Source: OMAFRA
As dairy herd sizes increase and group housing becomes more predominant, it’s now more important than ever to understand factors that can affect a cow’s behaviour. A complete assessment of your feeding system and adjusting it as needed can have a positive impact your herd’s health and productivity.
Researchers have looked into many aspects of feeding over the past few years. Let’s take a closer look at group housing, total mixed ration [TMR] feeding and cow feeding patterns to see where you could make adjustments to improve overall performance.
Group Housing
Free-stall housing has become the choice of many dairy producers as their herd sizes have increased. In a group housing system, cows exhibit the same social behaviour you see on pasture. They will tend to feed, rest and ruminate at the same times.
You can observe social hierarchy as well. Many factors can negatively influence cow performance: limited bunk space, limited feed access time, restricted feeding, inconsistent feeding schedule, infrequent feed push-up and heat stress. They can particularly affect subordinate cows. For example, studies have shown insufficient bunk space increases aggressive behaviour and is believed to limit the ability of subordinate cows to access feed when they want to.
Look closely at your feeding management program. Minimize factors that can create stress in the herd and promote aggressive behaviour.
TMR Feeding
A TMR is the preferred feeding system for large herds. It offers many advantages in free stalls, and is considered the optimal way to provide your cows with a balanced ration. Uniformly mixed ingredients help maintain a stable and efficient microbial population in their rumens.
Even with perfect mixing, however, cows in certain circumstances will sort through the mix once it’s in the bunk. University as well as on-farm trials have observed extensive TMR sorting in feed bunks.
These trials indicate that cows sorted against coarse particles. This sorting was more evident for TMRs containing greater amounts of alfalfa hay, and there was a large variation in sorting among cows. Factors that may make a TMR prone to sorting include:
high dry matter content and large particle size of forage and mix;
- variation in bulk density of feed ingredients;
- large pieces of cobs and husks in the corn silage;
- the amount and quality of hay added to mix;
- improper sequencing of ingredients into the mixer;
- frequency of feeding and pushing feed back within reach of cows;
- availability of bunk space;
- bunk access time.
Ruminal pH tends to decline following meals, with the rate of pH decline increasing as meal size increases and dietary neutral detergent fibre (NDF) concentration decreases. Bunk management practices that prompt cows to eat fewer and larger meals more quickly [slug feeding] may be associated with an increased incidence of subacute ruminal acidosis and, potentially, laminitis. TMR sorting is a key factor in some cases.
Feeding Patterns
A 2003 British Columbia study examined the normal feeding pattern of lactating cows housed in free stalls and fed a TMR free choice. Cows were provided the industry recommended 0.6 m [two feet] per cow of feed bunk space allowance. Researchers found that cows consumed an average 7.3 meals per day and spent six hours per day eating.
Observations of when cows headed to the bunk clearly showed they prefer eating during daylight hours. The timing of feed delivery, feed push-up and milking also influence this. Further, it’s clear that the most dramatic peaks in feeding activity occur around the time of feed delivery and returning from the milking parlour.
A later study by the same group examined which of the two events-time of feed delivery or return from the milking parlour-stimulates dairy cattle more to go to the feed bunk. In this study, 48 lactating Holstein cows each received two treatments: milking and feed delivery times coinciding, and feed delivery six hours after milking.
When animals were fed six hours after milking, they increased their total daily feeding time by 12.5 per cent. This change was mostly driven by a small decrease in feeding time during the first hour after milking and a large increase in feeding time during the first hour immediately following delivery of fresh feed.
Despite the change in feeding time, feed delivery six hours after milking didn’t change the daily lying time of the cows. This meant the animals minimized the amount of time they spent idly waiting for feed or feed bunk access. These results indicate that the delivery of fresh feed has a greater impact on stimulating cows to get up and feed than does the return from milking.
When you feed a TMR, cows will sort and push the feed forward so that it is eventually out of their reach. To alleviate this problem, pushing up the feed closer to the animals several times a day will ensure they have continuous access to it. Contrary to popular belief, recent studies indicate that pushing up feed has no significant impact on increasing bunk attendance, even if it’s an important management practice to ensure continuous feed access.
Many farms commonly feed a TMR once a day, usually in the morning. A 2005 British Columbia study evaluated the effect of increasing feed delivery frequency. Results indicate that increasing frequency to twice from once per day, and four times from twice per day respectively let cows increase their daily feeding time and distribution of feeding time over the course of the day. The changes in distribution of feeding time resulted in cows having more equal access to feed. Researchers also noted that when subordinate cows were fed more often, they weren’t displaced as frequently.
Regardless of feeding frequency, researchers observed, the TMR’s NDF content increased throughout the day. This indicated that TMR sorting occurred. However, increasing the frequency of feed delivery to twice a day from once per day reduced the amount of sorting. In fact, they found that the leftovers in the bunk contained eight per cent more forage when the cows were fed only once compared to twice per day.
Ration balancing has always been recognized as an important aspect of managing a dairy farm. Other aspects of the feeding system, such as bunk space, layout and operational considerations such as bunk management and feed delivery have been identified as key factors as well.
References: DeVries, T. J., and M. A. G. von Keyserlingk. 2005. Time of feed delivery affects the feeding and lying patterns of dairy cows. J. Dairy Sci. 88:625-631. DeVries, T. J., M. A. G. von Keyserlingk, and K. A. Beauchemin .2003a. Diurnal feeding pattern of lactating dairy cows. J. Dairy Sci. 86:4079-4082. DeVries, T. J., M. A. G. von Keyserlingk, and D. M. Weary. 2004. Effect of feeding space on the inter-cow distance, aggression, and feeding behavior of free-stall housed Holstein dairy cows. J. Dairy Sci. 87:1432-1438.
This article first appeared in the Ruminations column of The Milk Producer Magazine, March, 2006.
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