Topical Research at Harper Adams’ DAIRY
TECHNOLOGY WORKSHOP
The use of activity monitors to improve the health and welfare of dairy cows
80% of cows identifi ed as in heat through the use of collars were confi rmed as such. The biggest problem was the unknown quantity of cows that the system failed to pick up, explained Carole Brizuela MRCVS. Milk sampled twice a week to monitor progesterone levels and predict oestrus across the group revealed a six week cycle pattern, similar to that predicted by the collars. However a signifi cant number of cows were missing from the collar predictions. Collar reporting levels were set to 5x the rate of normal activity, but further research revealed that the missing cows showed activity only 3x the normal rate when in heat. This inaccuracy applied to a large proportion of the herd. Whilst a positive report indicating oestrus was largely accurate, where anoestrous was reported, this was incorrect 68% of the time with 62% of those actually in heat. Half the cows in the group were simply not showing signs of heat.
This had prompted further investigation which highlighted very low levels of progesterone. It is known that high levels are required for active heat but the herd members were demonstrating low levels even halfway through pregnancy leading to the recommendation that herds using Heatime fi rst run a progesterone analysis to help set appropriate minimum activity levels.
What are your cows telling you?
Owen
Armstrong of Lambert, Leonard & May Vets outlined the importance of watching your cows to learn what they are telling you
rather than just what is in front of you on paper. ‘Cow Signals’ is a system designed to interpret how effectively the ‘six freedoms of the pasture’ are provided when cows are housed. The six freedoms are summarised as: Feed, Water, Light, Air, Rest and Space, all of which directly affect the health and therefore productivity of cows. The manner in which feed is presented to cows can have a considerable impact on consumption. Cows ‘sorting’ through the ration is inevitable, however this can be detrimental to younger or quieter individuals who have to wait until the more dominant cows have fi nished when feeding occurs in waves. Allowing enough space for the herd to feed at the same time means that the same mix would be available to all cows. Signals to look out for that may indicate inadequate access or the need for more frequent pushing up include cows standing sideways whilst eating, over reaching and the feed ridge distance from the barrier.
Cows have trouble keeping cool as the rumen acts as a huge fermentation vat. An ideal temperature is 5 to 150C, so good ventilation and air fl ow is essential. Signs to look for when assessing air fl ow includes cows panting; their primary method of controlling body temperature. Increased respiration rate of above the normal rate of 20 to 30 breaths per minute could indicate a problem whilst heat stress is likely to occur over 200C. Timely lighting systems are very important in moderating cow biorhythms. Whilst increased light increases feeding rate, achieving maximum intake with 24 hour light, there is a downside. Excess melatonin is produced in these instances which affects fertility and a period of eight hours darkness has been discovered to aid optimum egg development.
Adequate rest time and individual space has long been acknowledged as an essential factor in optimising production, however it is particularly important from immediately pre-calving to around three weeks post-calving where a straw yard provides the optimum environment. All ligaments relax due to the hormones produced at calving and this includes those supporting the pedal bone in the cow’s foot. Sole damage is common, so extended space encourages fresh calvers to lie down which they are sometimes reluctant to do through discomfort. A good sign to look out for in this instance is a cow dipping her head or extending a front foot (an intentional movement) without then lying down.
For more information on ‘Cow Signals’, you can contact your local DairyCo Extension Offi cer or visit
www.cowsignals.org.uk
Practical rationing to reduce the methane output from dairy cows
One of the hottest topics within popular media was tackled by Harper Adams’ Dr Kenton Hart. He outlined practical steps that can be taken by livestock farmers looking to reduce methane emissions, 95% of which is produced through regurgitation rather than the popular ‘fart’ belief!
Owen Armstrong
54 THE JOURNAL JUNE 2010
Whilst Japan is using chemical solutions and America introducing antibiotic tools, both of which are illegal in the UK, focussing on
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