Progress 10/01/02 to 09/30/05
Outputs
During the first phase of the project we examined the effectiveness of the different types of fans for cooling cows in the tropics (Koral Kool, 5hp; Schaffer fans, 1.5hp and oscillating fans, 1.0hp and 1.5hp). Respiration rates (number of breaths per min.) was used to measure the effectiveness of fans to cool high production lactating Holstein cows in the sub-tropics. Seventy breaths per min. was the physiologic "cut-off" indicator for heat stress. The Koral Kool system examined was effective if the animals could gain access to the wind movement or all cows under the fan were lying down. This system was expensive to operate. The Schaffer fans had lowest wind speed and pens that employed this system had lots of "dead space" where there was no air movement. Oscillating fans were able to distribute wind movement throughout the area under the roof. This system was able to maintain desirable wind speed (2.3m/sec) over 9m. The system was also least costly to operate. The
second phase of the project evaluated the role of hair color on longevity of cows in the sub-tropics. It was found that cows with black hair coat (>80% black) had greater longevity than cows with white hair coat (>80% white). Regression analyses with number of lactations on x-axis and hair coat color (% in herd) showed that as parity increased so did the % of black cows in the herd increased (p<0.01). There was no difference in milk production. Black animals had shorter and finer hair than white. It was also observed that white cows without pigmentation in the eye teared and stained their face. Cooling by the use of water was effective in extending the time a cow lay down to rest. Dorsal skin temperatures measured by handheld infra-red thermal gun also showed that cows were most likely to rise and seek heat stress relief at 96-98F. Respiration rate of 72 breaths per min. was critical to trigger a Holstein cow to seek relief from heat stress.
Impacts
The first phase of this research showed that not all fans are equal. The manner fans are placed and their ability to distribute air movement evenly across a wide area under shade are important. Another factor is the cost of operating such environmental modifies. Oscillating fans were found to be most effective when these factors were considered. Strangely, black cows tend to last longer in dairy herds in the sub-tropics. The black surface of the skin enhance evaporative heat loss. Lastly, dorsal skin temperatures (96-98F) or respiration rates (>72 breaths per min.) can be a physiological guide to determine if a cow is in heat stress in the sub-tropics. Both these physiologic events can be measured by a farmer without having to employ cost tools.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
Studies evaluating various environmental modifiers (shade alone, shade+fans+misters, shade+fans and shade with feedline foggers) were conducted with 3 dairies within 0.5 miles apart. Respiration rates (RR) for lactating cows were highest for summer (Aug-Oct) vs lower in winter (Dec-Feb). Cows under shade+fans+misters had lowest RR (50s counts per min.), followed by cows at the manger where they were wetted by feedline foggers (low 60s counts per min.) while cows with shade alone had RR averages in the low 80s with summer readings above 90 breaths per min. The RR were also higher in the pm (1300-1500h) vs am (0900-1100h). In the systems with shade+fans+misters, Koral Kool cows had lower RR compared to oscillating fans. Milk production were significantly higher for the cows in this dairy. While feedline foggers are effective in cooling cows, two major issues arose with the farm employing such techniques: a) problems with wastewater management, and b) higher incidence of
foot problems reported in the farm. The latter is probably due to longer hours spent standing on wet floors. The hoof problem warrants further investigation. Providing shade for cows in hot-humid areas like Hawaii, reduced the actual THI load on the cow by 3-5 units (THI in shade vs THI in open). In addition, we monitored the skin and rectal temperature of cows at the feed manager after milking. If the animals were provided with shade over the manger/head locking stanchion, rectal temperature (RT) of the first 20 vs the second 20 cows did not differ. However, in the absence of shade, there could be 1-1.5 degree F higher RT in the second 20 cows i.e. 101F vs. 102.2F.
Impacts
In hot-humid regions, providing shade to Holstein cows or high production cows will reduce heat load. However, this is in itself insufficient. Water is an excellent medium to cool cows at the stanchion. Heavy use of water at the feed manger can result in wastewater management problems, especially in light of CAFOs and AFOs. Potentially, there can be a higher incidence of hoof problems due to extended standing and softening of the claw. Further investigation is warranted. Fans and mister under shaded areas are most efficient in cooling cows. The animals will have normal respiration rates and rectal temperatures. There are differences in the abilities of fans to cool cows but the economics of the capital improvements and subsequent operations need to be evaluated. Important variables would be the price of milk on farm and the cost of energy.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
Studies on the effect of hair coat on longevity showed that over 50% of multiparous cows have hair coat that are 80% or more black. The percentage of these cows increase the sub-population of a herd with increasing lactations. However, the population of white cows (>80% white) decreased with increasing population. While milk production was not different between white, black or black/white (50:50) cows, the greater longevity suggest black cows in the sub-tropics may be more profitable. Statistical risk evaluation confirmed that white cows were leaving the herd at a faster rate. Hair obtained from black cows were shorter and more fine while white hair yielded 2x the weight due to coarser texture and length. Black cows also had black/dark grey skin while the white cows had pink skin and this may affect their longevity. In addition, we have completed evaluation of respiration rates, skin temperatures and rectal temperatures from cows under various cooling systems. The
data are currently being analyzed.
Impacts
The data from the above study suggest that it may be prudent to select or breed for hair coat and skin color if dairy operations are in the sub-tropics and tropical regions. Since tremendous cost in dairy operations is associated with raising dairy heifer replacements, longevity and productivity of a lactating animal can determine profitability of an operation.
Publications
- Lee, C.N., Baek, K.S. and Parkhurst, A. 2003. Hair coat color may influence longevity of Holstein cattle in the tropics. J.Dairy Sci. 86 Suppl. 1 (#77).
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Progress 10/01/01 to 09/30/02
Outputs
No progress to report. This project was initiated on October 1, 2002.
Impacts
(N/A)
Publications
- No publications reported this period
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