The floor of the dairy housing is an important feature and has been identified as a risk factor for development of hoof and leg lesions. Flooring type, consistency and how it is presented can affect the comfort of cows. Studies presented here examined 3 features: the slope (Chapter 2), roughness (Chapter 3) and compressibility of the standing surfaces (Chapter 4), with the objective to evaluate the effect of standing surface characteristics on dairy cow behavior and muscle physiology in order to improve cow comfort. In combination, restless behavior measures by steps/min, latency to lie down after standing, and a novel technology, surface electromyograms (SEMG) were used to evaluate of cow comfort while standing.
First experiment evaluated floors with 0, 3, 6, or 9% slope during and after 90 min of standing. The number of steps/min and total muscle activity increased significantly over 90 min of standing, irrespective of floor slope and both behavior or SEMGs could not detect treatment differences. Out of the 2 muscles tested middle gluteal muscle had higher Median power frequency (MPF) compared to biceps femoris indicating that the contractive properties of these muscles differ. Although restless behavior and muscle function did not change with slope, this work demonstrated that EMG can be used to measure leg muscle activity in cattle. Therefore this methodology was used in the 2nd experiment on a compromised standing situation, when cows stood on rough floors under all 4 legs or just 1 hind leg. Three treatments: smooth concrete under all 4 legs (0-ROUGH), rough surface under all 4 legs [2 cm X 2 cm X 4 cm trapezoidal protrusions (4-ROUGH)] and the same rough surface only under 1 hind leg, with other legs on smooth concrete (1-ROUGH) were tested. The number of legs subjected to roughness influenced both behavioral and physiological responses to rough flooring. Cows on 1-ROUGH stepped twice as often with the rough-treated hind leg and half as much with the non-rough-treated leg compared to other floors. Similarly, on the 1-ROUGH surface, total muscle activity was reduced in the rough-treated leg, and muscle activity was more sustained (3x higher) in the non-rough-treated leg, suggesting that cows avoid potential discomfort under 1 leg by using muscles in the non- rough-treated leg. In the 4-ROUGH treatment, a different pattern was observed. Time between steps was more variable than on the other 2 treatments, likely because cows could not escape the potential discomfort in the 4-ROUGH treatment. Thus, the protocol used to evaluate comfort while standing altered the response. Steps/min and SEMG changed when roughness was under a single leg, while timing between consecutive steps changed with rough flooring was under all 4 legs. Because, the protocol of having roughness under 1 leg affected both behavioral and muscle activity changes, the same protocol was used in the third experiment to compare different compressible floors (concrete and rubber). Four standing surfaces that varied in floor type (Concrete and Rubber) and presentation of the floor (same floor under all 4 legs: ALL4CON and ALL4RUB , rough surface only under 1 hind leg, with other legs on smooth concrete; 3CON/1-ROUGH and 3RUB/1-ROUGH) were compared in a 2x2 factor design. No interaction between floor type and presentation was observed. There were significant presentation effects where both 1-ROUGH surfaces indicated similar findings as seen in the second experiment. Restless behavior patterns could not differentiate between floor types. Muscle activity movements among legs increased over time on concrete floors compared to rubber indicating a potential avenue on future research in comparing compressibility of the surfaces.
These experiments identified several limitations of using restless behavior as an indicator of discomfort. Counting steps form individual legs and looking at stepping patterns can provide valuable insight to roughness under the legs. Discomfort can be detected by muscle activity. Muscle activity movements between legs show promise in evaluating standing surfaces. All these experiments could not detect muscle fatigue in cows and future research with different methodological approach is required in this regard.
|Advisor:||Tucker, Cassandra B.|
|Commitee:||Mench, Joy A., Millam, James R.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 76/02(E), Dissertation Abstracts International|
|Subjects:||Zoology, Animal sciences, Behavioral Sciences, Physiology|
|Keywords:||Behavior, Dairy cattle, Flooring, Muscle physiology, Surface electromyogram, Welfare|
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