Experiments were conducted at the Livestock Research Centre, Southern Regional Station, ICAR-National Dairy Research Institute (NDRI), Bangalore, India in the year 2014. The latitude, longitude and elevation of the experimental place are 12.947014
oN (12
o 56' 49.2504" N), 77.607679 (77
o 36' 27.6444" E) and 921 m MSL, respectively. The tropical climate is considered to be Aw (Savanna, wet) according to the Köppen-Geiger climate classification with a mean temperature of 23.6
oC and 831 mm annual rainfall. The variation in temperatures throughout the year is 6.4
oC. During the experimental period, the relative humidity ranged from 59 to 73%, the mean ambient temperature was 72 to 79
oF and the mean heat index was 77 to 82
oF. The experiment was carried with the approval of the Institute Animal Ethics Committee (IAEC) and reared as per the guidelines of the Committee for the Purpose of Control and Supervision of Experiments (CPCSEA), New Delhi, India.
Twenty Deoni cows in 116±9 d of lactation were distributed in a completely randomized block design to 5 groups with 4 replicates based on mean milk yield (3.63±0.26 kg), body weight (352±9 kg) and parity (3.5±0.5). Cows housed in well ventilated, individual pens and provided
ad lib water 6 times a day and dewormed before starting the experiment. The basal roughage was finger millet (
Eleusine coracana) straw (FMS) and fed
ad-lib twice a day. The balanced nutrients (
NRC, 2001) were met through a concentrate supplement consisted 92.7% sorghum grain as control (CG) or treatment groups (TG) consisted of 93.24% wheat bran (T1), 94.10% hyacinth bean grit (T2), 92.74% soy husk (T3), or 91.94% green gram grit and Bengal gram husk in 50:50 ratio (T4). All 5 types of concentrate supplements were made iso-protein (18%) by balancing with commercial urea at the rate of 2.93%, 1.76%, 2.26%, 0.90% and 3.05% in CG and TGs, respectively. All the concentrate feed mixtures (CFM) were fortified with 2% common salt and 3% minerals and vitamins mix (M/s Neospark Drugs and Chemicals Pvt. Ltd., India). Concentrate mixture was offered 2.4 kg/day/cow in 2 equal parts soon after milking at 6 AM and 5 PM every day.
After 4 weeks of the preliminary period of feeding, a digestibility trial for 5 days was conducted. Total faeces collected in the 24 hours cycle were weighed, a part was kept for oven drying at 100±1
oC overnight and another part was acidified with 25% H
2SO
4 (v/v) in a glass bottle for nitrogen estimation. Spot urine from the cows was collected 100 mL/day in a bucket acidified with 10% H
2SO
4 (v/v). Acidified urine samples were diluted with distilled water (DW) uniformly to 1.2 L, filtered through glass wool and 50 mL was stored at -20
oC in polypropylene bottles. FMS, CFM, orts and faeces samples were processed through a cutting Willey mill using a 1 mm sieve. These samples were analyzed for proximate chemical and cell wall constituents according to
AOAC (2012). Total carbohydrates (TCHO), non-fibrous carbohydrates (NFC) and hemicelluloses were mathematically calculated
VanSoest et al. (1991). Energy parameters were calculated using empirical formulae (
ARC, 1980). Milk yield was recorded daily and expressed as 4% fat corrected milk (FCM). Morning and evening milk samples were analyzed for total solids (TS), milk fat, milk protein and solids-non fat (SNF) as per the standard methods
AOAC (2012).
Rumen MBP production was quantified based on the urinary excretion of creatinine and purine derivatives
(Chen et al., 1995). Diluted spot urine samples were thawed and treated with uricase to degrade uric acid to allantoin and other compounds. Uricase (U-9375, M/s Sigma Chemicals Co, USA) was prepared in phosphate buffer (0.67 M KH
2PO
4, adjusted the pH with KOH) to obtain a concentration of 0.12 units/mL. One ml of phosphate buffer was added to 2.5 mL of diluted urine sample in the test tube and mixed thoroughly to add 150 µL of uricase solution with pH adjusted to 9.0 by NaOH. Tubes were incubated for 2 hours at 37
oC. Total allantoin and creatinine in urine samples were determined by the colorimetric method
(Chen et al., 1995). The duodenal flow of MBP was calculated based on the total purine derivatives (PD) and creatinine (PDC) index. The endogenous contribution of PD in indigenous cattle was taken as 0.147 W0.75 per day (
Chen and Ørskov, 2005). The efficiency of MBP production was expressed as gN/kg of digestible OM intake (DOMI) and gN/MJ ME.
Weekly milk yield and composition of CG and TGs were subjected to the MANOVA model including the repeated measure. Data were subjected to variance tests using a completely randomized block design (CRD). Group means were compared by Duncan multiple range tests (DMRT) at 5% probability (α<0.05). These analyses were carried with statistical packages for the social sciences (M/s IBM India Pvt. Ltd., SPSS v 14.0).