Silent Heat Problems

In this condition animal will not show behavioral signs of estrus although the physiological symptoms of heat will be present. Although the general pattern of sexual behavior is almost similar in cattle and buffaloes but the intensity of expression of behavioral signs of estrus in buffaloes is markedly less pronounced especially during summer months as the buffaloes are relatively inefficient to maintain their thermoregulation under increased environmental temperature and at high relative humidity. So due to this reason buffaloes are in constant heat stress during summers which causes the suppression of behavioral signs of estrus. The behavioral sign of heat such as bellowing may be absent and the heat is therefore termed as silent. In addition to this the other behavioral signs of estrus such as mounting to fellow animals and allowing other animals to mount, restlessness may also be expressed in much diminished intensity.

The vulva of buffalo in heat will be slightly swollen and slight radish in colour as well as a string of mucus found hanging from the vulva or present inside vulval lips is a sure sign of heat in summer season. However the behavioral signs of estrus are more pronounced during cooler hours of the day especially during early morning and late evening. So the buffalo in estrus can be detected by parading a teaser bull during these periods and also by close observation by a trained person during early morning hours. The incidence of silent heat has been found to be more in cows and buffaloes, which were neither allowed for grazing nor given any exercise, and being kept on concrete floors. The animals that are not given sufficient protective measures from the extremes of the weather are most sufferers.

In cattle the incidence of silent heat is found to be more in high producing cows while in heifers the silent heat is highest in those heifers that are low in position in the social hierarchy of the herd. If   grouping of cows have been made without considering the ranks of cows in the herd this will results in decrease in efficiency of heat detection as the submissive cows may avoid mounting to dominant cows. In addition to this also the incidence has been found to be high when group size is very large in which there is ongoing social conflicts and that will result in to instability to social hierarchy.

Solutions to Overcome Silent Heat Problem

This problem can be overcome by removing different constraints such as allowing animals for grazing or left them loose for few hours where the animals have been tied. There should be provision of non-slippery or kuccha floors to facilitate the mounting activity of the cows that are in estrus. In summer season water should be sprinkled over the body of the animals for 5-10 minutes twice or thrice daily or allow them to wallow for two hours daily in the morning and in the evening to alleviate the impact of heat stress. At large organized dairy farm mistress cooling system installed inside the shed is found to be very effective in maintaining normal estrus behavior of buffaloes and cross-bred cows. If the roof are made up of asbestos or iron sheet then spread some paddy straw over it make wet by sprinkling of water. Animal should be fed green fodder and the feeding must be done during cool hours of the day. During summer the feed intake of the animal is reduce so the quality of the ration should be improved in order to fulfill their physiological needs. In addition to this there should be improved or efficient methods of heat detection. A combination of methods is better than relying on a single method of heat detection. Visual observation should be performed by trained persons during cooler hours of the day especially during early morning and late evening as the behavioral signs of estrus are more pronounced during this period. Parading of teasure /vasectomized bull during early morning and late evening.

Heat Detection

A bull will always notice a cow in heat and will serve her if there are no boundaries between the bull and cow. Many cows have heat signs that are difficult to notice for humans. The heat signs that humans can see are:

  • The animal becomes restless, sometimes separating itself from the rest of the herd, walking along fences to seek a bull.
  • The animal tries to mount other animals, sniffs them and is sniffed at by others (see figure)
  • The animal bellows in order to attract a bull (the Zebu does not do this).
  • Standing heat: the cow stands still when she is mounted by other animals (standing is the only reliable practical test of heat, see figure).
  • Signs that the animal has been mounted by others, such as mud on its flanks, bare patches of skin on the hook or the pinbone, ruffled hair on the back etc. (see figure).
  • The lips of the vulva turn red and are somewhat swollen (see figure).
  • There is a discharge of clear, thin mucus hanging from the vulva or adhering to the tail (see figure).

Heat Detection

The average heat period lasts about 11 hours, so in order to detect heat you should check the cows at least 3 times a day: early in the morning, in the afternoon and late in the evening (spend about 20 minutes each time). Cows should be calm (not distracted by feeding or so).

Heat Detection