*4.1.4 Lugol's iodine*

Intrauterine application of Lugol's iodine can effectively induce estrus in cattle, buffalo, etc. [12, 13]. A dose of 20–30 ml is sufficient for treatment. It also shows a good conception rate with cost-effectiveness. It actually acts as uterine irritant and increases blood supply there. It can also stimulate the hypothalamus for the secretion of GnRH, and thus the reproductive cycle is regained [13].

## **4.2 Hormonal treatment**

#### *4.2.1 Estrogen*

Estrogen is a very important hormone for the reproductive cycle of the animals. Administration of estrogen can help the animal to come into estrus [1], though it may be ovulatory or anovulatory. If a dominant follicle is present in the ovary, there will be ovulation. If no dominant follicle is present, it can be anovulatory. Estrogen promotes the ovulation through LH surge as estrogen shows a positive feedback effect toward the pituitary at this time. Use of estrogen is limited nowadays due to its side effects. Prolonged administration of estrogen can cause cystic ovary, peristalsis of the oviduct, etc. [1]. These can also lead to several infections like ovaritis, adhesion, etc.

#### *4.2.2 Progesterone*

Progesterone is secreted from the corpus luteum in a normal estrus cycle. With the decrease in the progesterone level, the follicles start growing. The same situation can be mimicked externally. Progesterone can be administered externally for a certain duration, and its withdrawal can cause induction of estrus. Several intravaginal progesterone-releasing devices are available. It includes CIDR (controlled internal drug release), PRID (progesterone-releasing intravaginal device), etc. Ear implant of progesterone is also available. These devices are generally used for 7–9 days and can be combined with other hormones like GnRH, prostaglandin F2α (PGF2α), etc. [1]. Other ways to use progesterone are oral progesterone compound and intramuscular injection.

### *4.2.3 GnRH*

GnRH and its analogues can be successfully used to induce estrus in animals. It induces ovulation, if mature follicle is present by inducing the LH surge. GnRH can improve conception at the timed artificial insemination (Al) after estrous synchronization with prostaglandin F2α [14]. GnRH given after PGF may enhance fertility through its direct or indirect (via LH secretion) action on the ovulatory follicle, and it may act in a similar fashion at insemination after spontaneous estrus [15]. Gonadotropin-releasing hormone improved fertility at first postpartum inseminations in some studies [15], but not all investigations [16]. Increasing progesterone after insemination may be one way to improve fertility in cattle. It is possible that LH released by GnRH could enhance fertility through its effects on luteal function [17].

### *4.2.4 Prostaglandin*

For persistent corpus luteum and subestrus, PGF2α is the treatment of choice. Successful management of silent estrus in cattle and buffaloes can be done by the

**139**

*Induction and Synchronization of Estrus DOI: http://dx.doi.org/10.5772/intechopen.90769*

subestrus or unobserved estrus.

*4.2.5 Insulin*

effective [24].

*4.2.6 Anti–prolactin*

natural or synthetic analogue of PGF2α as a single dose with a reasonable degree [18, 19]. PGF2α is only effective between days 6 and 16 of the cycle and in the presence of active corpus luteum. Administration of 25 mg of natural PGF2α intramuscular or 250–500 μg of synthetic ones is required to regress the CL in both cattle and buffaloes [1]. Pursley et al. [20] described Ovsynch protocol may be used to treat

Encouraging results have been found in the use of insulin for induction of estrus in animals either alone or in combination [21–23]. The recommended dose is 0.25 IU/kg body weight subcutaneously for 3–5 days. Promising results for management of anestrus in cattle have been observed with the use of GnRH or eCG pretreated with insulin [22, 23] and buffaloes [21, 24]. Insulin enhances the follicular growth in true anestrus buffalo which is a prerequisite for GnRH to be

Summer anestrus in buffaloes could be due to hyperprolactinemia, with this assumption bromocriptine, an anti-prolactin drug [25], has been used. Melatonin is also known to suppress prolactin secretion [26]; however, melatonin has been reported as stimulator of both GnRH and gonadotrophin secretions in buffaloes. As the plasma concentration of melatonin is low during summer, induction of estrus and ovulation by using melatonin implants have been reported by Ghuman et al. [27] in all treated summer anestrus buffalo heifers; however, the time taken to induce

The manipulation of the estrous cycle or induction of estrus brings a large percentage of a group of females into estrus at a short, predetermined time [28]. One of the advanced managemental processes through which the humane errors and managemental costs could be minimized is synchronization of estrus. It is predominantly useful in sheep, where timely heat detection is difficult due to exhibitions of less external heat symptoms and also in large herd of cattle. It helps in fixing the breeding time within a short predefined period and thereby scheduling the parturition time at the most favorable season in which newborns can be reared in suitable environment with ample food for augmenting their survivability. As timely breeding of the animals is possible with this technique, fertility in farm animals may be expected toward the upper side. By improving the production efficiency of animals,

estrus synchronization provides more economic returns to the owner.

with the follicular development manipulation.

Synchronization can shorten the breeding period to less than 5 days, instead of females being bred over a 21-day period, depending on the treatment regimen. Production of a uniform group of calves for the future replacement in the animal farm is another important benefit of this program. The current and future aspect of estrous synchronization is to focus on combining traditional methods of controlling cycle length with the follicular development manipulation. The combination of GnRH with the prostaglandin F2α [20]- and progesterone [29]-based synchronization program has shown a novel direction in the estrus synchronization of cattle

estrus and ovulation was highly variable (4–36 days).

**5. Synchronization of estrus**

natural or synthetic analogue of PGF2α as a single dose with a reasonable degree [18, 19]. PGF2α is only effective between days 6 and 16 of the cycle and in the presence of active corpus luteum. Administration of 25 mg of natural PGF2α intramuscular or 250–500 μg of synthetic ones is required to regress the CL in both cattle and buffaloes [1]. Pursley et al. [20] described Ovsynch protocol may be used to treat subestrus or unobserved estrus.
