Four experiments were conducted with dairy cattle to determine the effects of initial feed particle size and moisture content on particle size of ingested masticates. Three mature Holstein cows were used in either latin square or Youden square designs. Samples of masticated and ingested boli were collected at the cardiac opening through a ruminal fistula between 0 and 5, 5 and 10 and 10 and 15 min after meal initiation. In Exp. 1, masticate log mean particle sizes (LMPS) (ln microns, log normal distribution) were 3.50, 3.53 and 3.50 for corn silage, fine-chopped alfalfa haylage and coarse-chopped alfalfa haylage, respectively. In Exp. 2, boli LMPS for ground, chopped and long alfalfa hay were 3.11, 3.76 and 4.09, respectively. Boli LMPS in Exp. 3 for ground, chopped and long timothy hay were 2.93, 3.12 and 3.03, respectively. Exp. 4 compared the effect of addition of water to produce 30%, 47%, 64% and 82% DM in chopped alfalfa hay. Boli LMPS were 3.66, 3.56, 3.64 and 3.68 for the respective alfalfa hay DM contents. Feed LMPS was not reduced during mastication in Exp. 4, nor were there differences in LMPS due to time after feeding. Boli LMPS was affected by feed particle size of alfalfa hay, but there was no effect of feed particle size on masticate particle size in timothy hay. The magnitude of particle size reduction during mastication appears to be dependent on forage type and is not dependent totally on initial feed particle size and DM content of forages.

Abstract. Experiments conducted by Lifetimewool at plot-scale have shown that differences in the maternal liveweight during pregnancy and lactation (liveweight profiles) of individual Merino ewes influences their wool production and reproductive rate as well as the birthweight, survival, weaning weight and lifetime wool production of their lambs in a predictable manner. This study determined whether these impacts of nutrition of the ewe on ewe and progeny performance are measurable on commercial properties across southern Australia at a paddock-scale where ewes were aggregated into flocks with a greater spread of the date of conception and where the liveweight profile of the flocks were managed based on random samples of 100 ewes and liveweight was uncorrected for fleece weight or conceptus. Eighteen paddock-scale experiments at 15 sites were conducted in cooperation with wool producers across Victoria, Western Australia, New South Wales, South Australia, and Tasmania. Each co-operator joined up to 1000 mixed aged adult Merino ewes. The flock was scanned using ultrasound at Day 50 from the start of joining to identify those ewes that conceived during the first 21 days of joining. These ewes were then split at random into two treatments and fed to achieve a target difference in liveweight of 10 kg or~1 condition score/fat score at lambing. The production of ewes during their year of pregnancy and following their next joining was measured as was the performance of their progeny up to their third shearing. Only the 13 paddock-scale experiments that achieved a difference in liveweight profile at lambing of at least 4 kg were included in the final analysis. In these 13 experiments, increasing the nutrition of Merino ewes during pregnancy clearly increased the clean fleece weight and fibre diameter in ewes and the survival and lifetime wool production of their lambs. In most cases the size of the effect was not significantly different to that predicted by the relationship derived using individual liveweight profiles in the plot-scale experiments. This confirms that managing average ewe liveweight or condition score/fat score profile through better nutrition will lead to predictable increases in the performance of ewes and their progeny performance under commercial conditions and validates the use of the plot-scale relationships in economic analyses.

The aim of this study was to evaluate the effects of the substitution of maize silage (MS) for urea-treated rice straw (URS) in feedlot diets on finishing performance and body conformation traits of culled local Yellow cows; and to develop prediction equations for live weight (LW) of local Yellow cows using these body measurements. Twelve non-pregnant local Yellow cows (74.8 ± 23.6 months of age) were blocked by weight into 4 groups and then randomly allocated to one of three roughage treatments: 30% fresh maize + 70% URS (DM basis) (Control); 30% fresh maize + 40% URS + 30% MS (LMS); 30% fresh maize + 20% URS + 50% MS (HMS). Cows were individually supplemented with concentrate (1.1 kg DM/100 kg LW) and had free access to mixed roughage and water throughout the 12-week feeding trial, after a 2-week adaptation. Maize silage inclusion significantly increased daily feed intake and average daily gain (ADG) (P < 0.05). Moreover, the roughage containing 30% MS recorded the lowest feed conversion rate (7.8) and the highest final body condition score (3.43). However, LW and body measurements were not affected by the substitution (P > 0.05). Positive and significant correlations between LW and body measurements were observed. Regression analysis between chest girth (CG) and LW resulted in an equation with adjusted an R 2 value of 82.0%. The multiple regression, which included CG, body length (BL) and withers height (WH) yielded the most reliable equation (adjusted R 2 = 87.4%). The results indicate that MS can be a good alternative roughage source for feedlot culled local Yellow cows during winter in Northwest Vietnam. It is highly recommended that smallholder farmers raising non-pregnant Yellow cows use the regression equation: LW = 3.39 CG -249 for prediction of LW in the absence of weighing scales.