Self Locking Head Gates and Crowding
Change Eating Behaviour

For several years, farmers and their advisors have speculated about the effect of self locking headgates on feed intake and eating behaviour. In barns with headgates along part of the manger only, cows often eat the feed behind the headgates last.

A small research study reported at the Dairy Housing and Equipment Systems Conference in Pennsylvania, last month verifies what many people suspected. The trial, conducted by Terry Batchelder at Cornell University, involved two groups of 20 cows in 20 freestalls per group in a 4-row barn. Manger space was 2.3 feet per cow in the pen with headlocks and 2.4 feet per cow in the pen with a post and rail manger, and was adequate for all cows to eat at once if they chose to. Cows were milked 3 times daily, fed twice to the point of excess, and feed was pushed up 3 to 5 times between each milking.

Each "treatment period" of "headlocks" or "no headlocks" lasted 3.5 weeks. Feed intake was measured only during the last two weeks to provide a week for cows to adjust to the manger design. When cows ate through headlocks, feed intake averaged 22.8 Kg of TMR dry matter per cow per day. When the manger design did not include a self-locking headgate, feed intake was 24.0 Kg per cow per day. This difference of 1.2 Kg was "statistically significant (P< .05). In other words, there is a 95% chance that the observed reduction in intake is truly the result of using the self-locking headgates.

The trial was repeated with two groups of 26 cows housed in 20 freestalls per group, to determine the effect of crowding on feed intake. Crowding reduced manger space per cow to 1.75 feet with headgates and 1.84 without, and also decreased access to freestalls and total pen area per cow by 30%.

Feed intakes were 23.8 Kg without headgates and 23.0 with self-locks. Although crowding appeared to reduce feed intake by 0.2 Kg this was "not statistically significant". While it is still logical to expect that crowding 26 cows in an area with 20 stalls is stressful and quite likely could result in lower feed intake, in this trial the small difference measured could have just as easily occurred as the result of normal variation.

The bottom line of this study is that self-locking headgates were associated with a decrease in feed intake of 1.2 Kg of dry matter. The author states that "due to the short time length of the treatments and the switch back design, milk production and body condition scores did not vary between treatments. Yet, one could infer that if these preliminary results are consistent, then increases in dry matter intake should have a positive impact on milk support or body condition".

Based on normal feed conversion a 1.2 Kg drop in daily feed intake can lead to 2 to 3 Kg less milk per day. In higher producing cows, greater weight loss due to lower feed intake could also have a negative affect on fertility and health.

The trial offers little to explain why cows eat less feed through self-locking head gates. One possible explanation for some of the difference in feed "consumed" is that the more restrictive headlocks decrease the amount of feed wasted, when it falls off the cows muzzle and into the manure behind the manger.

A longer trial might assess the likelihood of this being a factor, since feed wastage differences would not lead to differences in production, while feed intake differences would.

Assuming feed costs of roughly $3.50 per day, 5% less feed trampled in the manure saves $0.17 per cow per day representing a $64 per cow per year advantage for headlocks. One might speculate that a 5% difference in feed wastage would be noticeable in the manure and would have been reported, but this is not necessarily a safe assumption.

Preference observations suggest cows don't like headlocks, perhaps because they interfere with "flight from the boss cow" or because they are associated with a past painful "treatment or handling experience". If the 5% decrease in feed intake is real, and results in 3 Kg less milk, the milk cheque will be reduced by $1.70 per cow per day. Even if the reduced feed intake is deducted there is a disadvantage for headlocks of $1.53 per cow per day, or $560 per cow per year. That's more than enough to cover the cost of an alternative handling system, or even additional handling labour.

The best conclusion from this trial is probably that more research is needed. Nevertheless there will be numerous new barns built and decisions made about "head locks or no" before there is a final answer to this question. In practical terms the balance of the evidence suggests cows probably dislike headgates and eat less feed through them.

Producers building dairy facilities might want to consider including other cow handling systems such as management rails or sort lanes and pens.

If you already have headlocks, taking them all out may be premature. But you might consider giving high producing cows unrestricted manger access along most of their feed space. Another option is retractable headgates. With these gates, the bottom bar can be lifted to become the headrail of a post and rail manger when not needed for handling.

Efficient restraint and handling of dairy cows is an absolute necessity in the freestall barn. But feed intake is the force driving milk production and profitability. If these two issues are in conflict, I'll put my money on systems that put more feed into the cow.

This article first appeared in the April 2000 Ruminations column of the Ontario Milk Producer magazine.

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