Source: Ontario Ministry of Agriculture, Food and Rural Affairs
Dairy cow nutrition involves more than just analyzing data and tweaking your herd’s ration, suggested ruminant nutrition expert Dr. Rick Grant during his keynote address at a recent ruminant nutrition conference in the U.S.
Dr. Grant, president of The William H. Miner Agricultural Research Institute, based in Chazy, NY, discussed recent findings in dairy cow nutrition, particularly on fibre digestibility rates. Some of the latest research provides new tools to fine-tune the ration formulation process. Although nutritionists have access to extensive feed analysis reports and precise mathematical models and software to balance the perfect ration, Dr. Grant emphasized the importance of basic feeding approaches to make your herd’s ration exceed expectations.
To illustrate the importance of feeding management, Dr. Grant quoted a study conducted in 2008. It demonstrated factors other than nutrition can account for more than 50 per cent of milk yield variations between herds when the same ration is fed to different herds with similar genetics. In this particular study, milk yields ranged from 20.5 to 33.6 kilograms per day, even though the same ration was used in the trials.
Non-nutritional factors, such as pushing up feed, social interactions, competition at the feed bunk, feed bunk design, animal density, per cent of feed refusal, frequency of feeding, empty feed bunk time and stall comfort, can significantly impact production levels, even if everything looks perfect on paper.
Cows consume an average of seven meals per day and spend five to six hours per day eating. The amount of time cows spend at the bunk reveals a daytime feeding pattern, influenced by feed delivery timing, feed push-up and milking. The most dramatic peak in feeding activity occurs when cows return from the milking parlour and around the time of fresh feed delivery, the latter of which largely influences feeding behaviour.
Making sure feed is equally distributed along the whole length of the feed bunk can help minimize competition when delivering fresh feed. Despite this practice, cows may still be tempted to sample the feed by changing feeding locations at the feed bunk. This sampling behaviour can be exacerbated by variations in the mixing of the ration.
It is common practice on many farms to feed a total mixed ration (TMR) once daily, usually in the morning. Increasing the frequency of feed delivery from once to twice daily will enable your cows to increase their daily feeding time and distribution of feeding time over the course of the day. Changes in feeding time distribution will result in cows having more equal access to feed. Subordinate cows will not be displaced as frequently if they are fed more often. Regardless of feeding frequency, some cows may still sort the TMR.
You can reduce your cows’ sorting behaviours by increasing feed delivery frequency from once to twice daily. Freshly mixed ration, served twice daily, improves rumen fermentation, eating and rumination time.
Feed push-up and feed refusals
When a TMR is fed, cows will sort and push feed forward so that eventually it is no longer within reach. To alleviate this problem, pushing up feed several times daily will ensure your cows have continuous access to feed.
Pushing feed closer to your cows 30 minutes after the last feed will stimulate feeding and reduce competition at the feed bunk. Feed pushed up may reduce neck injuries caused from cows applying excessive pressure on the feed barrier while trying to reach further into the manger. Pushing up feed is more important during the day than at night. Ideally, you should push up feed every 30 minutes for two hours post feeding.
Try to ensure the manger never remains empty for more than three hours. Ideally, cows should have access to feed 24 hours a day, seven days a week. You should aim for a refusal rate of about three per cent. Feed accessibility stimulates feeding behaviour which, in turn, optimizes dry matter intake and milk production. Constant feed availability reduces cows’ restlessness and promotes lying time in the stalls.
Stocking density and competition
Several studies have demonstrated cows will choose lying over eating. In a freestall housing system, having a sufficient amount of stalls to accommodate the number of cows in a pen is critical. Milk yield per cow is directly correlated with the number of available stalls per cow. The Code of Practice for the Care and Handling of Dairy Cattle states stocking density must be less than 1.2 cows per stall or 120 per cent stocking density. Stocking densities less than 100 per cent have been shown to improve milk production.
As stocking density increases, the frequency of aggressive behaviours and displacement of subordinate cows rises. In such cases, cows will spend more time standing in alleys waiting for a stall to become available. Rest deprivation increases stress levels in the herd. This reduces milk yield, feeding and rumination time, and predisposes cows to lameness and other health issues. Stalls should be available in sufficient numbers and of the proper dimensions and comfortably bedded. The amount of bedding used promotes lying time, which promotes milk production. If the stall covering is visible, it is a clear indication you’re not using enough bedding.
In a group housing system, cows will exhibit their social behaviour as observed on pasture. They will eat, rest and ruminate at the same times when undisturbed. You can also observe social hierarchy among cows. Many factors can interfere and negatively influence dairy cow performance. Situations such as limited bunk space and feed access time, restricted feeding, and inconsistent feeding schedule, can negatively influence cow behaviour and affect subordinate cows. Insufficient bunk space can increase aggressive behaviour and limit the ability of subordinate cows to access feed when needed.
The Code of Practice recommends providing a minimum 24 inches of linear bunk space per cow for mature milking cows. For close-up dry cows and early lactation cows, the linear bunk space should be increased to 30 in. Cows do not generally fill more than 80 per cent of 24-inch headlocks. Your management program should minimize all aspects that may create stress in your herd and promote situations where aggressive behaviours can occur.
Ration balancing is an important aspect of your dairy farm management, but so are other factors, such as bunk space, layout and operational considerations, including bunk management and feed delivery. A complete assessment and adjustment of your feeding system can positively affect your herd’s health and productivity.
This article was originally published in the December 2014 edition of the Milk Producer Magazine.
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Author: Mario Mongeon, Livestock Specialist/OMAFRA