Effects of wild-type, AR1 and AR37 endophyte-infected perennial ryegrass on dairy production in Victoria, Australia

2012 ◽  
Vol 52 (12) ◽  
pp. 1117 ◽  
Author(s):  
P. J. Moate ◽  
S. R. O. Williams ◽  
C. Grainger ◽  
M. C. Hannah ◽  
D. Mapleson ◽  
...  
Keyword(s):  
Milk Production ◽  
Perennial Ryegrass ◽  
Milk Fat ◽  
Ergot Alkaloids ◽  
First Year ◽  
Wild Type ◽  
Grazed Pasture ◽  
Cereal Grain ◽  
Eastern Australia ◽  
Feeding Regimes

A 3-year experiment compared the effects of wild-type ryegrass endophyte and two novel endophytes on milk production in dairy cattle. On three 9.9-ha farmlets in West Gippsland, Victoria, pasture swards were established that were dominant in perennial ryegrass (Lolium perenne) infected with either wild-type, AR1 or AR37 endophytes. Each farmlet was stocked with 25 spring-calving Holstein–Friesian cows, which rotationally grazed nine paddocks within their farmlet during three lactations over 3 years. The three endophytes are known to produce different alkaloids, with wild-type producing ergot alkaloids, lolitrems and peramine, AR1 producing peramine and AR37 producing epoxy-janthitrems. These alkaloids were present in fresh pasture as well as hay and silage made from that pasture. Grazed pasture comprised 53% of estimated annual DM intake. The proportion was least from December to March when the daily ration of 2 kg DM/cow.day cereal grain was increased to 6 kg/day and forage supplements were fed consisting of purchased lucerne (Medicago sativa) hay and pasture silage grown on the farmlets. There were no differences in pasture accumulation rates or nutritive characteristics of ryegrass pastures on the three farmlets and no differences in the production of milk, fat or protein by cows grazing pasture infected with the three endophytes. Ryegrass staggers was only observed in four cows consuming the wild-type-infected ryegrass in the first year when the highest concentrations of lolitrem B were recorded in pasture. Soil samples showed lower numbers of root aphids (Aploneura lentisci), mealybugs (Pseudococcidae) and pasture tunnel moths (Philobota spp.) beneath ryegrass infected with the AR37 endophyte compared with the other two endophytes. Numbers of redheaded (Adoryphorus couloni) and blackheaded (Aphodius tasmaniae) cockchafers did not differ between treatments. Under dairy management and supplementary feeding regimes common to south-eastern Australia, the novel endophytes AR1 and AR37 had no effect on the milk production compared with the wild-type endophyte, and did not cause ryegrass staggers.

Effect of grain supplementation and the provision of chemical or physical fibre on marginal milk production responses of cows grazing perennial ryegrass pastures

2001 ◽  
Vol 41 (4) ◽  
pp. 465 ◽  
Author(s):  
W. J. Wales ◽  
Y. J. Williams ◽  
P. T. Doyle
Keyword(s):  
Milk Production ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Milk Fat ◽  
Crude Protein ◽  
Ground Level ◽  
Large Degree ◽  
Herbage Intake ◽  
Cereal Grain

An experiment was undertaken to establish the marginal milk production response from cereal grain supplementation by dairy cows grazing irrigated perennial pastures in spring and whether the addition of a hay supplement would improve that response. Cows were offered perennial ryegrass (Lolium perenne L.)–white clover (Trifolium repensL.) pasture at allowances (measured to ground level) of 20 or 40 kg dry matter (DM)/cow.day. Additional cows offered the low allowance were also offered supplements of pasture hay as a cube or pellet (2.5 kg DM/day), cereal grain as a pellet (5.0 kg DM/day) or cereal grain plus pasture hay (7.5 kg DM/day) as a pellet (1.75:1 DM basis) or cube (1.97:1 DM basis). The 7 treatments were replicated 3 times, and 63 cows were used (3 cows/treatment). The in vitro DM digestibility, crude protein and neutral detergent fibre (NDF) concentration of the barley and perennial pasture hay were 863 and 563 g/kg DM, 131 and 92 g/kg DM, and 182 and 666 g/kg DM, respectively. Cows from all treatments consumed herbage with an in vitro DM digestibility of 833 g/kg DM, crude protein content of 214 g/kg DM and NDF concentration of 457 g/kg DM compared with the pregrazed herbage on offer of 771, 174 and 527 g/kg DM, respectively. The mean pregrazing herbage mass of 4.13 t DM/ha consisted of perennial ryegrass (507 g/kg DM), white clover (188 g/kg DM), weeds (194 g/kg DM) and dead material (111 g/kg DM). Without supplements, cows consumed 11.2 kg DM/day at the low pasture allowance and 15.6 kg DM/day at the high allowance. Herbage intake did not decline to a large degree when barley was included in the diet, where a substitution rate of 0.2 kg reduction in pasture DM/kg DM cereal grain supplement was measured. The NDF concentration of the diet consumed was lowest (P< 0.05) for the grain pellet treatment (370 g NDF/kg DM) and highest (P&lt;0.05) for the fibre pellet (493 g NDF/kg DM) and the fibre cube (507 g NDF/kg DM) treatments. Fat-corrected milk yield increased (P<0.05)) from 20.1 to 24.5 kg/cow.day when cows consumed 4.5 kg DM cereal grain/day with a marginal milk response of 1.0 kg 4% fat-corrected milk/kg DM concentrate supplement. Supplementation with grain or hay had no significant effect (P>0.05) on milk fat, protein or lactose concentrations. The cows offered the high allowance spent more (P<0.05) time grazing than those offered the low allowance, but there were no significant differences in rumination time. Cows spent more time ruminating when consuming the grain &plus; fibre cube compared with the other supplement treatments, which were lower (P<0.05) and similar. Cows offered pasture at the low allowance ruminated the least. The rumen pH was not different between treatments and averaged 5.9. The ratio of acetate plus butyrate: propionate was not different between treatments and averaged 4.3. This study has shown that feeding cereal grain to cows grazing pastures high in perennial ryegrass resulted in acceptable marginal milk responses of 1 kg milk/kg DM of cereal grain in spring because of sufficient NDF in the diet. As there was adequate NDF in the diet, further supplements with pasture hay as cubes or pellets had no effect on marginal milk responses .

Production responses of dairy cows grazing well-managed kikuyu (Pennisetum clandestinum) pastures to energy and protein supplementation

1996 ◽  
Vol 36 (7) ◽  
pp. 763 ◽  
Author(s):  
M Reeves ◽  
WJ Fulkerson ◽  
RC Kellaway
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Milk Protein ◽  
Protein Supplementation ◽  
Control Group ◽  
Plasma Urea ◽  
Pennisetum Clandestinum ◽  
Cereal Grain ◽  
Metabolisable Energy ◽  
Production Response

Three studies were conducted to examine the production response of Friesian cows grazing well-managed lukuyu (Pennisetum clandestinum) pasture to supplementation with a cereal grain concentrate, with and without the inclusion of formaldehyde-treated protein meal. Mean (¦ s.e.) levels of nutrients in the pasture (g/kg DM) on offer were: 205 ¦ 3 crude protein; 683 ¦ 7 in vitro organic matter digestibility; 239 ¦ 2 acid detergent fibre; 615 ¦ 8 neutral detergent fibre and 4.47 ¦ 0.16, 2.51 ¦ 0.06, 31.96 ¦ 0.98, 0.39 ¦ 0.03 and 3.18 ¦ 0.09 of calcium, phosphorus, potassium, sodium and magnesium, respectively. Study 1 was a 3-farmlet study conducted over 45 days (March-April 1993) involving cows 5-6 months into lactation, which compared 3 levels of concentrate feeding at 0 (R0), 3 (R3) or 6 (R6) kg crushed barley/cow.day. Study 2 was an 18-day extension of study 1 with animals in the seventh month of lactation. The concentrate fed was 72% barley and 24% formaldehyde-treated sunflower meal. Pasture intake of individual cows was determined using an alkane technique. Mean milk yields (L/cow. day) in study 1 were 14.2, 18.3 and 18.0, and in study 2 were 12.5, 18.5 and 17.4 for treatments R0, R3 and R6, respectively. Milk fat (3.77 v. 3.26%), but not milk protein, content of the Ro cows was significantly higher than R6 cows in study 1 only. In study 2, the apparent whole-diet digestibility remained constant as concentrate level rose, indicating a negative effect of concentrate fed on forage digestibility in the absence of buffers. Study 3 was a 3 x 4 factorial design plus a 'control' group (0.5 kg barley/cow.day used as a carrier for minerals) to examine the milk production response to 3 levels of concentrate feeding (3, 6 and 9 kg/cow.day) with 4 levels of formaldehyde-treated canola meal (FTCM; 0, 20, 40 and 60% of concentrate). Rations were iso-energetic within levels of concentrates fed. The control group had significantly lower milk production (17.2 L/cow.day), as well as milk protein (2.90%), plasma urea (PU) (5.90 mmol/L) and P-hydroxybutyrate (G-OHB) (0.525 mmo1L) than other treatment groups. The mean milk production response of 0.6 L milk/kg concentrate fed in study 3 at the 3 kg/day level of feeding was lower than observed in studies 1 and 2 (1.4 and 2.0 L/kg concentrate, respectively). The level of metabolisable energy in the concentrate in study 3 had a significant influence on milk production, milk fat and milk protein levels. Plasma glucose and G-OHB levels significantly increased with the incorporation of FTCM into the concentrate. Nonesterified fatty acid levels dropped significantly below levels of other treatments at the lowest level of inclusion of FTCM. PU levels generally increased in response to increasing metabolisable energy and inclusion of FTCM in the concentrate, with an interaction between them. Milk urea (MU) levels (mmol/L) showed a significant linear (P<0.001; r2 = 0.44) relationship to PU levels (mmol/L) as follows: MU = 0.167 + 0.272PU.

Effects on milk production of feeding wheat supplements to grazing dairy cows in early lactation

1987 ◽  
Vol 27 (1) ◽  
pp. 41
Author(s):  
RC Dobos ◽  
WJ Fulkerson ◽  
PJ Michell
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Early Lactation ◽  
Grazed Pasture ◽  
Herbage Intake ◽  
Significant Difference ◽  
Increase Milk Production ◽  
Grazing Dairy Cows ◽  
Daily Milk Yield ◽  
North Western

Two herds, each of 19 Friesian cows, were run on separate farmlets in north-western Tasmania. One herd (NW) grazed pasture only, and was estimated to be receiving 75% of potential intake, while the second herd (W) received 3.0 kg coarsely hammermilled wheat per cow, daily for 42 days during early lactation in addition to pasture. Although the feeding of wheat increased total feed intake, there was no significant difference between the groups in either daily milk yield (21.5 v. 21.8 L cow-1), milk fat yield (1.1 v. 1.09 kg cow-1), liveweight change (0.05 v. -0.2 kg cow-l) and herbage intake (12.0 v. 12.0 kg DM cow-1 day-1) of cows or of pre- (1.77 v. 1.8 t DM ha-1) and post- (1.31 v. 1.32 t DM ha-1) grazing mass, on farmlets NW and W respectively. We conclude that the feeding of wheat did not increase milk production or improve liveweight change under the conditions of this experiment.

scholarly journals Infant intake of fatty acids from human milk over the first year of lactation

2003 ◽  
Vol 90 (5) ◽  
pp. 979-986 ◽  
Author(s):  
Leon R. Mitoulas ◽  
Lyle C. Gurrin ◽  
Dorota A. Doherty ◽  
Jillian L. Sherriff ◽  
Peter E. Hartmann
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Human Milk ◽  
Acid Composition ◽  
Milk Production ◽  
Milk Fat ◽  
Fat Content ◽  
First Year ◽  
Milk Fatty Acids

Despite the importance of human milk fatty acids for infant growth and development, there are few reports describing infant intakes of individual fatty acids. We have measured volume, fat content and fatty acid composition of milk from each breast at each feed over a 24h period to determine the mean daily amounts of each fatty acid delivered to the infant from breast milk at 1, 2, 4, 6, 9 and 12 months of lactation in five women. Daily (24h) milk production was 336·60 (sem 26·21) and 414·49 (sem 28·39) ml and milk fat content was 36·06 (sem 1·37) and 34·97 (sem 1·50) g/l for left and right breasts respectively over the course of the first year of lactation. Fatty acid composition varied over the course of the day (mean CV 14·3 (sd 7·7) %), but did not follow a circadian rhythm. The proportions (g/100g total fatty acids) of fatty acids differed significantly between mothers (P<0·05) and over the first year of lactation (P<0·05). However, amounts (g) of most fatty acids delivered to the infant over 24h did not differ during the first year of lactation and only the amounts of 18:3n-3, 22:5n-3 and 22:6n-3 delivered differed between mothers (P<0·05). Mean amounts of 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 delivered to the infant per 24h over the first year of lactation were 2·380 (sd 0·980), 0·194 (sd 0·074), 0·093 (sd 0·031) and 0·049 (sd 0·021) g respectively. These results suggest that variation in proportions of fatty acids may not translate to variation in the amount delivered and that milk production and fat content need to be considered.

Protein supplementation of cows grazing limited amounts of paspalum (Paspalum dilatatum Poir.)-dominant irrigated pasture in mid-lactation

2000 ◽  
Vol 40 (7) ◽  
pp. 923 ◽  
Author(s):  
W. J. Wales ◽  
D. W. Dellow ◽  
P. T. Doyle
Keyword(s):  
Milk Production ◽  
Cottonseed Meal ◽  
Milk Fat ◽  
Rumen Fluid ◽  
Protein Supplementation ◽  
Canola Meal ◽  
Paspalum Dilatatum ◽  
Protein Supplements ◽  
Cereal Grain

Two experiments were undertaken in summer to investigate production responses by dairy cows offered paspalum (Paspalum dilatatum Poir.)-dominant irrigated pasture to the inclusion of protein supplements with different rumen degradable protein characteristics in cereal grain-based concentrates. In experiment 1, cows in mid lactation were offered limited amounts of herbage, at an allowance of 28 kg DM/cow. day together with 8.0 kg DM/cow. day of a pelleted supplement containing: (i) mainly barley and wheat; (ii) barley, wheat and canola meal; or (iii) barley, wheat and cottonseed meal for 35 days. The 3 supplements were formulated to have similar in vitro DM digestibilities. In experiment 2 aspects of rumen function were measured in 9 rumen fistulated lactating cows, individually fed indoors on paspalum-dominant herbage harvested daily with a finger bar mower. Cows were offered the same amount of supplements for 28 days. Pasture intakes were similar to those of the grazing cows in experiment 1. In experiment 1, there were no effects (P>0.05) of dietary treatment on herbage intake (10.2 kg DM/cow. day) or selection of nutrients from herbage. The concentration of crude protein in the total diet consumed was lower (P<0.05) for the barley + wheat treatment (137 g/kg DM), compared with the barley + wheat + canola meal and barley + wheat + cottonseed meal treatments, which were 179 and 183 g/kg DM, respectively. In vitro DM digestibility of the feed consumed by cows was similar across the treatments, and all diets contained greater than 400 g neutral detergent fibre/kg DM, indicating there were no limitations due to dietary fibre. There were no significant effects (P>0.05) of dietary treatments on milk production (21.8 kg/cow. day), milk fat concentration (34.1 g/kg) or milk protein concentration (29.8 g/kg). Urea-N was higher (P<0.01) in the milk of cows fed the barley + wheat + canola meal and the barley + wheat + cottonseed meal treatments compared with the barley + wheat treatment. In experiment 2, rumen fluid pH was higher in cows consuming barley + wheat pellets than in cows consuming barley + wheat + canola meal on most sampling occasions. Rumen ammonia-N concentration was lowest in the barley + wheat treatment and highest in the barley + wheat + canola meal treatment. When cows grazing paspalum-dominant irrigated pasture were supplemented with 8 kg DM of a cereal-based supplement, metabolisable protein was calculated to be present in sufficient quantities to support at least 22 kg milk/cow. day and, hence, was not limiting milk production. It is concluded that protein supplements offered to cows in mid-lactation, grazing irrigated pastures in summer, are unlikely to give a milk production response beyond that achieved with cereal grain.

Effect of level of grain supplementation on milk production responses of dairy cows in mid - late lactation when grazing irrigated pastures high in paspalum (Paspalum dilatatum Poir.)

2001 ◽  
Vol 41 (1) ◽  
pp. 1 ◽  
Author(s):  
G. P. Walker ◽  
C. R. Stockdale ◽  
W. J. Wales ◽  
P. T. Doyle ◽  
D. W. Dellow
Keyword(s):  
Treatment Group ◽  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Rumen Fermentation ◽  
Paspalum Dilatatum ◽  
Cereal Grain ◽  
Diminishing Returns ◽  
Supplement Intake

Two grazing experiments tested the hypothesis that a cereal grain-based supplement, fed to cows that are in mid–late lactation and grazing low metabolisable energy and high neutral detergent fibre content paspalum (Paspalum dilatatum Poir.)-type pastures, will increase milk yield, but that this response will diminish with successive increments of supplement. A further objective of this research was to investigate some of the factors, such as altered rumen fermentation pattern, that might vary the point at which diminishing returns start to occur. Cows grazed irrigated perennial pasture at an allowance of either 25 (experiment 1) or 31 (experiment 3) kg of dry matter (DM) per cow per day in late summer–early autumn (mid–late lactation) and were supplemented with cereal grain-based concentrates up to 11 and 7 kg DM/cow.day in experiments 1 and 3, respectively. In experiment 1, there were 3 replicates of 6 treatments (3 cows in each treatment group) that involved the feeding of either 0, 3, 5, 7, 9 or 11 kg DM/cow.day of supplement for 50 days. Experiment 3 was conducted over 35 days. There were 2 replicates of 4 treatments (4 cows per treatment group) that involved the feeding of either 0, 3, 5 or 7 kg DM/cow.day of supplement. A further experiment (experiment 2), associated with experiment 1, examined the effects of offering cereal grain-based concentrates up to 7 kg DM/cow.day to dairy cows consuming 10 kg DM/day of herbage with a high paspalum content on aspects of rumen fermentation. Incremental responses of 40 g/kg fat-corrected milk (FCM) to increasing concentrate intake diminished with increasing concentrate intake, with the level of supplementation at which diminishing returns occurred dependent on herbage allowance and, therefore, herbage intake. At a supplement intake of 3 kg DM/cow.day, the response in FCM was 1.1 kg/kg concentrate DM in both grazing experiments. There were no further increases in milk production with additional increments of concentrates in experiment 3 where the pasture allowance was highest. In experiment 1, where concentrates were offered to a level of 11 kg DM/cow.day, and the pasture allowance was lower, diminishing returns were not as pronounced as in experiment 3 until the highest levels of concentrate intake. Substitution of supplement for herbage was a major factor in causing the diminishing returns in both experiments, but especially in experiment 3, where pasture intakes were higher. Milk fat content was significantly (P<0.05) reduced (41.8 v. 32.5 g/kg) when concentrate intake increased from 9 to 10.4 kg supplement DM/cow.day in experiment 1. It was hypothesised that this reduction in milk fat content was probably due to the effects of subclinical rumen lactic acidosis. This hypothesis was supported by the trend to lower rumen pH for longer periods as supplement intake increased as well as a more variable milk yield at the highest level of supplement intake. We conclude that responses of FCM of 1.1 kg/kg DM cereal grain-based concentrates can be achieved when they are fed twice daily up to 3 kg DM/day to dairy cows grazing restricted amounts of paspalum-type pasture in autumn. Beyond 3 kg DM/day, marginal responses diminished with increasing concentrate intake, with the level of supplementation at which diminishing returns occurred being dependent on herbage allowance and, therefore, intake.

Comparison of two management systems of dairy farmlets based on conservation of either hay or silage

1991 ◽  
Vol 31 (2) ◽  
pp. 195 ◽  
Author(s):  
GW Thomas ◽  
GL Mathews
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Dairy Farms ◽  
Supplementary Feeding ◽  
Management Systems ◽  
First Year ◽  
Storage Losses ◽  
High Storage

Two management systems for dairy farms, early (silage farmlet) and late (hay farmlet) conservation, were compared for milk production in 4 consecutive years, at 2 cowsha. Half of the total silage farmlet area was made to wilted silage in each year. The remaining area was conserved as direct-cut silage in the first year and hay in the fourth year. About 40-50% of the hay farmlet area was made to hay. Over the 4 years, the silage farmlet produced an average of 8.2% more milk and 11.9% more (P<0.01) milk fat per year than the hay farmlet. The improvement in milk and milk fat production averaged 2.7 and 5% (P<0.01) in the spring and 27.4 and 30% (P<0.01) in the period from commencement of supplementary feeding in the summer. On average, the silage farmlet conserved a greater area, but because of high storage losses and greater consumption, it required more brought-in feed than the hay farmlet.

Evaluating the economics of concentrate feeding decisions in grazing dairy cows

2018 ◽  
Vol 58 (7) ◽  
pp. 1329 ◽  
Author(s):  
C. K. M. Ho ◽  
J. W. Heard ◽  
W. J. Wales ◽  
J. L. Jacobs ◽  
P. T. Doyle ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Fat ◽  
Marginal Cost ◽  
Variable Cost ◽  
Significant Variable ◽  
Marginal Revenue ◽  
Short Term ◽  
Cereal Grain ◽  
Farm Profit

Purchased concentrates are a significant variable cost of a dairy business. Farm economic theory states that feeding supplements will enable a dairy farmer to improve profit as long as the marginal revenue received from the milk produced exceeds the marginal cost of the supplement. To do this, the quantities of milk, milk protein and milk fat produced from a unit of concentrate added to the diet are needed. Recent research has compiled results from short-term concentrate feeding experiments conducted in Victoria over a 30-year period. Using these data, relationships for the response of milk production to cereal grain supplements in dairy cows grazing temperate pastures have been developed and shown to be a better predictor than previous relationships. These response functions were used in the present study to investigate the economics of tactical (short-term; weekly, monthly or seasonally) and strategic (medium- to longer-term) supplementary feeding decisions in a pasture-based system, including, specifically, how much concentrate should be fed in a particular farm situation, given a certain feed cost and milk price. In the present paper, the relevant production economics method is explained and applied to determine the amount of supplement to feed that will maximise the margin of total extra milk income minus the total cost of supplement, thereby adding the most to farm profit. Currently, when dairy farmers make decisions about how much more supplement to feed their herd, they are making implicit judgements about the extra milk, and other potential benefits, that they expect to result as well as what the milk will be worth. More finely tuned decisions about feeding supplements based on comparing marginal cost and marginal revenue would add more to farm profit than decisions based on other common criteria, such as feeding supplement for maximum milk production. While some farmers may already be feeding supplements close to the point where marginal cost equals marginal revenue, the formal method of marginal analysis reported here makes explicit what is done implicitly at present and tests farmers’ intuitive decision-making. More detailed information about the responses to supplements and the costs and benefits of feeding supplements under particular circumstances at different times through the lactation has the potential to enable better, more profitable decisions to be made about feeding cows and managing the whole farm.

Effects of the composition of irrigated perennial pasture on the milk production of dairy cows and their responses to supplementation with cereal grain-based concentrates

2008 ◽  
Vol 48 (7) ◽  
pp. 866
Author(s):  
C. R. Stockdale
Keyword(s):  
Milk Production ◽  
High Energy ◽  
Grazed Pastures ◽  
Grazed Pasture ◽  
Cereal Grain ◽  
Species Groups ◽  
Metabolisable Energy ◽  
Trifolium Repens L ◽  
The Difference ◽  
Friesian Cows

The objective of the research described here was to compare the milk production from paspalum (Paspalum dilatatum Poir.)-dominant swards with milk production from perennial ryegrass (Lolium perenne L.)–white clover (Trifolium repens L.)-dominant swards. Eight experiments were conducted over a 2-year period, during which half the cows grazed pastures that had been established for more than 15 years (old pasture) and were dominated by paspalum in summer, while the remaining cows grazed pastures sown within the previous 2–3 years (new pasture), which were dominated by temperate species. Groups of four to five lactating Friesian cows grazed either old or new pasture and were either unsupplemented or were offered ~5 kg DM/cow.day of a high energy supplement (75% barley and 25% wheat). The hypothesis was that milk production would be greater from cows grazing new pastures than old pastures (at common pasture allowances), but that marginal milk responses when cereal grain-based supplements were fed would be greater when cows grazed old pastures; this was only partially supported. Milk yields were generally greater when cows grazed new pastures, but in six out of eight experiments, the advantage was only ~1 kg milk (100 g fat plus protein)/cow or less. In these six experiments, the difference in metabolisable energy density between the pastures was 0.7 MJ/kg DM or less. When concentrates were fed to supplement grazed pasture, there were seasonal variations, but similar marginal responses in milk production were recorded on both pastures throughout the study.

Use of partial mixed rations in pasture-based dairying in temperate regions of Australia

2013 ◽  
Vol 53 (11) ◽  
pp. 1167 ◽  
Author(s):  
W. J. Wales ◽  
L. C. Marett ◽  
J. S. Greenwood ◽  
M. M. Wright ◽  
J. B. Thornhill ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Current Knowledge ◽  
Farming Systems ◽  
Ground Level ◽  
Canola Meal ◽  
Consistent Finding ◽  
Grazed Pasture ◽  
Negative Impacts ◽  
Feeding Systems

There is a growing diversity and complexity of dairy farming systems in Australia. Feeding systems based on the provision of mixed rations to dairy cows grazing perennial pastures (termed partial mixed rations or PMR systems) have emerged and present the dairy industry with opportunities for improved production and feed efficiency, but also with significant challenges. Early research results are beginning to define the situations in which PMR systems are profitable and the mechanisms responsible for the improved milk responses. This review focuses on the role of PMR feeding systems in temperate dairying regions of Australia, highlights initial research findings, and identifies some of the gaps in current knowledge that warrant further research. The key findings were that, when very low allowances of pasture are offered to cows, milk production responses were driven mostly by increases in dry matter (DM) intake, and there appeared to be a minimal contribution to increased energy supply from improved whole tract DM digestibility. Differences in milk responses became apparent when >10 kg of total supplement DM was consumed (0.75 : 0.25 concentrate to forage) as PMR. There was a consistent maintenance of milk fat concentration when increasing amounts of concentrates were consumed as PMR, in contrast with supplements consumed in the dairy. There was also a consistent finding that replacing some wheat in the PMR with canola meal resulted in cows consuming more grazed pasture despite the limitations of very low pasture allowances (10–15 kg DM/cow.day, expressed to ground level). This was accompanied by further increases in energy-corrected milk yield. The potential to improve DM intake was further highlighted when pasture allowance was increased, with intake increasing from 3.6% to 4.5% of liveweight (from 20 to 25 kg DM/day for a 550-kg cow). There was also an indication that ~50% of the milk production benefit from PMR can be captured by providing the concentrate supplement as a grain mix in the dairy. There did not appear to be negative impacts of PMR systems on the social and grazing behaviour or health of cows.

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