Important Reproductive details / Breeding guidelines


Estrus Period
 Pro estrus: 2 or 3 days
 Estrus: 12 to 18 hours
 Ovulation: 12 to 16 hours after the end of estrus
 Estrous cycle length: 21± 3 days


Puberty
 Puberty is the stage at which animal becomes sexually mature and secondary sex characteristics become conspicuous.
 The term sexual maturity means that the animal is capable of reproduction.
 Puberty is the age at which the first estrus occurs in the heifer and the bull starts giving semen with viable sperms.
 The reproductive organs undergo marked increase in size at the time of puberty.
 Under good feeding a calf attains puberty approximately at 66 per cent of adult body size.

Signs of estrus
 Cow in estrus will be the first cow to rise in the morning.
 The cow become restless does not eat and frequently bellows and seldom ruminates.
 Sudden drop in milk production.
 Searching for male.
 Traits of homosexuality is shown in which the cow will attempt to mount other cows while other females not in estrus tend to mount the estrus cow which she permits.
 The cow is receptive to the act of mating and will stand when the bull mounts her.
 The behaviour of standing quietly while being mounted by the bull or other cow is referred to as the ‘standing heat’ which is the surest sign of estrus.
 This extends for 14-16 hours and shows other symptom like bellowing, nervousness, anorexia, reduction in milk yield.
 Mucous discharge may be found sticking to the tail.
 In early heat the discharge is watery and copious in mid heat (standing heat) it becomes thick and sticky and in late heat it will be scanty and discoloured.

Other methods to detect estrus
 Crystallization pattern of cervical mucous will show long crystals in a typical fern-like pattern
 There are many estrus-detecting devices available. They are usually attached to the tail or rump of the cow.
 Mounting causes these devices to discharge a coloured fluid which can be observed afterwards even from the distance.
 ‘Chin ball mating device’ can be used for heat detection. It works on the same principles of a ball point pen and is fixed by means of a halter below the chain of the teaser bull. When the checking animal mount the cow in heat, the dye exuded round a spring-loaded ball of the device marking the back of the cow.
 Russian workers have developed an instrument basically consisting of an ohm meter and electrodes. When applied to the mucous membrane of the vagina, the resistance indicated on the ohm meter shows whether the cow is in heat.
 Pedometer is an instrument used to monitor the movement of animal. The principle is the activity and movement of the cow increases on the day of heat and this can be detected by means of a pedometer tide to the leg of the cow.
 The vaginal temperature can be recorded, which gives an indication about the heat. Generally during estrus, the vaginal temperature increased by about 1°Con the day of heat. Both methods are not very practicable.
 The methods described above had little applicability in developing countries due to technological and economical and managemental reasons.
 close observation of signs of heat, standing heat remains the most practicable method of heat detection.
 In large farm this can be supplemented with a bull-parade using a teaser bull. A teaser may be a vasectomised bull or bull in which penis has been amputated and the urethra exteriorized.
 An intact bull can also be used by hanging a thick cloth or gunny bag curtain in front of the penis preventing entry of penis and mating.
 Special care should be taken to prevent spread of disease by teasers. Vasectomised bull is more harmful in this regard.

Time of insemination
 Ovulation takes place about 12 hours after the end of estrus. It takes another six hours for it to travel half-way down the oviduct.
 The sperm, even though reach the oviduct within minutes after insemination, must be exposed to the female reproductive tract for about 6 hours to attain the capacity to fertilize.
 This process of preparing the sperm for fertilization is known as capacitation.
 Sperm are viable for 24 hours in the female reproductive tract whereas the ovum remains fertile for only about 10 hours after ovulation.
 This implies that mating or insemination between mid-estrus (middle of standing heat followed by another insemination in about 6 hours after that.
 As a routine practice, if a cow is seen showing signs of early heat in the morning, it may be inseminated in the evening.
 If such signs are first manifested in the evening, the cow may be bred next day morning.
 A cow is expected to show estrus in 30-40 days after calving. Cows that fail to show heat even after 50 days have generally some problem and need examination.
 It may be due to infection or malnutrition and remedial measures may be taken accordingly.
 Insemination should be done only when buffalo is in standing heat. In buffalo to understand standing heat one should know the symptoms of heat.
 Buffaloes normally are not seen standing for mounting by herd mates but standing heat can be known from the changing colour of mucus discharge which is early estrus is clear and watery but in standing heat or mid heat the colour is changed to little buffy with thick consistency.
 In mid heat the oedema of vulva is intense there is little gap in vulvar lips and lower lip looks oily.  The vulvar mucus membrane is glossy reddish or pink and wet.

Signs of approaching parturition
 Cow will leave the herd and seek isolation.
 Loss of appetite and distress.
 Distension of teat and udder, considerable milk appears in the udder and there may be dripping of milk.
 Relaxation of pelvic ligament one day before calving, the ligament on the sides of the tail head is loosened so that hollows appear on either side of the backbone and the tail head is raised and the quarters are dropped.
 The vulva become enlarged and flabby
 Animal will be restless and will pace about often trying to kick or scratch the flank region.
 The parturition process has three stages a. preparatory stage (uterine contraction and dilatation of cervix) b. active expulsive stage c. expulsion of foetal membrane.
 Cow will deliver the calf within 12 hours after commencement of first stage and lapse in this vaginal examination of assistance by a veterinarian is required.
 Care must be taken to observe expulsion of placenta (after birth). It should be removed immediately so as to avoid cow eating it.