Incidence of postpartum anoestrus
The incidence of postpartum anoestrus in 1000 Lakhimi cows was found to be 20.60%. Almost similar findings (20.30%) in crossbred cows were reported by
Dutta et al., (2019b). The incidence rate of postpartum anoestrus in indigenous cows of Assam was 18.93% as reported by
Chhetri, (2018). However lower incidence rates (16.42%) in crossbred cows were reported by
Acharya, (2016).The higher post partum anoestrus (28.00%) in dairy cows was recorded by
Selvaraju et al., (2009). The variation in the incidences of postpartum anoestrus might be due to feeding practices, genetic makeup of the animals, nutritional status, age, area of study and housing patterns of the animals
(Dutta et al., 2019b).
Response to various hormonal and nutritional interventions
Oestrus induction response
The oestrus induction responses in various treatment regimes in Lakhimi cows were illustrated in Table 1. It was observed that oestrus induction response was found to be higher in the group treated with Clomiphene citrate + Mineral mixture and the lowest in control group. The oestrus induction response in postpartum anoestrous Lakhimi cows treated with hydroxyprogesterone caproate + eCG estimated in the present study was similar (83.33%) to
Chhetri (2018) in anoestrous indigenous cows treated with progesterone + eCG. On the other hand, higher oestrus induction response (90.00%) was reported by
Honparkhe et al., (2008) in true anoetrous cows treated with hydroxyprogesterone caproate +eCG. The variation in the percentage of induced oestrus in different studies might be due to doses of hormones and resumption of follicular development and its maturation after treatment.
The oestrus induction response for Clomiphene citrate treated group was found to be 33.33% in the present study. Clomiphene citrate bolus orally daily for five days showed oestrus induction response 50.00%
(Mangrole et al., 2018), which was higher than the present investigation. The percentage of oestrus induction response recorded pertaining to Clomiphene citrate + Mineral mixture treated cows in present findings (100.00%) was higher than the findings of
Mangrole et al., (2018) in postpartum anoestrous crossbred cows (66.66%) treated with Clomiphene citrate and mineral mixture. In the present study lower oestrus response in the cows treated with Clomiphene citrate alone might be attributed to the non-supplementation of mineral mixture.
The oestrus induction response rate following GnRH treatment cows in the present study was similar (50.00%) with the findings that recorded by
Dutta et al., (2019a) in anoestrous cows. The rates of oestrus response following GnRH analogue injection were reported as 66.67%
(Chhetri, 2018) in post partum cows. However, lower oestrus response (33.33%) was recorded by
Gupta et al., (2010) in cows treated with GnRH. The variation in the oestrus response in different studies might be due to different body condition of cow, feeding management, climatic condition and potency of GnRH hormone used in the study. The oestrus induction response recorded pertaining to GnRH analogue + Mineral mixture treated cows in the present study was similar (66.67%) to the finding of
Chhetri, (2018) in postpartum anoestrous indigenous cows treated with GnRH + bypass fat + minerals + vitamins. On the other hand, lower oestrus induction response 50.00% was recorded by
Mangrole et al., (2018) in crossbred cows treated with GnRH analogue + Mineral mixture. However, higher oestrus response (83.33%) was recorded by
Dutta et al., (2019a) in true anoestrus crossbred cows treated with GnRH analogue + Mineral mixture. These variations might be due to differences of breed, general health of animal and climatic variations.
Cows treated with Mineral mixture alone in the present study showed 66.67% oestrus induction response which was nearer (70.00%) to the findings of
Jana et al., (2015). The higher oestrus induction response was recorded by
Noonari et al., (2016) and reported 100.00% oestrus induction response in crossbred cows treated with mineral mixture. On the other hand, lower oestrus induction response (50.00%) was recorded by
Chaudhiry et al., (2019) after treated with mineral mixture. Mineral supplementation might show beneficial effect on postpartum ovarian activity by increasing number of ovarian follicles along with follicular growth. But the differences in oestrus response might be due to body condition of animal, parity of animal and season of study.
Interval from end of treatment to onset of oestrus
The mean interval from end of treatment to onset of oestrus in postpartum anoestrous cows treated with different treatment regimes are presented in Table 2. Statistical analysis indicated that the mean interval from end of treatment to onset of oestrus differed significantly between different treatment regimes. In Hydroxyprogestero ne caproate + eCG treatment protocol of present study, the mean interval for onset of oestrus from the end of treatment was in accordance with
Chhetri, (2018). The mean interval from the end of treatment to onset of oestrus as 50.00 ± 0.52 hours in the cows treated with progesterone + eCG as reported by
Chhetri, (2018). However,
Kasthuri (2006) reported higher mean interval from end of treatment to onset of oestrus (3.65±0.23 days) in crossbred cows treated with Folligon injection (PMSG) as compared to the present study. The variation in the values in different findings might be due to doses of eCG (PMSG) and incorporation of different drugs before PMSG therapy.
The mean interval from the end of treatment to onset of oestrus in Clomiphene citrate alone and Clomiphene citrate + Mineral mixture protocol was comparable with findings that observed by
Bawaskar et al., (2017). The mean interval from the end of treatment to onset of oestrus was recorded to be 4.33±0.91 days
(Bawaskar et al., 2017) in the animals treated with Clomiphene citrate bolus @ 300 mg orally daily for 5 days.
The mean interval from the end of treatment to onset of oestrus in GnRH analogue treatment protocol in the present study was found to be higher than that of
Dutta et al., (2019a). The mean interval from the end of treatment to onset of oestrus was recorded to be 12.67±7.31 days
(Dutta et al., 2019a) in cows treated with single injection of GnRH analogue. However, mean interval from the end of treatment to onset of oestrus in GnRH analogue + mineral mixture protocol of present study was found to be higher than the findings recorded by
Dutta et al., (2019a) in true anoestrus cross bred cows (5.00 ± 1.05 days). GnRH hormone efficacy depends upon availability of recruited ovarian follicles.
The mean interval from the end of treatment to onset of oestrus in mineral mixture alone treatment was nearer with findings that observed by
Selvaraju et al., (2009).The induction of oestrus in dairy cattle within 2 months while supplemented with area specific mineral mixture as reported by
Selvaraju et al., (2009). These differences might be due to stage of reproduction of experimental animals, geographical variation, general health of the animal and variation of doses of therapy used.
Conception rate
Conception rates based on number of cows induced to oestrus and cows treated with different treatment regimes are presented in Table 3. The conception rate recorded pertaining to Hydroxyprogesterone caproate + eCG treated cows in the present study was zero which was lower than
Chhetri, (2018). The conception rate was 40.00% in cows treated with progesterone + eCG
(Chhetri, 2018).
The conception rate for Clomiphene citrate alone in postpartum anoestrous cows was found to be 33.33% which was lower than the earlier records (50.00%) in cows treated with clomiphene citrate alone orally daily for 5 days as reported by
Mangrole et al., (2018). The conception rate based on the number of treated animals following GnRH treatment protocol in the present was similar to that reported by
Gupta et al., (2010). However higher conception rates 67.70%
(Islam et al., 2013) and 50.00%
(Dutta et al., 2019a) was reported in cows with GnRH treatment. The conception rate based on the number of treated animals following GnRH analogue + Mineral mixture protocol was similar (50.00%) to that reported by
Dutta et al., (2019). However, there was lower conception rate (33.33%) as compared to the present study with GnRH analogue + Mineral mixture was recorded by
Chhetri (2018) in postpartum anoestrous cows.
The cows in the present study treated with mineral mixture protocol showed 33.33% conception rate in postpartum anoestrous cows which was comparable (35.00%) to that reported by
Das et al., (2016). Sahoo et al., (2016) reported 55.00% conception rate in crossbred cows treated with bypass fat @ 100 g/day/animal along with mineral mixture @ 50 g/day/animal.
The lower conception rate in Hydroxyprogesterone caproate + eCG, Clomiphene citrate and GnRH analogue in the present study might be due to non-supplementation of mineral mixture, genetic makeup of animal, environmental and managemental factors and season of study.