The present research project bears the novelty of use of non-conventional energy source in form of by-pass fat supplementation to enhance milk production in indigenous dairy cattle.
Present study was conducted to evaluate the effect of by-pass fat supplementation on milk production, composition and weight gain in Sahiwal cows. Twelve dairy cows of same parity, stage of lactation, milk production level and body weight (285-360 kg) were randomly allotted to four treatments (T0, T1, T2 and T3) in such a way that each group had 03 animals under Completely Randomized Design. The animals received 250g, 350g and 450g of supplementation in T1, T2 and T3 whilst animals in T0 served as control group. All animals were maintained under similar managemental conditions. The data of milk production (daily/individually), milk composition and body weight were weekly recorded. The data recorded was statistically analyzed and results revealed that milk production and composition differed significantly (p(<0.05) in all groups. The highest milk yield was found in T2 (10.45±0.53 Kg) and the lowest (6.93±0.53 Kg) in control group that was without by-pass fat supplementation. The T2 and T3 differed not significantly for milk yield and composition. Almost all the milk constituents showed the same trend. The body weight gain differed non-significantly in all groups. The milk cost showed significant differences in all treatments. The lowest cost (Rs. 32.20±2.37) was shown in T2 and the highest (Rs.46.14±2.37) in T3 group. Therefore, 250g is the optimum amount of supplementation tp produce milk economically with high fat percentage.
Key words: Bypass fat, milk production, milk composition, body weight, dairy animal.
Livestock farming is an integral part of the prevailing agricultural system in Pakistan. A deficiency gap of 4.16 and 21.3 million tons of crude protein (CP) and total digestible nutrients (TDN), respectively has been reported by Sarwar (2006). During early lactation, the energy necessary to replenish body reserves and maintain high milk production is higher than the available energy from daily feeding (Goff and Horst, 1997) which may lead to mobilization of body fat to coop the deficiency. High milk producing animals during early production face negative energy balance leading to metabolic pressure and sub-optimal yield of milk (Drackley, 1999). By-pass fat increases fat corrected milk (FCM) and its proportion in milk composition (Rodriguez et al., 1997). The FCM and milk fat proportion is enhanced without disturbing the digestibility of other supplements and it avoids the degradation of supplements and bio-hydrogenation in rumen leading to increasing energy density of the ration (Elliott et al., 1996). The higher milk yield and fat content is direct benefit to farmers (Parnerkar et al., 2010). The rumen fermentation process is not affected by bypass fat but it provides additional energy to the animals for more milk production after being absorbed in the small intestine (Bobe et al., 2007). It also supports production of unsaturated fatty acid in the milk which is easily digestible for patients with heart disease (Garg et al., 2008). Calcium (Ca) salts of long chain fatty acids (LCFAs) and prilled saturated (FAs) fatty acids are more effective as bypass fat for lactating animals (Palmquist, 1991) as extra energy source. The previous work by different scientists on the supplementation of by-pass fat in milking animals under different managemental situations (Naik, 2013: Relling and Reynolds, 2007) but no work has been reported in indigenous dairy animals with different levels of supplementation. Therefore, this study was planned to investigate the effect of supplementation of different levels bypass fat on the production of milk, weight and composition of milk in Sahiwal lactating cows.
Experimental design and arrangement of animals: The trial was conducted at the Livestock Experiment Station of Directorate of Farms, University of Agriculture Faisalabad. Twelve Sahiwal dairy cows of same parity, lactation stage and milk production level were randomly allotted to four treatments (T0, T1, T2 and T3) in such a way that each group had 03 animals. All the precautionary measures were taken to control the seasonal diseases and parasitic infestation by using the vaccination for FMD and HS as per schedule of the farm. The experimental animals were managed in individual stalls under uniform climatic conditions.
Feeding management and treatments: Green fodder was offered ad libitum (at least 10% refusal) twice a day. Fresh water was available round the clock. Compound feed was offered @ 3kg twice a day including the fat supplement. An energy supplement with calcium salt of long chain fatty acids for dairy animals was used as bypass fat. The bypass fat was supplemented in group T1 @ 250 g day-1 animal-1, group T2 @ 350 g day-1 animal-1 and in group T3 @ 450 g day-1 animal-1. Animals of group T0 will be taken as control (without bypass fat). The composition of different treatment ration is given in table 1.
Sample collection and analysis: Approximate analysis of the compound feed along with supplement was done using techniques described by AOAC 2005 (Table 1). The data of daily milk production of both milking (morning+evening) for individual animal was recorded. The weekly milk samples of individual animals were collected and used for milk analysis in Dairy Lab. of Inst. of Dairy Sciences. Milk fat and protein was determined by Gerber (Aggarwala and Sharma, 1961), and Kjeldhal methods (Davide, 1977), respectively. Total solids (TS) and solid not fat (SNF) was calculated according to Fleischmann’s formula. The experimental animals were weighed weekly basis to check change in weight.
Statistical analysis: Data generated for milk production and milk composition for protein, fat, solid not fat (SNF) & total solid (TS) and body weight for seven weeks was analyzed statistically under completely Randomized Design using computer software MINITAB (2000, version 17.0) and the significance of means was compared using the Tuckey’s test to draw the valid conclusion at certain significance level.
Milk Production and Composition: Analysis of the data for milk production on by-pass fat supplementation revealed that milk production differed significantly (p<0.05). The highest milk production (10.45±0.53 Kg) was observed in T2 and the lowest values (6.93±0.53) were found in treatment T0 (Table 2). The milk production in T3 where supplementation was given @ 350 g/animal differed significantly with all other treatments except T2. The control group and T4 group differed non-significantly (Table 2). Animals in T3 gave 3.52 Kg more milk than control and 1.49 and 2.82 Kg more milk than T2 and T4 respectively. The animals in T3 group on an average produced 50% more milk than control group.
The milk composition also differed significantly (p<0.05) in all treatments. The highest fat % was observed in T4 (4.49±0.02) and the lowest % (4.03±0.02) was found in control group. T3 and T4 group differed non-significantly (p<0.05). In group T3 where animals showed the highest milk yield 4.26±0.02 % fat was found and it was non-significant with highest fat producing group.
The solids not fat (SNF) percentage also showed the similar pattern. The T3 and T4 showed non-significant differences for SNF. Protein and Total solids % showed non-significant differences.
There Cost per kg milk produced in differed groups varied significantly (Table 3). The highest cost (Rs. 46.14±2.37) was revealed in group T3 whilst the lowest was found in animals on T2 where 350g supplement was offered. The highest cost feeding cost was observed in group 4 (Rs.356.00) and lowest in control group (Rs.280.00). The milk cost between T2 and T1 did not differed significantly
Milk production: Average milk production (kg) animal-1 day-1 with by-pass fat supplementation was significantly (P<0.05) increased in T2 (10.45±0.53). It was observed that with the increase in fat supplementation milk production was enhanced in T1 (250 g day-1animal-1) and group T2 (350 g day-1animal-1) but there was no significant (P>0.05) change in group T3 (450 g day-1animal-1). It might have improved their energy demand with supplementation of by-pass fat. The animals on T0 showed significantly lower milk yield as compared to T2 and T1, it might be due to that animals were maintained only on basal ration. The animals maintained on T3 (450 g day-1animal-1) also showed a non- significant difference in milk yield as compared to T0 it may be concluded that milk yield on higher level of by-pass fat supplementation (> 350 g day-1 animal-1) depressed the milk yield. A probable cause of this trend might be disturbed energy:protein ratio. The higher level of by-pass fat supplementation might have affected the nutrients intake with increased level of by-pass fat intake in T3. The results of the present study are in line with Barley and Baghel (2009) who reported that the milk production and fat was increased in dairy animals by supplementation of bypass fat. Garg and Mehta (1998) also revealed that without disturbing the dry matter intake, the milk yield was significantly increased by the feeding of by-pass fat. Significant improvements in milk production was observed in lactating cows by the supplementation of by-pass fat (Purushothaman et al., 2008). Dhiman et al., (1995) reported that by-pass fat preserves the nutrients degradation and bio-hydrogenation in rumen with improved energy density of the ration supporting the animals to meet energy demand and fatty acid requirements to express their milk production potential.
Milk composition: Milk fat % was improved significantly with the bypass fat supplementation in all the groups. The e group T3 (4.49±0.02) showed most significant results than all other treatments. In group T3 there was 10.24% increase in fat from T0 but 5.90% and 5.12% increased from T1 and T2 respectively. All the results of increasing fat percentage in milk of dairy cows may be due to the supplementation of bypass fat in the ration of dairy animals. However the effect of bypass fat supplementation on milk fat percentage depends on the profile and level of calcium salt of long chain fatty acids (Chouinard et al., 1997; Sklan et al., 1991). However, in some studies non-significant effect was also reported (Naik et al., 2009). The Protein content had shown non-significant (P>0.05) results by the supplementation of bypass fat. It was decreased with the supplementation of by-pass fat, might be due to increase in milk quantity and fat percentage content. Loss in milk protein % had been associated to the dilution of milk protein, as higher milk volume produced might not be coordinated with uptake of amino acids by the mammary gland (DePeters and Cantt, 1992). Solids not fat (SNF) percentage had shown non-significant (P>0.05) results in all the treatments. It had already been reported that SNF content of milk is not altered (Naik et al., 2009; Tyagi et al., 2009; Thakur and shelke, 2010; Sirohi et al., 2010) or improved (Wadhwa et al., 2012). The total SNF production is enhanced due to increase in milk yield (Naik et al., 2009). The study had shown non-significant weight gain among all groups. The present finding has been supported by work of (Purushothaman et al., 2008, (Wadhwa et al., 2012).
The results of present study indicated that by-pas fat can be used successfully in indigenous dairy animals economically with significant increase in milk and fat yield. The high amount of supplementation will not increase yield and fat% accordingly and will increase milk cost per unit.
The authors are very thankful to “MJ Foods and Dairies” for providing “MJ Synerlac” (bypass fat) and also for financial support to carry out this study.