Utilise grazing, reduce feed costs and maintain milk yield and quality
Take Home Message: Earlier turnout for 2-3h per day in the Spring will decrease total mixed ration intake and have no effect on milk yield or composition, improving margin over feed by 50p/cow/day
Allowing access to grazing for two hours per day in the spring had no effect on milk yield or milk composition in autumn calving dairy cows, but resulted in a reduction in total mixed ration (TMR) intake of 5kgDM/day.
That was the finding of a study at Harper Adams University College, led by Liam Sinclair, to determine the effect of extending the grazing season in spring and increasing the fibre content of the ration on the intake and performance of autumn calving dairy cows.
“We also found that there was no effect of inclusion of 1kg per cow per day of straw on milk fat content in cows that received access to grazing, possibly due to the relatively high fibre levels in the over-wintered grass,” said Dr Sinclair, presenting his findings to delegates at the British Society of Animal Science’s 2009 annual conference.
Milk production from grass by autumn calving dairy cows can be increased through extending the grazing season in early spring, therefore reducing the reliance on more expensive conserved forage and concentrates. Turning cows out to pasture earlier in the spring has also been associated with an increase in milk and milk protein yield.
In contrast, milk fat content may be decreased, possibly due to the lower fibre content of spring grass. So the inclusion of chopped straw in the ration offers the potential of increasing dietary fibre intake and, therefore, maintaining milk fat levels.
Thirty six Holstein-Friesian dairy cows, which were approximately 180 days into lactation, were randomly allocated to one of three dietary treatments based on parity, stage of lactation and performance in the week prior to allocation.
The control group (C) received a total mixed ration (TMR) containing maize silage, grass silage, caustic treated triticale, soyabean meal, rapeseed meal, dairy compound, sugarbeet pulp, molasses and minerals/ and vitamins. The ration was fed once a day at 1.05 of ad-lib intake through Insenetc roughage intake feeders.
The two grazing groups received both the control TMR ad-libitum and two hours of grazing per day or the control TMR with an additional 1kg/cow/day of chopped straw mixed with the ration, along with two hours of grazing per day.
Both grazing groups were restricted from the TMR from 5.00am until turnout each day, at approximately 8.00am, and were set-stocked on a 1.2ha perennial ryegrass sward that had last been grazed at the end of November 2007.
When not grazing, all animals were housed in the same section of a cubicle house. Grazing commenced on March 5, 2008, and the study lasted for three weeks.
Milk yield was recorded at each milking and samples taken for subsequent analysis during the week prior to the study, mid way through the study and at the end of week three. Body weight and condition score were measured at the beginning and end of the study. Grass samples were taken from three random 25cm x 35cm areas of the paddock at 4cm above ground level during weeks one, two and three of the study for subsequent analysis.
“And we found that the average grass dry matter was 221g/kg, while crude protein and neutral detergent fibre were both high at 211g/kgDM and 530g/kgDM respectively,” said Dr Sinclair.
There was no effect of access to grazing or inclusion of straw on milk yield, composition or component yield and, in contrast, cows that received access to pasture consumed on average 5.05kgDM/day less than those that received the TMR alone. There was no effect of treatment on live weight or body condition score change. Assuming standard costings for grazed grass, forages and concentrates results in a saving of over 50p/cow per day grazed.
Summary (pdf) Presentation (pdf)
To view proceedings of all summaries presented at the Annual Conference 2009 http://www.bsas.org.uk/Publications/Annual_Conference_Proceedings/ To view all Powerpoint presentations http://www.bsas.org.uk/Members_Area/ For further information contact: BSAS on 0131 445 4508 or bsas@sac.ac.uk
