Production Characteristics of Nili-Ravi Buffaloes

: Production and reproduction data of 47 Nili-Ravi buffaloes (162 records) were analyzed with regression techniques. Average lactation milk yield was 2,020.04 ± 44.59 liters, lactation length 277.42 ± 5.70 d and calving interval 467.10 ± 11.58 d. The ranges for these parameters respectively were : 609-3591 lit, 122-614 d and 228-982 d. Year of calving and lactation length had significant effect on total milk yield (p < 0.01), whereas other factors such as month of calving, lactation number and calving interval had no effect on total lactation milk yield. Year of calving had influenced significantly other traits (p < .01) such as calving interval and lactations completed. This indicated considerable environment role in buffalo productivity. Effect of month of calving on total lactation milk yield and other traits was however, found to be non-significant. Nili-Ravi buffaloes produced maximum milk during their first three lactations as compared to subsequent lactations. Regression model explained 40 percent variation in total lactation milk yield due to factors analyzed : animal (dam), year and month of calving, lactation length and calving interval.


INTRODUCTION
The buffaloes hold strategic place in the overall livestock economy of Pakistan and serve three impotant purposes viz, milk production, meat and drought power (Ghaffar et aL, 1991). Nili-Ravi buffaloes were of riverain type and have their home tract in the canal irrigated areas of central Punjab (Shah, 1991), Reproductive efficiency of dairy animals is the output of the interactions among environmental conditions, physiology of the animal and managemental factors such as estrus detection, natural mating procedures or inseminating techniques, fertility of the bull or the semen and herd health policies (Shah et aL, 1989).
Many workers have reported environment effects on milk yield and other production and reproduction traits in "Nili-Ravi buffaloes under different conditions. The information on these buffaloes under Barani (arid) Pothohar region are scanty. This study was, therefore designed to explore the magnitude of environment effects, such as year of calving and month of calving on different traits of economic importance in Nili-Ravi buffaloes. The climatic conditions of the centre, where these buffaloes were maintained, are quite different to their home tract, in central Punjab. There is shortage of green fodder during November-December and May-June. Average monthly rain fall of Islamabad is 200 mm in summer and 44 mm in winter. The winter is cold (minimum temperature range: -3 to +5 C).

The management practices included:
i) Buffaloes were bred through artificial insemination technique.
ii) The calves were weaned at 180 d. iii) Buffaloes were fed seasonal green fodder mainly berseem, maize and oats supplemented with concentrate ration @ 5 kg/head/day. iv) Buffaloes were grazed twice a day for about fourfive hours.
v) The calves suckled the dam before hand milking to stim니ate let down of milk.
Data were analyzed using "MSTAT" programmes for AJAS 1999 Vol. 12 (No. 1) 56-60 general linear models. The analyses of variation were conducted to observe the effect of different sources of variation on TMY and among each other. Multiple regression and correlation analyses were also conducted to quantify the effect of different variations among each others.

RESULTS AND DISCUSSION
The means (± residual standard deviation) for total lactation milk yield (TMY), lactation length (LL) and calving interval (CI) are given in table 1. These parameters respectively were: 2,020.04 ± 44.59 lit, 277.42 ±5.70 d and 467.98 ±11.58 d. The coefficient of variations for these traits ranged from 18 to 28 percent Table 2 presents proportion of the total variation in TMY, LL and CI accounted fbr by year of calving (YR), month of calving (MC) and lactation number (LN)-The analyses indicated that LL had highly significantly influenced TMY 근nd CI. These factor were positively correlated as well. YC had significant influence on TMY, CI and LL. This could be due to change in management and non-availabil时 of green fodder in required quantity in later years. In 1994 the area was hit by severe drought. Bugetory constraints hampered green fodder cultivation upto the required quantity. This probably played major role in significantly affecting TMY from 1986 to 1994.
Other workers have reported average lactation milk yield to be 1,641.10 ± 32.1 kg in Nili-Ravi buffaloes, in India (Bhaluri and Dhillon, 1987), and 1,916.99 ± kg in China (Huang and Wu, 1987). Table 2 and figure 1 presents the effect of YC on various traits. Year of calving (YC) had a significant effect (p < 0.05) on TMY. The proportion of variation accounted fbr by YC was found to be 27.33 percent. This trait had significantly (p < 0.001) affected other parameters such as CI and LN in the buffaloes. The YC effect may be attributed to many factors playing their role in buffalo productivity. Some of these fectors were: Weather conditions, availability of green fodder, animal and plant diseases, rainfall and management practices.

Year of calving
Other workers have reported similar results confirm ing the significant effect of ye근r of calving on various production and reproduction traits of buffaloes (Khan et al., 1989;and Rehman et al., 1988). They reported that YC had highly significant effect on CI in Nili-Ravi buffaloes.

Month of calving
In the present study, month of calving was found to have no effect on the other traits in Nili-Ravi buffaloes (table 2, figure 2). No reference could be found in the  literature reviewed showing effect of month of calving on various traits in these. buffaloes. Figure 2, however, showed that the buffaloes calving during January-February had highest TMY, LL and CI. Simil그rly buffaloes during the month of June had shown lower TMY, LL and CI. Table 4 gives the correlation of different traits with each other.

Lactation number：
The effect of LN on other traits such as TMY, LL and CI was found to be non-significant (table 2). Table 3 gives average TMY, LL and CI during different lactations. From this table, it was found that average TMY was highest during first three lactation (2,039 ± 83.56, 2,076 ± 83.56, 2,037 ± 94.18; respectively). The average TMY remained almost constant for another three lactations and then at seventh lactation the TMY average decreased considerably (1,454 ± 572.84) the number of observa tion in e견ch lactations are small making the above conclusion biased. Figure 2. Effect of month of calving on lactation yield, lactetion length and calving interval.

Calving interval
The C. I. had highly significant effect on LL (p < 0.01) and non-signiflcant effect on TMY and LN (ta비e 2). However, it had positive correlation with TMY (r=.28), although the correlation was found to be low (table 4). The average calving interval in the Nili-Ravi buffaloes was found as 467.98 ± 11.58 d. Other workers had reported C. I. of 482.1 ± 6.5 d in the same herd (Shafique and Usmani, 1996)

Lactation length:
Average LL in Nili-Ravi buffaloes maintained at LRS, Islamabad was found to be 277.42 ± 5.70 d (table 1). Lactation length and C.I were found influencing each other significantly (p < 0.001), Other factors had non significant effect on LL. Lactation length and TMY were highly correlated (r=0.64), and it had significant effect on TMY (p < 0.001). Other workers had reported high and significant correlated between LL and TMY (Javed et al., 1990;Chaudhary et al., 1970). They reported average LL of 258 d for Italian buffeloes. However, they reported Lactation number significant effect of MC and LL unlike present study where MC had no effect on LL. The LL varied in the present study from 122-614 d. This range should be restricted to 300 d making the bufifeioes efficient producer (Javed et al., 1990).