IMPROVEMENT OF THE REPRODUCTIVE PERFORMANCE OF EGYPTIAN BUFFALO COWS THROUGH DIFFERENT MANAGEMENT SYSTEMS

 

E. B. ABDALLA

 

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

 

 

ABSTRACT

The objective of the present study was to determine the possibility to improve the reproductive performance of buffalo cows through the continuous exposure to bull with grazing and free-stall housing management. Sixty-four Egyptian multiparous buffalo cows raised under two different management systems in two farms were used in this study. 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). In each farm, cows were visually checked twice daily for the signs of oestrus and animals proved standing heat were naturally  mated. The post-partum ovarian activity was monitored by rectal palpation of ovarian structures in addition to the determination of serum progesterone concentration of blood samples collected two times per week.

The results revealed that post-partum intervals to each of 1st ovulation, 1st oestrus, conception and next parturition were significantly (P<0.05) shorter in MS1 group than in MS2 group. In the meantime, MS1 increased (P<0.01) the conception and calving rates by 21 and 25 %, respectively compared to MS2. Percentages of post-partum cyclic animals and animals exhibiting ovulatory oestrus were greater (P<0.01) in  MS1 group than in  MS2 group. However, the percentage of animals cycling before day 60 post-partum was significantly (P<0.01) lower in MS1 group than in  MS2 group (13 vs 28%). By day 120 post-partum, only 63% of the buffaloes were cycling in MS2 group versus 94% in  MS1 group.

Percentage of silent ovulation was insignificantly higher in MS2 group (34%) than in MS1 group (25%). However, the percentage of false oestrus was higher ((P<0.01) in MS1 group than in MS2 group (16 vs 3%). In addition, percentage of short ovulatory cycles (15 to 17 days) was greater (P<0.01) in MS1 group than in MS2 group, whereas percentage of long ovulatory cycle (25 to 28 days) was higher (P<0.01) in MS2 group than in MS1 group. It was concluded that continuous exposure of buffalo cows to a fertile bull with grazing management under free-stall housing system enhances resumption of post-partum ovarian activity and improves conception and calving rates, especially in the medium and large scale herds.

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

 

INTRODUCTION

            Efficiency of reproduction is one of the most critical aspects of a profitable herd. To maximize her productive life, a buffalo cow must be bred within 80 to 90 days after parturition to produce a new calf and starts a new lactation every 13.0 to 13.5 months. Longer calving intervals in Egyptian buffaloes are mainly due to extended days open following parturition (El-Fouly et al., 1976), which can be attributed to irregular ovarian activity, weak expression of oestrus and poor oestrus detection (Khattab et al., 1990).

            In order to detect more than 90% of the incidence of oestrus in a herd, cows should be observed carefully in the early hours of the morning, the late hours of the evening and at 4 to 5 hour intervals during the day (Wattiaux,1995). However, this frequency of heat detection involves more labour and increases   production costs (El-Wardani and Asheeri, 2000). The presence of a bull is recommended to improve heat detection and increase pregnancy rate (Zicarelli et al., 1991). Moreover, heat detection may be facilitated by housing or yarding cows in groups to increase the chance of sexually active group formation and makes heat detection much easier (Wattiaux, 1995).

            Enhancing the post-partum resumption of ovarian activity to shorten calving interval has been achieved by hormonal treatment (Aboul - Ela et al., 1985), introducing the male (Fike et al., 1996) or nutritional treatment (Abdalla, 1996). Suckling is an exteroceptive stimulus that plays a major role in governing reproductive cycles in female mammals (McNeilly, 1988). Little is known concerning the effect of different management practices on the reproductive performance of females. Therefore, the objective of this experiment was to study the influence of the presence of a fertile bull, housing system, allowance of grazing and length of suckling period on the post-partum ovarian activity in Egyptian buffalo cows.

 

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 2nd and the 6th 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 with allowance of four hours grazing per day (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 and the oestrous cows were naturally mated. Rectal palpation was performed once a week up to mating to determine the time of post-partum uterine involution, and 45 days after mating to diagnose pregnancy. Animals diagnosed non-pregnant were observed for oestrus and re-mated on the next standing oestrus. Blood was sampled twice per week via  jugular venipuncture starting from seven days post-partum and continued up to about 150 post-partum. The serum was harvested and stored at -20C 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.

The serum progesterone concentration was used to monitor ovarian function during the first 150 days post-partum. The resumption of ovarian cyclicity was evaluated as the time from parturition to the first increase in serum progesterone concentration above 1.0 ng/ml (Barkawi, 1993). A rise in serum progesterone concentration (1.0 ng/ml) for at least two consecutive samples was considered to be a reliable index of the resumption of ovarian activity (luteinization). Silent ovulations, false oestrus and non-cyclic animals were identified from serum progesterone levels and behavioural observations. Ovulatory cycles were grouped into short (15 to 17 days), normal (18 to 24 days), long (25 to 28 days) and abnormal long  ( 29 days) cycles. Statistical analyses were performed using t - test to compare the MS1 and MS2 means, while numerical values were compared using the Chi-square test (SAS, 1990). 

 

RESULTS

            The interval from calving to uterine involution was similar for both groups of buffalo cows. However, the management system in the first farm (MS1) reduced (P<0.05) the interval from calving to 1st ovulation (29 vs 43 days), 1st oestrus (39 vs 59 days), conception (85 vs 121 days) and next parturition (420 vs 484 days) as compared to the management system in the second farm (MS2) (Table 1). Moreover, the percentage of post-partum cyclic animals and animals which resumed ovarian cyclicity with expression of oestrus was greater (P<0.01) in the MS1 group than in the MS2 group (Table 2). The percentage of silent ovulations tended to be higher in the MS2 group than in the MS1 group, but the difference was not significant. Table 2 also indicated that the incidence of false oestrus was higher (P<0.01) in the MS1 group than in the MS2 group, although MS1 animals had greater (P<0.01) conception and calving rates than those in the MS2 group (84 vs 63 and 75 vs 50 %, respectively).

The proportion of animals resuming ovarian activity before day 60 post-partum was significantly (P<0.01) lower in the MS1 group than in the MS2 group (13 vs 28) (Table 2). By day 120 post-partum, 94% of the animals in the MS1 group had shown ovarian cyclicity compared with 63% of the animals in the MS2 group. Moreover, 81% of the animals in the MS2 group resumed ovarian activity by day 150 post-partum. The post-partum ovulatory cycle length ranged from 15 to 55 days and its  frequency distribution is shown in Fig. 1. The incidence of short cycles was greater (P<0.01) in the MS1 group and that of long cycles was higher (P<0.01) in the MS2 group. The proportion of normal cycles was similar for both groups of baffaloes. Although more MS2 animals had abnormally long cycles than MS1 animals, this difference was not significant.

 

Table (1): Effect of two different management systems (MS1, MS2) on some reproductive criteria (mean SE) in Egyptian buffalo cows

Reproductive criteria

MS1 (n= 32)

MS2 (n= 32)

Significance

Post-partum interval (d) to:

        1st ovulation

 

29.21.2

 

42.72.0

 

P<0.05

        1st oestrus

38.71.0

58.53.3

P<0.05

        uterine involution 

28.10.5

29.40.7

NS

        conception

84.51.7

120.82.8

P<0.05

Calving interval (d)

4204.6

4844.7

P<0.05

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.

Table (2): Some post-partum reproductive criteria of Egyptian buffalo cows raised under two management systems (MS1, MS2) during the first 150-day period

 

Reproductive criteria

MS1

MS2

Significance

No.

%

No.

%

Total number of animals

32

-

32

-

 

Noncyclic animals

2

6

6

19

P<0.01

Animals cyclic within:

 

 

 

 

 

day 0 60

4

13

9

28

P<0.01

day 60 - 90

24

75

6

19

P<0.01

day 90 120

2

6

5

16

P<0.01

day 120 150

-

-

6

19

-

day 0 90

28

88

15

47

P<0.01

day 0 120

30

94

20

63

P<0.01

day 0 150

30

94

26

81

P<0.01

Ovulatory oestrus

22

69

15

47

P<0.01

Silent ovulation

8

25

11

34

NS

False oestrus

5

16

1

3

P<0.01

Animals conceived

27

84

20

63

P<0.01

Animals calved

24

75

16

50

P<0.01

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.

Fig.1. Percentage distribution of post-partum ovulatory cycle length 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.

Figures in parenthesis represent number of cycles.

*Difference between MS1 and MS2 was significant (P<0.01). 

DISCUSSION

            The post-partum intervals to either 1st ovulation or 1st oestrus were shorter in MS1 than in MS2 buffalo cows. In agreement with the present results, Hurnik and King (1975) reported that the post-partum interval to 1st oestrus was 34.5 days for free-stall and 56.6 days for tie-stall cows. However, longer intervals were reported by Abdou (2001) for Egyptian buffalo cows raised under tie-stall housing system with twice daily exposure to bull. The present results clearly indicate that continuous exposure to bull, free-stall housing and grazing management for four hours daily accelerates the resumption of ovarian activity. Mohamed et al. (1980) reduced post-partum to 1st ovulation interval (49 days) in Egyptian buffalo cows by improving nutrition and management. Several investigators have reported that body condition score at and after calving (Wright et al., 1982), suckling (El-Fouly et al., 1976), season (Raza et al., 2001) and bull-cow interactions (Custer et al., 1990) are important factors influencing resumption of post-partum ovarian activity. Consequently, the combination of male presence, group housing with free-stall, addional  grazing and careful  oestrous detection combined with balanced nutrition probably account for the earlier post-partum resumption of ovarian activity observed in MS1 in this study.

            El-Wardani et al. (1998), however, reported that exposing buffalo cows to the male twice daily resulted in a reproductive performance better  than that for animals exposed continuously to the male. The reason for this conflict is unclear, but it could be suggested that the male effect on reproductive performance of buffaloes may be confounded with the management regime. Moreover, Aboul-Ela (1993) showed that reproductive performance of buffaloes raised on small holdings was better than that of buffaloes raised under conditions of  large scale experimental farms where the animals received less attention and heat detection was less accurate. Thus, the continuous exposure of cows to a fertile bull, as in the present study, is likely to detect most oestrous cows, especially when the cows are loose housed.

The present results indicate that about 88 and 47% of buffaloes have resumed ovulatory activity by 3 months and these values amounted to 94 and 63% by 4 months post-partum in the MS1 and MS2 groups, respectively. These findings are in agreement with those of Khattab et al. (1990) and Barkawi (1993) who indicated that physiological disorders do not appear to be the main reason for the post-partum reproductive disorders. However, the incidence of silent ovulations which represented 25 and 34% in the MS1 and MS2 groups, respectively, may be an important reason for the post-partum reproductive failure in buffalo cows. The presence of bull and free-stall group housing practiced in the present study (MS1) reduced the incidence of silent ovulation, resulting in higher conception rate and shorter days open and calving interval as compared with the restricted bull exposure and the tie-stall housing management system (MS2). Several investigations have shown that the incidence of oestrus in Egyptian buffaloes is highest around sunset and sunrise (Barkawi et al., 1997; El-Wardani and Asheeri, 2000) and this needs more intensive observation or continuous presence of bull to detect oestrous behaviour. The higher incidence of false oestrus in the MS1 group may be due to the male pheromone effect on the female's central nervous system (Aron, 1979). This may be also the reason of the increased percentage of short ovulatory cycles (15 to 17 days) observed in this group.

It is worthy to note that more buffaloes in the MS2 group (28 %) resumed ovarian activity within 60 days post-partum than in the MS1 group (13%). However, during the third month post-partum more MS1 animals resumed ovarian activity than in the MS2 group (75 vs 19 %). It should be noted that the suckling period lasted only one week for MS2 cows, but it continued for 2 to 3 months for MS1 cows. Suckling is known to delay the resumption of post-partum ovarian activity while restricted suckling and early weaning enhance post-partum ovarian cyclicity (Radford et al., 1978; Wettemann et al., 1978). Barkawi (1993) found that 40% of suckled buffalo cows showed sustained anoestrus during the first 90 days post-partum, as compared with only 10% of milked cows. A similar effect was observed during the first 60 days post-partum in the present experiment. Thereafter, the calves became less dependent on suckling and the adverse effect of suckling diminished while other managerial factors became more effective. Thus, it is interesting to note that good managerial practices (e.g. MS1) may alleviate the adverse effect of suckling on the post-partum reproductive performance of buffaloes and this was observed after 2 months post-partum.

 

CONCLUSION

This study showed that silent ovulation is a common problem in buffalo cows even under good management (MS1). The continuous male-female interaction (through olfactory, visual, acoustic, tactile  and pheromones) had a beneficial effect on the onset of post-partum cyclicity in buffaloes. Incorporation of continuous male presence into free-stall housing and additional grazing may optimize the overall reproductive performance of post-partum Egyptian buffalo cows. The present study confirmed that suckling has less powerful effect on the inhibition of ovarian activity in buffaloes when a good management is practiced. Moreover, the type of housing (free or tie) should be taken into consideration when studying reproductive performance especially in buffalo cows. Herds housed in a tie-stall barn should have an exercise area where cows can associate freely with a bull for a few hours early and late in the day.


 

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