mineral Matter ◽  
Ether Extract ◽  
High Fat ◽  
Collection Method ◽  
Gross Energy

This research aimed at generating and evaluating prediction equations to estimate metabolizable energy values in poultry offal meal. The used information refers to values of apparent and true metabolizable energy corrected for nitrogen balance (AMEn and TMEn) and for chemical composition of poultry offal meal. The literature review only included published papers on poultry offal meal developed in Brazil, and that had AMEn and TMEn values obtained by the total excreta collection method from growing broiler chickens and the chemical composition in crude protein (CP), ether extract (EE), mineral matter (MM), gross energy (GE), calcium (Ca) and phosphorus (P). The general equation obtained to estimate AMEn values of poultry offal meal was: AMEn = -2315.69 + 31.4439(CP) + 29.7697(MM) + 0.7689(GE) - 49.3611(Ca), R² = 72%. For meals with high fat contents (higher than 15%) and low mineral matter contents (lower than 10%), it is suggest the use of the equation AMEn = + 3245.07 + 46.8428(EE), R² = 76%, and for meals with high mineral matter content (higher than 10%), it is suggest the equations AMEn = 4059.15 - 440.397(P), R² = 82%. To estimate values of TMEn, it is suggested for meals with high mineral matter content the equation: TMEn = 5092.57 - 115.647(MM), R² = 78%, and for those with low contents of this component, the option is the equation: TMEn = 3617.83 - 15.7988(CP) - 18.2323(EE) - 96.3884(MM) + 0.4874(GE), R² = 76%.

scholarly journals Metabolic and Productive Response and Grazing Behavior of Lactating Dairy Cows Supplemented with High Moisture Maize or Cracked Wheat Grazing at Two Herbage Allowances in Spring

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 919
Author(s):  
Verónica M. Merino ◽  
Lorena Leichtle ◽  
Oscar A. Balocchi ◽  
Francisco Lanuza ◽  
Julián Parga ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Fat ◽  
Dry Matter ◽  
Body Condition Score ◽  
Latin Square ◽  
Ruminal Fermentation ◽  
High Moisture ◽  
Plasma Urea ◽  
Grazing Behavior

The aim was to determine the effect of the herbage allowance (HA) and supplement type (ST) on dry matter intake (DMI), milk production and composition, grazing behavior, rumen function, and blood metabolites of grazing dairy cows in the spring season. Experiment I: 64 Holstein Friesian dairy cows were distributed in a factorial design that tested two levels of daily HA (20 and 30 kg of dry matter (DM) per cow) and two ST (high moisture maize (HMM) and cracked wheat (CW)) distributed in two daily rations (3.5 kg DM/cow/day). Experiment II: four mid-lactation rumen cannulated cows, supplemented with either HMM or CW and managed with the two HAs, were distributed in a Latin square design of 4 × 4, for four 14-d periods to assess ruminal fermentation parameters. HA had no effect on milk production (averaging 23.6 kg/day) or milk fat and protein production (823 g/day and 800 g/day, respectively). Cows supplemented with CW had greater protein concentration (+1.2 g/kg). Herbage DMI averaged 14.17 kg DM/cow.day and total DMI averaged 17.67 kg DM/cow.day and did not differ between treatments. Grazing behavior activities (grazing, rumination, and idling times) and body condition score (BCS) were not affected by HA or ST. Milk and plasma urea concentration increased under the high HA (+0.68 mmol/L and +0.90 mmol/L, respectively). Cows supplemented with HMM had lower milk and plasma urea concentrations (0.72 mmol/L and 0.76 mmol/L less, respectively) and tended (p = 0.054) to have higher plasma β-hydroxybutyrate. Ruminal parameters did not differ between treatments.

scholarly journals Identification of Genomic Regions Associated with Concentrations of Milk Fat, Protein, Urea and Efficiency of Crude Protein Utilization in Grazing Dairy Cows

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 456
Author(s):  
Hewa Bahithige Pavithra Chathurangi Ariyarathne ◽  
Martin Correa-Luna ◽  
Hugh Thomas Blair ◽  
Dorian John Garrick ◽  
Nicolas Lopez-Villalobos
Keyword(s):  
Gene Ontology ◽  
New Zealand ◽  
Dairy Cows ◽  
Candidate Genes ◽  
Milk Fat ◽  
Crude Protein ◽  
Single Locus ◽  
Protein Utilization ◽  
Grazing Dairy Cows ◽  
Genomic Regions

The objective of this study was to identify genomic regions associated with milk fat percentage (FP), crude protein percentage (CPP), urea concentration (MU) and efficiency of crude protein utilization (ECPU: ratio between crude protein yield in milk and dietary crude protein intake) using grazing, mixed-breed, dairy cows in New Zealand. Phenotypes from 634 Holstein Friesian, Jersey or crossbred cows were obtained from two herds at Massey University. A subset of 490 of these cows was genotyped using Bovine Illumina 50K SNP-chips. Two genome-wise association approaches were used, a single-locus model fitted to data from 490 cows and a single-step Bayes C model fitted to data from all 634 cows. The single-locus analysis was performed with the Efficient Mixed-Model Association eXpedited model as implemented in the SVS package. Single nucleotide polymorphisms (SNPs) with genome-wide association p-values ≤ 1.11 × 10−6 were considered as putative quantitative trait loci (QTL). The Bayes C analysis was performed with the JWAS package and 1-Mb genomic windows containing SNPs that explained > 0.37% of the genetic variance were considered as putative QTL. Candidate genes within 100 kb from the identified SNPs in single-locus GWAS or the 1-Mb windows were identified using gene ontology, as implemented in the Ensembl Genome Browser. The genes detected in association with FP (MGST1, DGAT1, CEBPD, SLC52A2, GPAT4, and ACOX3) and CPP (DGAT1, CSN1S1, GOSR2, HERC6, and IGF1R) were identified as candidates. Gene ontology revealed six novel candidate genes (GMDS, E2F7, SIAH1, SLC24A4, LGMN, and ASS1) significantly associated with MU whose functions were in protein catabolism, urea cycle, ion transportation and N excretion. One novel candidate gene was identified in association with ECPU (MAP3K1) that is involved in post-transcriptional modification of proteins. The findings should be validated using a larger population of New Zealand grazing dairy cows.

The effect of different proportions of hay and fortified rolled barley in the diet on digestible-energy value and urinary-energy excretion by cattle

1972 ◽  
Vol 79 (1) ◽  
pp. 99-103 ◽  
Author(s):  
A. M. Raven
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Rumen Fluid ◽  
Latin Square ◽  
Progressive Increase ◽  
Linear Increase ◽  
Metabolizable Energy ◽  
Digestible Energy ◽  
Gross Energy ◽  
Concentrate Treatment

SUMMARYA 6 x 6 Latin Square balance experiment was carried out using six Friesian steers, each of which initially weighed about 304 kg. The six treatments studied were an all-hay diet and five other diets containing 20,40,60,80 and 100 % of rolled barley fortified with mineral and vitamin supplements, accompanied by correspondingly reduced proportions of hay. Each diet was fed at an estimated maintenance level of feeding.The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in both digestible and calculated metabolizable energy. The actual increase in digestible energy was from 2·62Mcal/kg dry matter (59·3% of the gross energy) on the all-hay treatment to 3·42 Mcal/kg dry matter (79·5% of the gross energy) on the all-concentrate treatment. Use of the determined digestible energy values for the all-hay and fortified barley diets to calculate the digestible energy of the four mixed diets gave results in reasonably good agreement with the determined values, the maximum difference being 0·12 Mcal/kg dry matter, which represented 3·83 % of the determined value. The losses of energy in the urine expressed as percentages of the gross energy of the diets showed a small but significantly linear decrease (P < 0·01) with increase in proportion of barley in the diet. The molar proportions of steamvolatile acids in samples of rumen fluid taken from two animals on each treatment indicated that increase in the proportion of concentrate was associated with tendencies for increase in acetic acid, decrease in propionic acid and little change in butyric acid. The mean digestibility of the organic matter was 62·6 % on the all-hay treatment and 81·8 % on the all concentrate treatment. The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in digestibility of the organic matter. Although intakes of nitrogen decreased with increase in the proportion of concentrate due to a decrease in the amount of dry matter fed, the weights of nitrogen retained were well maintained and when expressed as percentages of intake showed a significantly linear increase (P < 0·01).

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.

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