17 January 2011

16 minute read

More than four of five dairy cows in the United States were raised on conventional dairy operations in which the majority of forage was harvested and delivered to the cows. About one of three operations was a combination of conventional and grazing operations types.

During the last 50 years, housing types on US dairies have changed from predominantly stanchion facilities to tie stalls, freestalls, and dry lots. In 2007, almost three of four lactating cows were housed in freestall or dry lot/ multiple-animal areas, and these cows were milked in parlor facilities. The more modern housing types allow cows more freedom of movement compared with the traditional tie-stall and stanchion facilities. Data from the Dairy 2007 study indicate that freestall housing provided an environment that promoted improved hygiene and reduced hock injuries; however, freestall facilities had the highest percentage of cows with lameness compared with other housing types. Unless allowed access to dry lots or pasture, cows in freestall housing were typically on concrete flooring, which may have contributed to the increased lameness reported.

On tie-stall and stanchion operations, cows have their own stall where they eat, drink, and rest, so space allotment in square footage per cow, cows per stall, feedbunk space, and cows per headlock is not applicable. In freestall housing, all cows are not typically doing the same activity, so it is not necessary to have the same amount of stalls, bunk space, or headlocks, if present, for all the cows in the pen.

Freestall features

The type of freestall barn impacts the ratio of stalls to feed bunk space or, if present, headlocks. Two- and four-row barns provide more feed bunk space and square footage per cow than three- or six-row barns. More than 6 of 10 freestall barns were two- or four-row barns. Research indicates that having up to 10 percent more cows than stalls in a pen (1.1 cows per stall) does not affect the cows’ behavior. At the time of the Dairy 2007 assessment, about 7 of 10 freestall operations had less than 1.1 cows per stall. However, when these operations were at maximum cow numbers, only 5 of 10 had less than 1.1 cows per stall. On freestall operations with headlocks, about one-third of operations had less than one cow per headlock at the time of the assessment, and when at maximum cow numbers, about one of six operations had less than one cow per headlock.

Stall management is important in providing a clean, comfortable place for cows to lie down. One of the most important aspects of stall management involves the stall base (floor upon which bedding is added) and bedding. Typical stall bases are composed of concrete, dirt, rubber mats, and mattresses. Straw, sawdust, sand, or combinations of the three were the most common bedding types for all housing types.

Stall base, bedding type, and management differed by housing type. Tie-stall and stanchion operations primarily used concrete, rubber mats, and mattresses as stall bases. In general, tie-stall and stanchion operations used straw or sawdust as bedding and changed or added bedding every 1 to 2 days. At the time of the Dairy 2007 assessment, the stall base was exposed—not covered by bedding—on about three of four operations with tie-stall and stanchion housing.

For operations with freestall and other multiple- animal area housing (including dry lots), the most commonly used stall bases were concrete, dirt, and mattresses. The most common bedding used on these operations were straw, sawdust, sand and, in the case of other multiple-animal areas, none. Bedding on freestall and other multiple-animal area housing was added or changed less frequently than on tie-stall or stanchion housing. However, even though these operations added/changed bedding less frequently than tie-stall or stanchion operations, at the time of the Dairy 2007 assessment the overall bedding quality/stall condition was better in freestall housing because a higher percentage did not have exposed stall bases.

Housing type did appear to have an influence on the health of dairy cows. Although freestall and other multiple-animal area housing improve production, hygiene, and reduce hock injuries, health problems still exist in these housing types. While more clinical mastitis, infertility, and displaced abomasums were reported on tie- stall and stanchion operations, a higher percentage of lameness was reported for cows on freestall operations. A lower percentage of cows on stanchion operations were permanently removed compared with cows on tie-stall or freestall operations. Mastitis accounted for a higher percentage of cow deaths on freestall operations and operations with other multiple-animal areas compared with stanchion operations.

Hygiene is important in reducing cows’ exposure to pathogens, especially in regard to mastitis and lameness. Features of cow housing generally thought to improve cow hygiene include bedding and bedding management, and the presence of neck rails, brisket locators, gutter grates, and cow trainers.

There were no differences by housing type in the percentages of cows with hygiene scores of 1 (clean). A lower percentage of cows had a hygiene score of 3 (dirty) on freestall operations compared with cows on tie-stall, stanchion, and dry lot operations. The higher percentage of cows with hygiene scores of 3 on tie-stall, stanchion, and dry lot operations might be due to the fact that cows on these operations typically have access to dirt or pasture. Hygiene on freestall operations, in which cows are not allowed on dirt or pasture, is dependent on freestall and alleyway management.

The use of concrete or rubber mats as stall bases was associated with poorer hygiene compared with the use of dirt or mattresses as stall bases. The use of coarse sand or dried or composted manure was associated with better hygiene compared with the use of other bedding types. Deep, well-bedded stalls were also associated with cleaner cows compared with stalls with less bedding. Moveable neck rails were associated with a higher percentage of cows with hygiene scores of 1, but the horizontal distance from the curb or the vertical distance from the bed did not influence cow hygiene. There were no consistent trends in the effect of brisket locators on hygiene scores; operations that used wood locators had a higher percentage of dirty cows compared with the operations that did not use any brisket locators. The use of gutter grates and cow trainers were both associated with improved hygiene.

Hock injuries are generally assumed to be related to the surfaces upon which cows lie. Cows housed in dry lot facilities and other multiple-animal areas where cows lie primarily on dirt had the highest percentage of cows without hair loss or lesions of the hocks (hock score=1). Hock lesions were generally more prevalent in tie-stall and stanchion housing types. Stall bases constructed of concrete, mattresses, and rubber mats were associated with increased hock lesions compared with dirt stall bases. Typical bedding types used in freestalls and facilities that generally do not use bedding (e.g., dry lots) were associated with better hock scores than facilities that bedded primarily with straw or sawdust (e.g., tie-stall and stanchions). Hock scores of 1 increased with the days since bedding was added, which was highly associated with housing type and bedding type. Fewer hock lesions were observed when bedding quantity was good and the stall base was not exposed than when bedding quantity was poor and the stall base was exposed.

Four comfort parameters were assessed during the study: perching (standing with the front feet inside the stall), standing (with all feet inside the stall), lying, and the cow comfort index (CCI), which is the proportion of cows in contact with a stall that are lying down. These comfort parameters were evaluated only on freestall operations or operations with other multiple- animal areas that included a combination of freestalls and other housing types, such as dry lots. Since cows spend almost 12 hours a day lying, it is important that they do not spend an inordinate amount of time perching or standing in the stall, although cows entering and leaving stalls are included in these two categories. Bedding type and management and specific stall features such as neck rails, brisket locators, stall length and width, and temperature have been shown to influence these parameters.

The percentage of cows perching increased when the stall base was completely covered with bedding, regardless of the type of stall base or bedding type. Although perching has been associated with shorter stalls and stalls with restrictive neck rails, neither impacted perching in this assessment. Curb height was associated with perching, as curb heights of 13.0 or more inches resulted in less perching, possibly due to increased proportion of weight being placed on the rear legs. Perching was also increased in summer months compared with spring months, likely due to cows attempting to dissipate heat during the summer.

Contrary to findings associated with perching, standing in stalls was not associated with bedding quantity but was associated with certain bedding types; a lower percentage of cows were standing in stalls bedded with straw, coarse sand, composted manure or no bedding compared with most other bedding types. Operations without neck rails had the lowest percentage of cows standing compared with operations with neck rails. Stall length did not impact standing. These were unexpected findings, since it was thought that less restrictive stalls (i.e., longer stalls, no neck rail) would lead to more cows standing in the stall.

A higher percentage of cows lying occurred on operations that used coarse sand as bedding compared with cows on operations that used straw, composted or dried manure, or “other” bedding types. In addition, a higher percentage of cows were lying when bedding had been changed/added within 1 to 2 days of the assessment than when bedding had been changed/added within 7 or more days of the assessment . Other features of bedding and stall management were not associated with the percentage of cows lying. Stall widths of 50 inches or more were associated with increased lying but stall length was not associated with lying. The absence of a neck rail was associated with a lower percentage of cows perching and standing and was also associated with a lower percentage of cows lying. Similarly, the absence of a brisket locator was associated with a lower percentage of cows lying. Curb height was also associated with lying, as curb heights of 13 inches or more were associated with a lower percentage of cows lying. The percentage of cows lying also decreased in summer compared with spring, which was likely due to improved dissipation of heat.

The CCI was higher for cows housed in facilities bedded with coarse sand compared with most other bedding types. The CCI was higher when bedding was level with the curb than when bedding was slightly dished out or more than 50 percent of the base was exposed. Season, which was associated with perching and lying, was also associated with the CCI, as a higher CCI was observed during the spring months.

Summary

Components of freestalls designed to keep cows comfortable, clean, and free of injury—such as neck rails and brisket locators—did not have much of an impact on hygiene, hock health, and comfort, which was unexpected. Stall base, bedding type and frequency, and bedding quality/stall condition were important for improving hygiene, hock health, and cow comfort. There also appears to be a trade off in keeping cows clean and keeping hocks healthy, as dry lots generally had dirtier cows but also had cows with much healthier hocks compared with cows housed in stalls. The findings in this report should assist in determining areas for improvement for each housing type, while also providing relevant information that may contribute to the development of new housing systems that provide optimal welfare for dairy cows.

The Dairy 2007 study marks the first time that the National Animal Health Monitoring System has studied parameters associated with cow comfort on dairy operations. A few highlights from this report follow. Almost one-half of operations (49.2 percent) housed lactating cows primarily in a tie-stall/ stanchion facility and nearly one of three operations (32.6 percent) housed cows in freestalls. However, almost 60 percent of cows were housed on freestall operations due to the fact that a high percentage of large operations use freestalls.

Concrete was the predominant flooring type on approximately one-half of operations and for 55.6 percent of cows. Pasture was the predominant flooring type on 10.1 percent of operations and for 5.1 percent of cows. Dirt was the predominant flooring type on 5.4 percent of operations and for 20.0 percent of cows, which likely reflects the use of dry lots on large operations. Heat abatement methods, including shade, fans, sprinklers, or misters, were provided during the summer months by more than 9 of 10 operations.

The following highlights refer only to operations that completed the facility, cow, and/or comfort assessments (see Section II, p 49).

About 8 of 10 operations used tie stalls or freestalls to house cattle. On average, stanchion barns were constructed in 1949 and were the oldest housing type. Freestall barns and other multiple-animal areas were constructed more recently than tie-stall barns. For all operations, 1976 was the average year of construction for all housing types.

A total of 69.6 percent of freestall operations housed fewer than 1.10 cows per stall at the time of the assessment. By design, tie-stall and stanchion operations housed one cow per stall. All tie-stall and stanchion operations provided 32 inches or more of bunk space per cow. In contrast, 57.1 percent of freestall operations provided less than the minimum recommended 24 inches of bunk space per cow at the time of the assessment. At maximum cow numbers (i.e., minimum feedbunk space), 67.9 percent of freestall operations provided less than the recommended minimum of 24 inches.

Hygiene scoring was performed on 477 operations. Freestall operations accounted for 282 of these operations and provided the majority (68.3 percent) of all cows scored. Approximately twice as many cows were scored on freestall, dry lot, and other multiple-animal area operations than operations with tie stalls or stanchions. These differences in animals scored among different housing types are directly related to herd size.

There were no differences by housing type in the percentages of cows with hygiene scores of 1 (clean). A lower percentage of cows had a hygiene score of 3 (dirty) on freestall operations (10.0 percent) compared with tie-stall, stanchion, and dry lot operations (16.2, 21.4, and 22.3 percent, respectively). Bedding type influenced hygiene scores. The lowest percentage of cows with a hygiene score of 3 were on operations that bedded stalls with coarse sand, composted manure, or dried manure (primarily freestall operations). As bedding quantity/stall condition decreased until the stall base was exposed, the percentage of cows with a hygiene score of 3 increased.

Freestall operations with stall lengths of less than 82.0 inches or 96.0 inches or more had a higher percentage of cows with a hygiene score of 1 (61.1 and 54.8 percent, respectively) compared with freestall operations with stall lengths of 86.0 to 91.9 inches (35.7 percent). The width of stalls did not have an impact on hygiene scores. The forward location of the neck rail was not associated with the percentage of cows by hygiene score. Operations with any gutter grates had a higher percentage of cows assigned a hygiene score of 1 compared with operations without gutter grates. The presence of cow trainers was also associated with cleaner cows; 50.3 percent of cows on operations with trainers had a hygiene score of 1 compared with 37.6 percent of cows on operations without trainers. Almost twice the percentage of cows on operations that did not use trainers had a hygiene score of 3 compared with operations that used trainers (23.6 and 14.1 percent, respectively).

No differences were observed in spring (March– May) and summer (June–September) in the percentage of cows by hygiene score. Hock scoring was performed on 477 operations; freestall operations accounted for 282 of these operations, providing the majority of all cows scored (67.9 percent). Approximately twice as many cows were scored on freestall, dry lot, and other multiple-animal area operations compared with operations that used tie stalls or stanchions. These differences in animals scored among different housing types are directly related to herd size.

Operations with dry lots and other multiple- animal areas had the highest percentage of cows assigned a hock score of 1 [no hair loss or swelling] (91.1 and 90.8 percent, respectively). Approximately three of four cows on freestall operations (76.8 percent) were assigned a hock score of 1, while tie-stall and stanchion operations had the lowest percentage of cows with a score of 1 (65.7 and 61.9 percent, respectively). Dry-lot operations had a lower percentage of cows with hock scores of 3 (swelling or skin lesion present) compared with tie-stall, stanchion, and freestall operations.

Almost 9 of 10 cows (89.5 percent) on operations that used dirt as a stall base were assigned a hock score of 1. The lowest percentage of cows assigned a hock score of 1 were on operations that used concrete, rubber mats, or mattresses as a stall base (72.8, 65.9, and 60.6 percent, respectively). The lowest percentage of cows assigned a hock score of 3 were on operations that used dirt as a stall base (0.7 percent), while the highest percentage of cows with a score of 3 were on operations that used concrete, rubber mats, or mattresses as a stall base (5.6, 7.2, and 5.0 percent, respectively).

A higher percentage of cows bedded with fine or coarse sand, composted or dried manure, or no bedding (primarily operations with freestalls, dry lots, or other multiple-animal areas) had hock scores of 1 compared with cows bedded with straw or sawdust (primarily tie-stall and stanchion operations). Similarly, a lower percentage of cows bedded in coarse sand and composted manure had hock scores of 3 compared with cows on straw, sawdust, or “other” bedding. As the number of days since bedding was added increased, the percentage of cows assigned a hock score of 1 increased. The percentage of cows by hock scores was associated with bedding quantity. As bedding quantity decreased until the stall base was mostly exposed, a lower percentage of cows had hock scores of 1. In addition, a higher percentage of cows had hock scores of 1 when no bedding was present than when the stall base was exposed.

The season in which assessments were made (spring or summer) did not impact hock scores. Comfort parameters were evaluated on 485 operations, and the pens and areas evaluated housed 52,490 cows. The majority of operations (290) and cows (39,014) assessed were on freestall operations. Four comfort parameters were assessed: perching (standing with the front feet inside the stall), standing (with all feet inside the stall), lying, and the cow comfort index (the proportion of cows in contact with a stall that are lying down) [CCI].

The percentages of cows perching were similar across all bedding types. Standing in stalls was observed for a lower percentage of cows when straw, coarse sand, composted manure, or no bedding was used compared with most other bedding types. A higher percentage of cows were lying in stalls bedded with coarse sand (48.0 percent) compared with stalls bedded with straw, composted or dried manure, or “other” bedding types (33.6, 30.2, 28.5, and 30.8 percent, respectively). With the exception of composted manure, the CCI was highest for operations that bedded with coarse sand compared with all other bedding types.

The percentage of cows perching in stalls was higher on operations in which the stall base was not exposed, bedding level with curb or slightly dished out (8.2 and 10.2 percent, respectively) compared with operations in which the stall base was less than 50 percent exposed (6.0 percent). Bedding quantity/stall condition was not associated with standing or lying parameters. The CCI was higher when bedding was level with the curb (74.2 percent) compared with bedding slightly dished out or more than 50 percent of the base exposed (63.7 and 66.2 percent, respectively).

The type or presence of a neck rail did not impact the percentage of cows perching or the CCI. A lower percentage of cows were standing in the stall when no neck rail was present (4.0 percent) compared with either the presence of a stationary or moveable neck rail (9.7 and 11.9 percent, respectively). Similarly, a lower percentage of cows were lying when no neck rail was present compared with operations with stationary or moveable neck rails. The presence of a brisket locator or the locator material did not affect the percentage of cows that were perching, standing, or the CCI. However, operations that did not have a brisket locator had a lower percentage of cows lying (32.6 percent) compared with operations that had brisket locators made of wood (41.9 percent) or PVC or other plastic pipe (46.4 percent). Season had a significant impact on the percentage of cows perching, lying, and on the CCI. The percentage of cows perching was lower in spring (March–May) than in summer (June–September), while the percentage of cows lying and the CCI were higher in spring than in summer.