Place of the study: The present study was conducted at the Cattle farm, Patutia BLRI, Savar, Dhaka-1341. Laborato ry works were conducted in the Animal Production Research Division (APRD) and Animal Health Research Division (AHRD), BLRI, Savar, Dhaka - 1341.
Experimental animals and dietary treatments: A total of 24 local calves (BLRI Cattle Breed-1/Pabna; 20 calves and Red Chittagong Cattle; 4 calves) of about 6-10 days of age were selected and divided in four groups; having six (6) calves in each. The unavailability of Pabna calves during the study period was the main reason to include 4 RCC calves under the research program. However calves were distributed randomly in each treatment group. The calves were reared under group feeding management practices followed in BLRI cattle farm. A limited suckling with feeding whole milk considered as control (T0), suckling along with feeding of wheat, shoti and soybean based milk replacer considered as treatments and denoted as T1, T2 and T3 respectively. However, the amount of milk fed by the calves under both groups (control & treatment) through suckling in the morn ing and evening were quantified through weighing calves just before and after suckling with the help of a platform digital balance.
Housing and feeding experimental diets: The calves were housed in an open calf shed, where group - feeding approaches were practiced. The calf shed provided with feed trough for feeding concentrate mixture and green grass and a plastic bucket for feeding water. All calves under control and treatment groups were supplied an iso-nitrogenous diet (CP content 2 5 %) at a rate of 10% of their body weight. Calves fed whole milk or milk replacer twice daily at 08:00 and 16:00h using a plastic bottle. Before feeding the calves, fresh milk was collected from bulk collection, filtered to remove extraneous materials and boiled at 1000C for 20 minutes. Then, it was cooled to 370C and supplied to the calves. Incase of replacer, the formulated powder was added in hot boiled water maintaining a ratio of 1:7 (milk replacer powder: water), so that the protein content of liquid milk replacer contain ed similar to milk and cooled down to 370C and then fed to calves. Green grass and concentrate mixture were supplied adlib after 2 weeks of age. The experiment was carried out for a period of 50 days.
Measurement of body weight: The calves were weighed initially just after arrival and weekly thereafter by a platform digital balance. Each calf was weighed in the morning before feeding. The experiment was carried out for a period of 50 days. The total live weight gain was calculated by subtracting the initial weight from the final weight taken at the end of the experimental period and the daily weight gain was calculated by dividing the total weight gain by the number of experimental days.
Measurement of intake: The daily feed intake was measured by subtracting the amount of refusals from the amount of feed offered in the previous day. During feeding trial, the total intake i.e., the actual intake of milk, milk replacer, amount of green grass and concentrate fed by the animals were recorded on daily basis. Incidences of diseases were also observed daily to evaluate the health status of calves.
Chemical analysis of experimental diets: Representative samples of feed, milk replacers and whole milk were chemically analyzed for dry matter, organic matter, crude protein and crude fiber following the method of AOAC (2005). The acid detergent fibre (ADF) was determined as per Goering and Van Soest (1970). The percent fat and protein content in milk samples were also determined by using a Lactostar (Funk e Gerber, model no. 3510 - 080203 ) .
Blood Collection and Plasma biochemical assay: The blood samples were collected in the morning prior to feeding of the calves especially from jugular vein into EDTA (20 IU heparin/ml blood) tubes at fortnightly interval. Immediately after sampling, the blood was placed in ice box and taken to laboratory. To separate plasma from the cells, blood samples were centrifuged at 3000 rpm for 15-20 minutes and the plasma wer e separated and stored in refrigerator (-200C) in different aliquots for the analysis of blood urea nitrogen (BUN) and plasma glucose. The blood urea nitrogen and glucose were determined by using a commercial kit (blood urea nitrogen kit & blood glucose kit) at Serology laboratory under Animal Health Research Division, BLRI, Savar, Dhaka-1341.
Statistical analysis: Data were subjected to analysis by using analysis of variance (Steel and Torrie, 1980) for a Completely Randomized Design (CRD). Treatment mean s were compared by using LSD. All the analysis was carried out using SPSS (2002) programme.