Dr. Bill Weiss, Dairy Nutrition Specialist, The Ohio State University
At this year's Federation of Animal Science Societies (FASS) annual meeting, several presentations were given on management and facility factors that can affect feeding behavior and dry matter intake. One study conducted at the University of British Columbia examined how stocking density (inches of feed bunk space per cow) and type of feed barrier (post and rail vs. headlocks) affected cow behavior. On average, Holstein cows in a post and rail system spent 20 more minutes per day eating than cows fed with headlocks (a 7% increase). With both systems, eating time decreased as bunk space decreased (Figure 1). Going from 1 headlock per cow (24 inches of bunk space) to 1 headlock per 3 cows (8 inches) decreased eating time by 17%. That was the same percentage decreased observed when bunk space decreased from 24 inches to 8 inches with a post and rail system. Cows with 16 inches of bunk space in a post and rail system spent the same amount of time eating as did cows with 24 inches of bunk space in a headlock system (1 headlock/cow).
Figure 1. Effect of bunk space and feeding system on eating time by lactating Holstein cows. With the headlock system, 24 inches = 1 headlock/cow, 16 inches = 2 headlocks/3 cows, and 8 inches = 1 headlock/3 cows. Data from Huzzey et al., 2005. J. Dairy Sci. 88 (Suppl. 1): 392.
Cows that spend less time eating must either reduce dry matter intake (intake was not measured in this experiment) or increase their rate of consumption (i.e., more feed consumed per minute spent eating). Both of these can have negative effects on productivity. Reduced feed intake usually results in decreased milk yields and/or excessive loss of body condition. Cows that consume feed too rapidly are at risk for ruminal upsets. These data suggest that if cows are moderately crowded, a post and rail system may be better than a headlock system with respect to feed intake and ruminal health (headlocks have advantages when working with cattle that must also be considered). Severe crowding in both systems most likely will result in reduced feed intake and increase the risk for rumen acidosis.
The effect of feeding frequency was examined in another study conducted at the University of British Columbia. Cows had 24 inches of bunk space and were fed either once, twice (about 8 hours apart), or 4 times (about 6 hours apart) per day. For cows fed once daily, feed was pushed up 3 times/day and for cows fed twice daily, feed was pushed up twice per day (feed pushing occurred at the same times as cows in the 4 X group were fed). Compared with cows fed once daily, feeding twice daily increased eating time by 10 minutes/day (about a 3% increase) and feeding 4 times increased feeding time by 24 minutes (an 8% increase). These rather modest increases in eating time may not be adequate to justify the increased labor costs of more frequent feeding. Whether these responses would be the same when cows are crowded (< 24 inches of bunk space) is not known.
The effect of amount of feed refusal on eating behavior and intake was examined in a study conducted at the University of Idaho. They fed Holstein cows (average production about 90 lb/day of milk) the same diet to two groups of cows. One group was offered enough feed so that about 5% was remaining 24 hours later (actual refusal was 5.5%). The other group was offered enough feed so that about 2.5% was remaining 24 hours later (actual weighback was 3.4%). Feeding for less refusal did not affect milk production or dry matter intake (averaged 57 lb), but it did affect eating patterns. Eating time was reduced by almost 60 minutes/day, and the rate of eating (grams of dry matter per minute) was increased by almost 25% for cows fed for low feed refusal. Although feeding for less feed refusal will reduce feed costs, it may increase the risk for acidosis because of the increased rate of feed consumption. This should be considered before implementing this feeding program.