Effect of Level of Feeding on the Performance of Crossbred Cows during Pre-and Post-partum Periods

The study was undertaken to see the effect of elevated feeding during pre-partum or preas well as post-partum period on the productive and reproductive performance of crossbred cows. The experiment lasted for 60 d pre-partum to 120 d post-partum. Eighteen dry pregnant crossbred cows divided into three equal groups were fed either as per NRC feeding standard (C) or 20% above NRC during 60 d pre-partum (T1) or fed 20% above NRC during both 60 d pre-partum to 120 d post-partum (T2) period. During prepartum period body weight gain was significantly (p≤0.05) higher in T1 and T2 groups than that of control group. The animals fed at higher plane of nutrition (T1 and T2) took significantly lesser time for complete relaxation of pelvic muscles, act of calving and for expulsion of placenta than that of control group. Moreover, such cows delivered 2 to 3 kg heavier calves as compared to normal fed dams. During post-partum period, the average daily milk yield was significantly higher in T2 group than that in T1 and control groups. The peak yield was significantly higher in T2 group, it took longer time to reach peak production but it was more persistent in this group as compared to T1 and control groups. Average milk fat, solids-not-fat (SNF) and total solids were significantly higher in T1 and T2 groups as compared to control group. Body weight losses incurred during early lactation were not even compensated by end of 4th month of lactation in C and T1 groups whereas the animals in T2 group gained 2.0 kg. The 1st post-partum estrus and conception rate were better in high fed groups (T1 and T2) than that of control group. The returns over feed cost of milk production were higher in T2 group followed by T1 and control groups indicating the advantage of elevated feeding during preand post-partum periods. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 12 : 1749-1754)


INTRODUCTION
In developing countries, more than 70% of the expenditure, in dairy farming is on the feeding of animals.Most of the farmers are, not aware of the benefits of quality feeding and that of balanced diet.Even, a few, progressive farmers also, think about the feeding strategy once the cow has given the birth to a calf, which is similar to the saying "Start digging a well once you are thirsty".Rather, there should be a well-planned feeding and management schedule, for the transition period (last phase of gestation and ensuing lactation).Improper feeding (under-or over-) during this phase could lead to low birth weight of newborn calf, postpartum estrus and obviously low productive performance of cows (Sasser et al., 1988;Qureshi, 1995).However, comprehensive reports on nutrition-production-reproduction inter-relationship are not available.This study was, therefore, planned to see, how the plane of nutrition during pre-partum period or during complete transition (pre-as well as post-partum) period, affects the productive and reproductive performance of dairy cows.The goal of this feeding program is to provide the correct amount and balance of nutrients to cows at the proper time to achieve optimum production, reproductive efficiency and profitability.

Feeding and management
Eighteen dry pregnant crossbred cows and heifers were selected from the dairy herd of the university on the basis of parity, body weight, previous lactation yield and expected date of calving (Table 1).The experiment lasted 60 d prepartum to 120 d post-partum duration.The animals divided into three equal groups were offered feed either as per NRC (1989) feeding standard (C) or 20% above NRC only during 60 d pre-partum period (T 1 ) or 20% above NRC during 60 d pre-partum to 120 d post-partum period (T 2 ).During prepartum phase, the animals were offered concentrate mixture (Table 2) once-a-day at 9:00 h followed by seasonal green fodder mixed with wheat straw (50:50) at 11:00 h.The roughage to concentrate ratio was 70:30 during the prepartum period.During post-partum phase, the concentrate was offered at the time of milking in the milking parlour.
The animals were fed individually.Water was available to the animals around the clock.The animals were weighed for 3 consecutive days at each fortnight.The animals were kept in semi-loose housing system.Two weeks prior to expected date of calving, the animals were shifted to individual maternity pens, so as to provide utmost care during advanced pregnancy.Immediately after parturition, the animals were closely watched for incidence of any metabolic disorders like parturient paresis, ketosis and other diseases like mastitis, which were treated accordingly by the Animal Health Specialist.

Reproduction parameters
The signs of oestrus were detected by bull parading.This practice was followed regularly daily in morning and late in the evening.The animals in heat were also detected from different signs such as bellowing, mounting over other animals, less interest in feed and vaginal discharge.
Calving observations : The calving observations were recorded for the following traits: i) Loosening of pelvic muscles : The time of relaxation of sacrosciatic ligaments and sinking of croup (a part of hind quarters lying immediately behind the loin) muscles before parturition.
ii) Start of labour : The animals were watched for initiation of labour and time was recorded when parturition symptoms like nervousness, restlessness, loss of appetite and change in posture (sitting, standing and walking in semi-circles), frequent micturition, occasional glances at the flank and stamping the ground with limbs etc. tended to appear.
iii) Time taken for act of calving : It comprised of complete dilation of the os-uteri to the delivery of the foetus.It started from the appearance of water bag at vulva till the complete expulsion of calf.The cleaned and dried calf before feeding colostrum was weighed within an hour after its birth.iv) Time taken for expulsion of placenta : The time interval between expulsions of calf to the expulsion of placenta.
v) Post-partum reproductive efficiency : It was measured from post-partum oestrus interval, number of inseminations per conception, and conception rate etc. Animals detected in estrus in morning were inseminated in the evening on the same day and those detected in heat in the evening were served next day in the morning.

Milking and composition of milk
The cows were milked in milking parlour 2 to 3 timesa-day by using milking machines and milk yield of each crossbred cow was recorded daily during first 4 months of their lactation.Milk samples of each animal were analysed, at fortnightly interval, for fat, solids-not-fat, protein and lactose by automatic milk analyser (Milkoscan 133B).

Digestibility of nutrients
It was assessed by indicator method, using chromic oxide green as an external marker at the rate of 0.2% of daily dry matter intake, for 10 d as adaptation period followed by 7 d collection period.Grab samples of faeces were collected directly from rectum twice daily i.e. at 8:00 and 16:00 h and dried in forced air oven at 80°C.

Analytical methods
The finely ground samples of feed, feed residue and faeces were analysed for proximate principles (AOAC, 1984).Cellulose (Crampton and Maynard, 1938), other cell wall constituents (Robertson and VanSoest, 1981) and chromic oxide (Hill and Anderson, 1958).The data was analysed by using completely randomised design (Snedecor and Cochran, 1968).

RESULTS AND DISCUSSION
The chemical composition of different feedstuffs, offered to the animals, revealed that amongst the forages, the Egyptian clover, being leguminous, had the highest CP and lowest cellulose content (Table 2).Wheat straw had the lowest CP and highest cellulose content amongst the feedstuffs selected.
The animals, in the experimental groups, consumed significantly (p<0.05)higher quantity of concentrate mixture, green fodder and wheat straw, both during pre-and peri-partum periods, as compared to those in the control group resulting in significantly (p<0.05)higher total daily DM intake (Table 3).The concentrate mixture, green fodder and wheat straw contributed 29.4,32.9 and 37.7% of DM, respectively.
The live weight of all the animals, at 60 d pre-partum, was comparable, thereafter; it increased linearly in all the groups.The average body weights one day before calving were significantly higher (p<0.05) in experimental than those in control group (Table 3), which could be due to improved nutritional status of animals in T 1 and T 2 groups.More live weight gain in animals, fed at higher plane of nutrition, during 55 to 60 days pre-partum period have also reported by Kale and Tomar (1991) and Prasad and Tomar (1995a).Qureshi et al. (2002) showed that ME intake, above requirements during pre-partum period resulted in higher body condition score in dairy buffaloes.The peripertum losses were significantly (p<0.05)higher in animals of T 1 and T 2 groups (13.1 and 14.9%) as compared to those in control group, which could be due to birth of heavier calves in experimental groups (8.5% more weight).
The animals, kept on higher plane of nutrition during the pre-partum period (T 1 and T 2 ), took less time for, complete relaxation of pelvic muscles (17.0 and 12.5%), calving (19.5%), and expulsion of placenta (16.5%) and had significantly (p<0.05)lesser weight of placenta (38 and 27%) than the animals in control group (Table 4).Similar observations about calving have also been reported (Yadava et al., 1976;Little and Harrison, 1981;Prasad and Tomar, 1995b).
During post-partum period the daily DM intake was significantly higher (p<0.05) in T 2 group as compared to that in C and T 1 groups (Table 5).The comparable DM intake in C and T 1 group, during post-partum period, was because these animals were offered diet at same feeding level i.e. 100% NRC.The roughage to concentrate ratio (70:30) followed during pre-partum period was narrowed to 55:45 in order to meet the increased nutrient requirements during post-partum period for milk production.The ratio of green fodder to wheat straw was also changed from 50:50 to 62:38.The DM consumption increased linearly up to 3rd fortnight and thereafter, it declined gradually.Garnsworthy and Topps (1982) also reported linear increase in voluntary DM intake after parturition so as to meet the increasing demands of nutrients for milk production up to 45 to 50 d.
The average daily milk yield, throughout the experimental period, was significantly higher (p<0.05) in animals fed 20% above NRC standard during pre-and postpartum period as compared to those fed as per NRC standards or fed 20% above NRC standards, only during pre-partum period (Table 5) indicating, that higher plane of nutrition both during pre-and post-partum period, could    (1982) and Gargantini et al. (1984) reported a significant increase in milk production due to higher pre-and postpartum feeding levels.However, Lodge et al. (1975) failed to establish the significant effects of higher pre-partum feeding on milk production.Khan et al. (2002) reported that ad.libitum feeding of crossbred cows during last trimester of pregnancy resulted in deposition of fat, gain in weight during pre-calving period and produced less milk during post-calving period.The animals in T 2 group took longer period to reach peak production but the peak was more persistent in than C and T 1 groups.The peak yield was significantly higher in animals in T 2 group than those in C and T 1 groups.Johnson (1979) also reported higher peak yield in animals fed at higher level than those fed at low level of nutrition.The higher level of feeding during pre-partum period alone or both during pre-and post-partum period had improved the quality of milk significantly (Table 6).The improvement was 11 to 13% in fat, 2 to 3.6% in SNF and 5 to 7% in total solids with the improvement in nutritional status of the animals.Similar trend was observed in case of protein content (1.7 to 3.4%) also, but the differences were statistically non-significant.Treacher et al. (1986) and Holter et al. (1990) also observed similar trend in animals fed at higher plane of nutrition than those at lower plane of nutrition.The lactose secretion in milk has been reported to be independent of nutritional status of the animal (Kunz et al., 1985), but quantum of milk in the udder affect its concentration that is why the low yielding cows (control) had higher concentration of lactose as compared to high yielding animals in T 1 and T 2 groups, respectively.Treacher et al. (1986) also observed low lactose level in fat cows (4.66%) as compared to thin cows (4.77%).
Post-partum body weight changes revealed that the average live weights of experimental animals one day after calving were 438, 464 and 459 kg in C, T 1 and T 2 groups, respectively which declined sharply in all groups to 415, 441 and 438 kg in respective groups by 3rd fortnight indicating that the stress of pregnancy followed by initiation of milk secretion lead to body weight losses during early lactation.As the stress reduced, animals started gaining weight and the animal fed at higher plane of nutrition gained more weight as compared to those fed as per NRC during 4th to 8th fortnight (Figure 1).The overall gain/loss in body weight of animals fed as per NRC standard, 20% above NRC only during pre-partum period and 20% above NRC both during pre-and post-partum periods was -9.28, -4.24 and 2.00 kg, respectively.Similar trends in body weight losses of dairy cows have been reported by Khatkar et al. (1992).
The first post-partum oestrus was observed much earlier (p<0.05) in animals fed at higher plane of nutrition during pre-partum (T 1 ) or during pre-as well as post-partum periods (T 2 ) than the animals fed as per NRC standard (Table 7).It could be due to body weight loss, which might have affected the initiation of ovarian activity after calving.Yadava et al. (1974) also observed earlier exhibition of 1st post-partum oestrus in high fed animals (48 d) as compared to low fed animals (51 d).The elevated feeding level during pre-as well as post-partum period (T 2 ) resulted in significantly higher conception rate (83.3%) as compared to animals offered higher plane of nutrition only during prepartum (T 1 ) period (66.7%) which in turn was significantly higher than animals in control group (50%).McClure (1965) reported that loss in body weight during early lactation resulted in low blood glucose concentration, which is positively correlated with conception rate.However, the service period was extended significantly (p<0.05) in T 1 and T 2 as compared to cows in control group.Treacher et al. (1986) also observed longer service period in fat cows (98 d) as compared to thin cows (89 d).
The cows in T 1 and T 2 groups produced 151 and 391 kg extra milk over their counterparts in control group (Table 8).The sale price of milk in Rupees (Rs.) was calculated on the basis of milk fat and SNF content.Although the feed cost per kg of milk production was comparatively more in T 2 group (Rs.4.84) followed by control group (Rs.4.38) and T 1 group (Rs.4.36).However, the return over feed cost per kg of milk production was found to be maximum in T 1 (Rs.2.66) followed by T 2 (Rs.2.31) and control group (Rs.2.22).So, the returns per cow were also more in T 1 and T 2 groups.Flaherty (1993) also observed similar results.The results, conclusively revealed that feeding of dry pregnant animals at higher plane of nutrition should start, not only during 60d pre-partum but the same plane should be continued 120d post-partum , so as to improve productive and reproductive performance of high yielding cows and to make dairy farming more economical as indicated by cost/benefit ratio.

Table 1 .
Distribution of experimental animals

Table 3 .
Effects of level of feeding on DM intake and live weight changes during pre-and peri-partum periods

Table 4 .
Effect of level of feeding on time taken for different calving observations Different superscripts in a row differ significantly (≤0.05).

Table 5 .
Effect of level of feeding on milk production

Table 6 .
Effect of level of feeding on composition of milk (%)

Table 8 .
Economics of milk production in crossbred cows