The fortnightly mean (±SE) values of various hormonal parameters obtained in different groups of parturient Gir cows are presented in Table 1, 2, 3, Fig 1, the observations on postpartum reproductive performance are shown in Table 4 and the comparative economics of various supplements in Table 5.
Plasma insulin and insulin-like growth factor-1 (IGF-1)
The mean plasma insulin levels across the groups revealed significant (P<0.01) effect of treatments, the values being lower in all treatment groups than in control (Table 1, Fig 1). Moreover, the insulin levels were found to be reduced significantly (p<0.05) on day 15 postpartum, overall and in T1, T3 and T5 groups and non-significantly in T2 and T4 groups. It showed decline in all groups from day 30 prepartum to day of calving and then had rising trend till day 45/60 postpartum. Comparatively more decline in insulin levels observed in T3 and T4 groups than in T1, T2 and T5 groups might be due to beneficial effect of RPF supplement on this hormone. Overall plasma insulin levels were significantly higher in T1 and T5 groups as compared to others. Supplementation of both RPC and RPF alone or in combination reduced the plasma insulin concentration in periparturient Gir cows.
Garnsworthy et al., (2008) also reported significantly decreased plasma insulin concentration in dairy cows supplemented with bypass fat, while
Leiva et al., (2015) and
Acharya et al., (2019a) reported significantly higher blood insulin level in the dairy cows supplemented with RPC during peripartum periods. However, a non-significant effect on plasma insulin concentration with RPC supplementation
(Chung et al., 2009) in lactating Holstein cows and bypass fat or prill fat from 40 days prepartum till 90 days postpartum
(Tyagi et al., 2010; Singh et al., 2014) has been reported earlier.
Like insulin, the overall mean values of plasma IGF-1 were found to be significantly (p<0.001) lower in groups T3 and T4 and non-significantly lower in T2, as compared to T5 (Se + Vit-E) and T1 (control). The significant differences were also observed between peripartum periods in all groups (Table 1, Fig 1). Plasma IGF-1 levels were significantly (p<0.001) reduced on day 30
th postpartum overall and in all groups, except T3, as compared to values of prepartum and postpartum periods. Further, the IGF-1 levels declined gradually and significantly from day 30 prepartum till day 30 postpartum and then further rose till day 45/60 postpartum in all supplemented and control groups.
Acharya et al., (2019a) reported significantly higher plasma IGF-1 level in cows supplemented with RPC, while
Leiva et al., (2015) reported non-significant effect. We observed significant decrease in plasma IGF-1 level in the cows supplemented with RPF and RPF+RPC as compared to control or Se + Vit-E supplemented group. However,
Garnsworthy et al., (2008) did not observe significant effect of various levels of bypass fat on plasma IGF-1 concentration in lactating dairy cows.
Effect on plasma progesterone and estradiol profile
The mean plasma progesterone (P
4) concentrations were maximum on day 30 prepartum in all the groups, which declined significantly (p<0.01) by day 15 preparturm and then dropped abruptly to the basal levels (<1 ng/ml) on the day of parturition. Subsequently these values fluctuated non-significantly around the basal levels from day 15 with rising trend around day 45/60 postpartum (Table 2, Fig, 1), suggestive of presence of luteinized follicles or corpora lutea preceded by silent ovulations in some of the animals, particularly in groups T5, T4 and T3. The mean plasma estradiol-17β concentrations (E
2) recorded in cows of different groups at day 30 prepartum increased significantly or apparently at day 15 prepartum with highly significant rise (P<0.01) on the day of calving. Thereafter, there was a sudden and significant (p<0.01) drop in the mean plasma estradiol levels to the basal values by day 15 postpartum and then it fluctuated insignificantly between days 15 and 60 postpartum in all groups (Table 2). The basal value of progesterone found on the day of calving was suggestive of complete luteolysis at parturition and corroborated with the findings of
Dhami et al., (2017) and
Kalasariya et al., (2017). The overall trend of peripartum E2 profile found in animals under study coincided well with that reported by many of the earlier researchers in dairy animals
(Dugwekar et al., 2008; Dhami et al., 2017; Kalasariya et al., 2017).
The period wise or overall mean values of plasma P
4 however did not vary significantly between groups, though it was apparently much higher on day 60 postpartum in groups T5, T4 and T3. The E
2 levels varied significantly overall and at most peripartum intervals between groups, the values being lowest in T5 and higher in T3 and T4 (Table 2). Dietary supplementation of fat increases the circulating concentrations of cholesterol, which serves as a precursor for the synthesis of steroid hormones by ovarian theca and luteal cells and also increases the lifespan of induced CL
(Rahbar et al., 2014). Tyagi et al., (2010) and
Kalasariya et al., (2017) also found that the fatty acids and protein supplemented cows had non-significantly higher progesterone values as compared to control group. The observed higher level of plasma P
4 might be due to the substantial production by the functional CL. The prolonged period of inhibition during pregnancy from continuous negative-feedback effect of P
4 secreted by the CL and placenta causes the pituitary to become refractory to GnRH postpartum
(Lammoglia et al., 1997). This eventually recovers with time. As a result of the absence or low output of gonadotrophins in early postpartum phase the ovaries remain relatively quiescent and the cow shows anestrum. The trend of plasma P
4 concentration observed in peripartum periods of Gir cows corroborated well with the findings of
Chaiyabutr et al., (2000), Ishikawa et al., (2004) and
Dhami et al., (2017). The overall trend of E
2 profile found coincided well with observations of earlier researchers
(Kindahl et al., 2004; Shah et al., 2006, Kalasariya et al., 2017). It is fact that after parturition the levels of estradiol-17β markedly decrease and fluctuate at basal levels until the initiation of postpartum follicular activity in dairy bovines
(Dhami et al., 2017; Vala et al., 2019).
Effect on plasma PGFM and cortisol profile
The plasma concentration of PGFM (13, 14-dihydro, 15-keto-PGF
2α) was found to be lowest or basal on day 30 prepartum, which increased gradually and significantly (p<0.01) in all groups reaching peak values of 1.5-fold greater on the day of calving, which then further increased non-significantly by day 15 postpartum and then declined gradually and significantly till day 60 postpartum, attaining the basal values at par with those of 30 days prepartum. The rise was significantly (p<0.01) lower in nutrients supplemented groups T3, T4 and T5 than in treatment T2 and control group T1 (Table 3, Fig 1). In our earlier studies almost similar trend, but relatively much higher values (8-12 fold) of peripartum PGFM profile in bypass fat and minerals supplemented crossbred cows
(Dhami et al., 2017) and Jaffarabadi buffaloes
(Vala et al., 2019) were observed. The trend of PGFM recorded peripartum is a reflection of PGF
2α production around parturition for inducing luteolysis and for uterine involution. There is an intense production of PGF
2α by inter-caruncular region of endometrial epithelial surface during early puerperium, which correlates to uterine involution process
(Skarzynski et al., 2000; Dhami et al., 2017). High concentration of PGFM beyond day 20 postpartum may suggest the presence of uterine inflammation and/or infection and thereby delaying involution of uterus
(Kindahl et al., 2004). Archbald et al., (1998) opined that high plasma PGFM in cows between days 24 and 29 postpartum are indicative of uterine infection, that results in infertility. The PGFM in the early postpartum period was found (P=0.10) to be higher in cows fed fatty acids and affected the uterine health and reproductive efficiency through alteration of PGFM concentration
(Lammoglia et al., 1997; Rodriguez-Sallaberry et al., 2007). The present findings are in close agreement with earlier reports (
Sheldon and Dobson, 2000;
Heppelmann et al., 2013).
The mean plasma cortisol concentrations in cows of different groups varied non-significantly between 21.65±2.68 and 27.44±1.80 ng/ml at day 30 prepartum, which increased significantly or apparently by day 15 prepartum, but increased rapidly to nearly 1.5-fold (p<0.01) on the day of parturition reaching a peak, the rise was more in all treatment groups compared to control. Thereafter, the levels decreased significantly on day 15 postpartum and then fluctuated non-significantly (Table 3, Fig 1). The nutrients supplemented cows tended to have non-significantly (p<0.01) higher cortisol values than the control cows. Further, it was found that the occurrence of the postpartum estrus was earlier in cows of all the treatment groups than the control. Very similar trend but with relatively much lower values of peripartum cortisol profile in bypass fat supplemented cows
(Dang et al., 2013; Dhami et al., 2017) and comparable values in Jaffarabadi buffaloes
(Vala et al., 2019) have been reported earlier. It is suggested that cortisol may play a role in the CL as an anti-apoptotic factor in the bovine luteal cells
(Rueda et al., 2000) and that the CLs have the potential to respond to a locally generated cortisol
(Michael et al., 2003). The observed levels and trend of changes in cortisol values were found to be similar to the findings of
Chaiyabutr et al., (2000), who reported that the cortisol levels in the prepartum days were initially low, but increased as parturition approached.
Effect on postpartum fertility
Uterine involution observed by ultrasonography was found to be earlier in all supplemented groups over control with or without significant differences. Moreover in all the nutrients supplemented groups of Gir cows, the commencement of cyclicity was significantly earlier (p<0.001) as compared to control (Table 4) and the values of T2, T3 and T4 groups were found to be statistically similar with either T1 or T5. A positive effect of supplementation of bypass fat and choline
(McNamara et al., 2003; Tyagi et al., 2010; Khalil et al., 2012) and of Vit E and Se
(Mavi et al., 2006; Jovanovic et al., 2015; Hosnedlova et al., 2017) on uterine involution and occurrence of first estrus postpartum with improved conception rate, as observed in present study, has also been reported by earlier researchers. Onset of postpartum cyclicity is related with the process of involution and health of the uterus. Uterine involution was reported to be enhanced significantly by
Pirestani and Aghakhani (2018) and non-significantly by
Acharya et al., (2019b) in cows fed with RPC. Further, in contrast to present findings, supplementation of RPC during peripartum period did not influence cyclicity in earlier studies
(Amrutkar et al., 2015; Anonymous, 2020). The significant effect of RPF supplementation peripartum on commencement of cylicity observed in present study was in agreement with findings of
Dhami et al., (2017) and Vala
et al., (2019), who observed significantly reduced time for commencement of cyclicity in peripartum RPF supplemented crossbred cows and Jaffarabadi buffaloes as compared to control. In contrast,
Nirwan et al., (2019) observed non-significant difference for this trait in peripartum RPF supplemented cows.
Service period was significantly shortened with numerically reduced number of services per conception (Table 4) in T5 group supplemented with Se + Vit-E than that of control and the values for RPC, RPF and its combined supplementation were statistically similar with either T1 or T5 group, suggesting beneficial effect of all four supplementation tested in transition cows and T5 in particular. Our results were in agreement with
Tyagi et al., (2010), who reported shorter service period in bypass fat supplemented groups of cows than in control and
Pirestani and Aghakhani (2018) observed improvement in service period with reduced AI per conception in the cows receiving RPC in peripartum periods. However,
Khalil et al., (2012) did not find such effect of nutrient supplements on service period, although the conception rate was improved. In some other studies, the service period and AI/conception were reported to be improved significantly in dairy cows and buffaloes due to supplementation of RPC or protein
(Amrutkar et al., 2015; Acharya et al., 2019b; Anonymous, 2020) and RPF
(Dhami et al., 2017; Nirwan et al., 2019; Vala et al., 2019) during peripartum period. Fats and choline in the diet influence reproduction positively by altering both ovarian follicle and CL function via improved energy status and by increasing precursors insulin and IGF-I for the synthesis of reproductive hormones such as steroids and prostaglandins. The increase in insulin plays a role in mediating increased follicular growth, either directly through its own receptor or indirectly by modulating granulosa cell IGF-I production which is required for follicle development
(Rahbar et al., 2014; Anonymous, 2020).
In the present study, postpartum fertility was better with Vit-E and Selenium injections than with RPC and RPF supplementation in diet, perhaps due to their potent antioxidant potential alleviating oxidative stress and thereby better feed intake preventing NEB. In earlier studies also, Vit-E and Selenium injections or oral supplements in diet prepartum and/or peripartum have been reported to reduce significantly the oxidative stress
(Dimri et al., 2010; Modi et al., 2016; Khatti et al., 2017), incidence of retained placenta
(Arechiga et al., 1994; Gupta et al., 2005; Moeini et al., 2009; Damarany, 2021) and to improve postpartum reproductive performance
(Sattar et al., 2007; Dimri et al., 2010; Qureshi et al., 2010; Pontes et al., 2015; Khatti et al., 2017) in dairy cows and buffaloes.
Economics of peripartum supplementation in Gir cows
Average daily cost of feeding (Rs./head) for T1, T2, T3 T4 and T5 group was calculated to be 194.80, 228.15, 210.59, 214.96 and 186.87, respectively. The corresponding net return over feed cost of milk yield (Rs./head) was 4428.00, 5326.50, 6486.90, 6333.60 and 5502.00, respectively and that due to reduced service period over control T1 was +14999.60, +4090.80, +5259.60 and +22986.40 for T2, T3 T4 and T5, respectively. The overall net returns over feed cost of milk yield and reduced service period (Rs./head) in T2, T3, T4 and T5 groups over control T1 were +15898.10, +6149.70, +7165.20 and +24060.40, respectively, indicating that it was highest in T5 followed by T2 and in T3 group (Table 5). The data proved that both production and reproduction efficiencies and thereby economic of Gir cows supplemented with Se+Vit-E, followed by RPC and RPF alone for 90 days peripartum were markedly improved. Very similar economic benefits of these supplementations either during peripartum or postpartum period in dairy cows have been reported by several earlier researchers
(Mohsen et al., 2011; Singh et al., 2014; Sankhpal et al., 2016, Anonymous, 2020) from different parts of country. Hence farmers should be advised to incorporate Se+Vit-E, followed by RPC and RPF alone as per economic merit in dairy animals for harvesting its benefits.
