PROGESTERONE PROFILE IN CYCLIC AND PREGNANT EGYPTIAN BUFFALO COWS RAISED UNDER TWO DIFFERENT MANAGEMENT SYSTEMS

 

E.B. ABDALLA

 

Department of Animal Production, Faculty of Agriculture, Ain Shams University, Shobra El-Kheima 11241, Cairo, Egypt

 

ABSTRACT

Sixty-four Egyptian multiparous buffalo cows were raised under two different management systems in two farms to study the effects of male, grazing, housing system and length of suckling period on the pattern of progesterone concentration changes during ovulatory cycle and pregnancy. The cows in the first farm (management system 1, MS1) were loose-housed in a free-stall yard, grazed for 4 hours per day, suckled their calves for 2 to 3 months and were continuously exposed to a fertile bull. The cows in the second farm (management system 2, MS2) were confined in an open-fronted tie-stall shed, not grazed, suckled their calves for only 7 days and were exposed to a fertile bull twice per day (30 min/session). Blood samples were collected twice weekly during ovulatory cycles and at monthly intervals during pregnancy for serum progesterone determination.

   The results revealed that management systems (MS1& MS2) significantly affected overall mean progesterone concentration in long ovulatory cycle, where  higher (P<0.01) levels were obtained under MS2. In normal cycle, progesterone levels elevated with progressing days of the cycle under both MS1 and MS2, being significantly (P<0.01) at minimum on day of oestrus. Progesterone level was higher during days 5-16 of normal cycle under MS1 compared to MS2. The opposite trend was observed during the subsequent days from 17 to 24 of the cycle. In both groups, progesterone concentration reached its peak between days 13-16 of the cycle and tended to decrease thereafter.

During the first two months of pregnancy, animals raised under MS1 had progesterone concentrations higher (P<0.01) than those under MS2. While starting from the 4^th up to the 8^th month of pregnancy, higher (P<0.01) progesterone levels were recorded under MS2 comparing with the corresponding MS1 values. Corpus luteum seemed to be more active during early pregnancy under MS1, and during the subsequent durations of pregnancy in the MS2 group. It was concluded that decreased level of progesterone on day of oestrus and its increased level during early pregnancy detected in MS1 buffaloes may reflect favourable reproductive performance. The physiological mechanism concerning these respects remains unclear and needs further investigations.

Keywords: Buffalo; Progesterone; Housing; Suckling period; Nutrition; Male presence

 

INTRODUCTION

            Progesterone is a steroid hormone with key functions in regulation of female reproduction. Its levels either in blood or in milk provide an early marker for determining the functional status of the post-partum ovarian activity (Chandra et al., 1993; Zeitoun and Fathelbab, 1994; Tiwari et al., 1995; Abdalla, 1996; Pandit and Chauhan, 1998; Abdalla, 2002). In the meantime, Usmani et al. (1985) reported that using ovarian palpation alone may not necessarily show a true picture of the ovarian activity, since there was a risk due to frequent presence of embedded corpora lutea (El-Wishy, 1979; Younis et al., 1994), particularly during the early post-partum period in buffalo cows.

            Moreover, blood progesterone level could be used for pregnancy diagnosis as well as in the detection of silent and anovulatory heat (Kamonpatana et al., 1981; Sharma and Kaker, 1990; Raggi et al., 1999). However, progesterone concentration may be affected by season (Rao and Pandey, 1982; Qureshi et al., 1999), presence of bull (Mohamed, 2001), level of nutrition (Vale et al., 1990), suckling (Nordin and Jainudeen, 1991; Hussein, 2000) and hormonal treatment (Hattab and Zeitoun, 1999). The effect of management system, including housing system, allowance of grazing,  presence of bull and length of suckling period, on the blood progesterone profile in buffalo cows has not been fully investigated. Therefore, the aim of the present study was to investigate the influence of different management systems usually applied in the animal farms on the blood progesterone profile in buffalo cows during ovulatory cycle and pregnancy.

 

MATERIALS AND METHODS

            Sixty-four multiparous Egyptian buffalo cows, calved during early December and early January and raised at two experimental farms located in the same area and belonging to Faculty of Agriculture - Ain Shams University, were used in this study. All buffaloes were between the 2^nd and the 6^th parity, weighing 450 to 480 kg and free from reproductive disorders. Average daily milk yield ranged from 5.0 to 6.5 kg per head. The animals in the first farm (n=32) were kept in a group with access to free stalls in semi-open sheds. They were allowed for grazing four hours daily (from 0800 to 1200 h). A mature fertile bull was continuously running with the cows. The cows were also allowed to nurse their calves for 2 to 3 months after calving and thereafter they were milked twice daily at 0600 and 1500 h.  In the meantime, animals in the second farm (n=32) were kept in tie stalls in semi-open sheds without access to grazing. The cows were exposed twice daily to a mature fertile bull (30 min/ session) at 0700 and 1700 h. These cows were allowed to nurse their calves for seven days post-calving, then milked twice daily as in the first farm.

Animals in both farms were fed a concentrate mixture, green berseem (Trifolium alexandrinum) and rice straw according to their maintenance and production requirements (El-Ashry, 1980). Animals were checked visually for signs of oestrus twice daily (30 min / session) at 0700 and 1700 h. Blood was sampled twice per week via jugular venipuncture starting from 45 days post-partum and continued up to mating, then at monthly intervals throughout the entire pregnancy period. Rectal palpation was performed after 45 days of mating to diagnose pregnancy. Animals diagnosed non-pregnant were observed for oestrus and re-mated on the next standing oestrus. The blood serum was harvested and stored at -20 °C until assayed for progesterone using a commercially available radioimmunoassay (RIA) kit (Immunotech, A Beckman Coulter Company, France). The sensitivity of the assay was about 0.3 ng/ml, while the intra- and inter-assay coefficients of variation were 8.5% and 13.7%, respectively. Ovulatory cycles were grouped into short (15 to 17 days), normal (18 to 24 days) and long (25 to 28 days) cycles. Statistical analyses were performed using  t - test ( SAS, 1990) to test the significance of differences among the obtained results.

 

RESULTS

1.Serum progesterone (P₄) profile during ovulatory cycle:

            As shown in Table 1, overall mean concentration of serum P₄ in the short (15 to 17 days), normal (18 to 24 days) and long (25 to 28 days) ovulatory cycles was 1.74, 1.88 and 1.74 ng/ml for MS1 group versus 1.70, 1.86 and 2.04 ng/ml for MS2 group, respectively. In the short cycle, the highest P₄ level was detected between 5-8 days for MS1 group and 9-12 days for MS2 group. Progesterone mean concentration in the short cycle did not significantly differ between MS1 and MS2 groups, except at durations 5-8 and 9-12 days, at which peak values were significantly (P<0.01) different between the two groups. In the normal and long ovulatory cycles, P₄ level showed peak values at duration 13-16 days in both MS1 and MS2 groups. In the normal cycle, P₄ mean values were significantly (P<0.01) higher in MS1 than in MS2 group at intervals 5-8 and 9-12 days, with an opposite trend at intervals 17-20 and 21-24 days of the cycle. In the long cycle, P₄ mean values were higher in MS2 than in MS1 allover the cycle, but being significant (P<0.01) at intervals 17-20 and 21-24 days.

Table (1): Mean (±SE) of serum progesterone concentrations (ng/ml) during the short, normal and long ovulatory cycles of Egyptian buffalo cows raised under two management systems (MS1 & MS2)

Days of		Short cycle (15-17 d)				Normal cycle (18-24 d)			Long cycle (25-28 d)
	Cycle		MS1	MS2	MS1		MS2	MS1		MS2
	1-4		1.08±0.18	0.97±0.12	0.86±0.13		0.71±0.14	0.43±0.11		0.56±0.10
	5-8		3.62±0.31	2.91±0.34*	1.96±0.23		1.17±0.21*	1.32±0.24		1.45±0.21
	9-12		2.84±0.37	3.35±0.32*	2.78±0.39		2.12±0.31*	2.18±0.31		2.19±0.28
	13-16		1.03±0.25	1.12±0.14	3.61±0.31		3.30±0.27	3.70±0.34		3.86±0.31
	17-20		0.15±0.03	0.16±0.04	1.82±0.30		2.98±0.33*	2.52±0.28		3.01±0.40*
	21-24				0.23±0.05		0.88±0.16*	1.73±0.26		2.82±0.25*
	25-28							0.29±0.11		0.42±0.14
	Overall mean		1.74±0.64	1.70±0.61	1.88±0.50		1.86±0.45	1.74±0.45		2.04±0.49*

MS1 = Full-time exposure to bull, free-stall housing, grazing was practiced for 4 hours daily and natural suckling was allowed for 2 to 3 months post-partum.

MS2 = Twice daily exposure to bull, tie-stall housing, no grazing allowed and natural suckling was allowed for only 7 days post-partum.

*Difference between MS1 and MS2 was significant (P<0.01) at each particular duration of the cycle.

 

            Serum P₄ profile detected during normal ovulatory cycle in the two groups revealed that there was a gradual increase from the basal level till the peak value during durations 13-16 days (3.65 ng/ml) and 17-20 days (3.01 ng/ml) for MS1 and MS2 groups, respectively, then followed by a gradual decrease reaching the basal value at the end of cycle (21-24 days) as shown in Table 2 and Fig. 1. The basal level of P₄ on day of mating (day 0) was significantly (P<0.01) higher in MS2 than in MS1 group, while at intervals 5-8, 9-12 and 13-16 days the P₄ level in MS1 group was significantly (P<0.01) higher than that in MS2 group. At subsequent durations (17-20 and 21-24 days) the P₄ level was higher (P<0.01) in MS2 than in MS1 group. It is worthy to note that serum P₄ concentration after reaching its peak value, started to decrease sharply and earlier in MS1 group than in MS2 group to reach a basal level, which was significantly (P<0.01) lower in MS1 than in MS2 group.

 

 

 

 

Table 2

 

 

 

Fig.1. Changes in serum progesterone concentration during the normal

          ovulatory  cycle  of  Egyptian  buffalo  cows  raised  under  two

          management systems (MS1 & MS2).

MS1 = Full-time exposure to bull, free-stall housing, grazing was practiced for 4 hours daily and natural suckling was allowed for 2 to 3 months post-partum.

MS2 = Twice daily exposure to bull, tie-stall housing, no grazing allowed and natural

             suckling was allowed for only 7 days post-partum.

    0   = Day of oestrus.

* Difference between MS1 and MS2 was significant (P<0.01) at each particular  duration of  cycle.

 

2. Serum P₄ profile during pregnancy:

            Figure 2 showed that there was a sharp increase in serum P₄ level during the 1^st month of pregnancy, which was more pronounced in MS1 than in MS2 group. Progesterone level continued to increase but at a lower rate till the 2^nd month in MS1 and the 4^th month in MS2. Then P₄ level was maintained with few changes till  the 10^th month of pregnancy in both groups. Commencing from the 10^th month of pregnancy, P₄ level in the two groups sharply decreased to reach the basal level around the time of parturition. Mean P₄ concentration was higher (P<0.01) in MS2 group than in MS1 group at day 0 (mating day) and at 4-8 months of pregnancy, while it was higher (P<0.01) in MS1 than in MS2 group at the 1^st and the 2^nd month of pregnancy.

 

 

 

 

Fig. 2.

 

 

 

 

 

DISCUSSION

            Studies dealing with the effect of management system on the pattern of progesterone concentration change during ovulatory cycle and pregnancy in buffaloes seem to be rare. The management systems practiced in this study affected the progesterone concentrations of the long cycle which were higher in animals raised under MS2 than in those raised under MS1. It seems that the presence of  bull with free-stalls and grazing management (MS1) declined the progesterone concentration, particularly in the long ovulatory cycle. On the other hand, the progesterone concentration of the short cycle started to decrease earlier in the MS1 group compared to that in the MS2 group. This decrease in progesterone levels was sharper in the normal and long cycles in MS1 than in MS2 group. Similar findings were obtained by Mohamed (2001), who revealed that progesterone concentration in the buffalo cows significantly (P<0.01) decreased in the presence of bull, which also resulted in shorter ovulatory cycle (Hornbukle et al., 1995).

            It is of interest to note the pattern of change in progesterone concentration during the days of normal ovulatory cycle under MS1 and MS2. Progesterone level was higher in MS2 than in MS1 at day 0 (basal level) of the cycle, then the opposite trend was observed between day 1 and up to day 16. The increased progesterone levels detected between days 1 and 16 of the cycle in the MS1 group could be attributed to the suckling effect and/or the presence of bull. Again, progesterone level was higher in MS2 than in MS1 during day 17 and up to day 24 of the cycle. It is obvious that progesterone level was relatively higher at day 0 of the cycle (0.79 ng/ml) and at the end of the cycle (0.82 ng/ml) under MS2 compared to that of 0.18 and 0.16 ng/ml in MS1, respectively. The elevated progesterone levels detected in buffaloes raised under MS2 on the day of oestrus (day 0)  may be due to incomplete regression of the corpus luteum (Singh et al., 1982). In addition, Usmani et al. (1985) reported a high concentration of progesterone (>1.5 ng/ml) on the day of standing oestrus in 23% of the buffaloes studied. This finding may explain the frequent incidence of silent ovulation or suboestrus in the buffalo cows.  Srivastava and Sahni (1999) reported that at the time of insemination, cows exceeding 0.50 ng/ml and buffaloes exceeding 0.90 ng/ml of blood progesterone concentration did not become pregnant. This finding could be confirmed by the previous investigation of Abdalla (2002) on the same animal groups. He stated that conception rate was significantly (P<0.01) lower in MS2 than in MS1 group (63 vs 84%).

Although the progesterone concentration was mostly similar in MS1 and MS2 groups throughout the entire period of pregnancy, it was relatively higher during the first two months in the MS1 group than in MS2 group. The opposite trend was observed starting from the 3^rd month of pregnancy up to parturition. Al-Gubory (1998) concluded that the stimulation of follicular growth and consequently estrogen secretion in the ewes continuously exposed to rams during early pregnancy may disrupt implantation and thereby lead to a greater embryonic losses. In the present study, however, continuous exposure of buffalo cows to bull (MS1 group) combined with grazing resulted in higher levels of blood progesterone during early pregnancy compared to that of MS2 group. Elevated progesterone levels during early pregnancy improved calving rate in MS1 group (Abdalla, 2002), probably as a consequence of the decreased early embryonic mortality. Anyhow, regulation of progesterone secretion is not well understood but is considered to be primarily stimulated by LH in domestic animals (Reeves, 1987).

 

CONCLUSION

This study showed that measurement of progesterone levels is still the most reliable method to detect oestrus, ovulation and the ovarian function in the post-partum buffalo cows. Moreover, the present study confirmed that the progesterone levels detected on day of oestrus might help to explain some of the female reproductive disorders. Good management system (MS1) applied in this experiment clearly affects the progesterone concentration during ovulatory cycle and pregnancy and accelerates corpus luteum regression during ovulatory cycle. Good management may improve the reproductive performance of buffalo cows, probably through modifying the blood progesterone levels on day of oestrus and during early pregnancy.

 

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