Research procedures were in accordance with the instructions permitted by Animal Care and Use Committee, University of Veterinary and Animal Sciences Lahore (UVAS). An experiment was conducted at the Small Ruminant Research and Training Center (SRTC), UVAS, Ravi Campus, Pattoki, Pakistan. Overall 24 animals (10±1 months old; body weight of 20±1 kg) were selected. The selected animals were divided into three treatment groups of 8 bucks in each group in a completely randomized design. Dietary treatments included conventional total mixed ration (TMR) containing CS having three different particle sizes: 1) 8 mm, CS8; 2) 16 mm, CS16; and 3) 24 mm, CS24. TMR was prepared by mixing the required quantities of CS and concentrate ingredients. All the diets were isocaloric and isonitrogenous in nature with a forage to concentrate ratio of about 75:25, respectively and were formulated as per the nutrient requirements suggested by National Research Council (
NRC, 2007) as presented in Table 1. The bucks were fed twice a day at 06:00 and 18:00 h throughout the study. The study lasted for 15 weeks, which included 2 weeks of adaptation, 12 weeks of data collection and 1 week for conducting digestibility experiment.
Behavioural activities of the bucks were recorded for 24 hours at d 14, 28 and 56 of the experimental study with the help of video camera (DAHUA HFW 3449 T1, China) mounted in the station. The parameters noted included feeding time bouts, its length, lying time bouts its length, rumination bouts and total rumination time in sitting and standing position. For digestibility measurement, intake of feed and output of fecal material were recorded from each animal on daily basis for five consecutive days. Nutrient digestibility of each experimental diet was calculated by using the following formula
(Blanco et al., 2014). The digestibility of nutrients were also determined by using above mentioned formula.
Rumen liquid was collected, four hours after morning feeding, at day 1, 28 and 56 of the trial by using oral tube. The collected rumen liquor was immediately filtered with the help of four layered cheese cloth for pH determination (Starter 3100, OHAUS and Parsippany, NJ, USA). Fecal scoring was performed on regular basis from 1 to 10 weeks by using 1 to 5 fecal scoring system with 1 for normal pellets and 5 for watery feces
(Jamber et al., 2007).
The diets were separated according to particle size by using Penn State Particle Separator of 3 mm screen which, in turn, distributed the particles into four different portions comprising long (19 mm), medium (8 mm), short (1.18 mm) and fine (1mm). Feed sorting activity was, then, determined by calculating actual DMI expressed as percentage of predicted DMI, for each fraction. Physical effectiveness factor of the ration was measured as the amount of particles recollected on 19 and 8 mm screen of Penn State Particle Separator, whereas physically effective NDF was determined by multiplying physically effective factor with NDF contents of the ration
Leonardi and Armentano, (2003). Values above 100% indicated better feed consumption, whereas below 100 indicated selective consumption. If the value was equal to 100%, it indicated no sorting of feed
(Overvest et al., 2016).
The blood samples were examined for phosphorous (Altair™ 240, Lab compare, South San Francisco, CA, USA) plasma urea nitrogen (PUN, 21516 © Biosystems and Barcelona, Spain), plasma glucose (GLUCOSE, 23503 © Biosystems, Barcelona, Spain), calcium (CA 0305 CH, Chema diagnostic), bilirubin (GP F 400 CS, SPHERA, Italy).
Statistical analysis
Data were analysed by one-way ANOVA method using SAS operating system (version 9.1). The following statistical model was used;
Yij = μ + ES i + eij
Where,
Yij = Dependent variable.
μ = Mean of the population.
ES i = Role of different particle size of CS.
e
ij = Residual effect.
