The study examined the effects of harvest time of red and white clover silage on eating and ruminating activity and particle size distribution in feed boli, rumen content and faeces in cows. The clover crops were harvested at two stages of growth and ensiled in bales. Red clover crops had 36% and 45% NDF in dry matter (DM) at early (ER) and late (LR) harvest, respectively, and the white clover crops had 19% and 29% NDF in DM at the early (EW) and late (LW) harvest, respectively. The silages were fed restrictively (80% of ad libitum intake) twice daily to four rumen cannulated non-lactating Jersey cows (588 6 52 kg) in a 4 3 4 Latin square design. Jaw movements (JM) were recorded for 96 h continuously. Swallowed boli, rumen mat, rumen fluid and faeces samples were collected, washed in nylon bags (0.01 mm pore size) and freeze-dried before dry sieving through 4.750, 2.360, 1.000, 0.500, 0.212 and 0.106 mm into seven fractions. The length (PL) and width (PW) values of rumen and faeces particles within each fraction were measured by use of image analysis. The eating activity (min/kg DM intake; P , 0.05) was higher in LR compared with the other treatments. The eating activity (min/kg NDF intake; P , 0.05) was affected by clover type with highest values for white clover silage. The mean ruminating time (min/kg DM), daily ruminating cycles (P , 0.001) and JM during ruminating (P , 0.05) were affected by treatment with increasing values at later harvest time. The proportion of washed particle DM of total DM in boli (P , 0.001), rumen mat (P , 0.001), rumen fluid (P , 0.01) and faeces was (P , 0.001) highest by feeding LR. There were identified two peaks (modes 1 and 2) on the probability density distribution (PDF) of PW values of rumen mat and faeces, but only one peak (mode 1) for PL values. There was no difference in the mean and mode 1 PW and PL value in rumen mat between the four treatments. The mean PL, mode PL, mode 2 PW and mean PW in faeces were highest for LR (P , 0.05). The mean particle size in boli measured by sieving was higher at white clover compared with red clover treatments (P , 0.001) and the highest value in faeces was found in LR (P , 0.01). The two peaks on PDF for width values of rumen mat and faeces particles are most likely related to the leaves and the stems/petioles. In conclusion, the mean total chewing activity per kg DM was lowest for the white clover silage and increased for both silages due to later harvest time. The mean particle size in boli was smallest for LR, whereas the mean PL and PW in faeces were highest for the LR.Keywords: legumes, cow, particle size, maturity, mastication ImplicationsThe lignification of structural fibre in white and red clover silage increases because of delayed harvest without affecting the mean ruminating and total chewing time per kg NDF. The distribution of particle length and width values in rumen contents and faeces reflects the indigestible NDF/NDF ratios in the different legume crops, whereas the 95% percentile length value in faeces did not differ be...

The study examined the effects of physical form and harvest time of alfalfa silage on eating and ruminating activity and particle size distribution in feed boli, rumen content and faeces in dry cows. The alfalfa crop was harvested at two stages of growth (early: NDF 37%, late: NDF 44% in dry matter (DM)), and from each harvest, a chopped (theoretical cutting length: 19 mm) and an unchopped crop was ensiled in bales. The silages were fed restrictively to four rumen cannulated non-lactating Jersey cows (391 ± 26 kg) in a 4 × 4 Latin square design. The cows were fed restrictively 80% of theirad libitumintake twice daily. Chewing activity was recorded for 96 h continuously. Swallowed boli, rumen content, rumen fluid and faeces samples were collected, washed in nylon bags (0.01 mm pore size) and freeze-dried before dry sieving through 4.750, 2.360, 1.000, 0.500 and 0.212 mm pore sizes into six fractions. The length (PL) and width (PW) of particles within each fraction was measured by the use of image analysis. The eating activity (min/kg dry matter intake (P< 0.01) and min/kg NDF (P< 0.05)) was affected by harvest time. The mean ruminating time (min/kg DM) was affected by harvest time (P< 0.01), physical form (P< 0.05) and NDF intake per kg BW (P< 0.01). The proportion of washed particle DM of total DM in boli, rumen content, rumen fluid and faeces was affected by harvest time (P< 0.01) and highest by feeding late-harvested alfalfa silage. Two peaks on the probability density distribution function (PDF) of PW and PL values of boli, rumen content and faeces were identified. Chopping of the silage decreased the mean PL and PW, the most frequent PL (mode) and 95% percentile PL and PW values in boli. In the rumen content, chopping increased the mean PW (P< 0.05). The dimension sizes of faeces particles were not significantly affected by chopping. The mode PW value was lower in rumen content and faeces than in boli (P< 0.001), and the mode PL value was higher in boli and lower in faeces compared with rumen contents (P< 0.001). In conclusion, the mean total chewing activity per kg NDF decreased due to chopping and early harvest time. The mean PL and PW in boli decreased due to chopping and late harvest. The two peak values on the PDF (PL) and PDF (PW) of boli, rumen content and faeces particles are most likely related to the leaf and the stem residues.