This paper describes analysis by near infrared reflectance spectroscopy (NIRS) and demonstrates the capacity of this technology to provide rapid, low cost and accurate estimates of feed composition. The need for an extensive database against which the instruments is calibrated and the importance of good wet chemistry backup to NIRS are emphasised, together with some of the diverse uses for NIRS in research and agriculture. Examples are given of contrasting analyses for quality of maize silage and pastures. NIRS prediction of pasture, silage and supplement composition can be used in conjunction with a ration balancing model developed for the New Zealand dairy industry, allowing farmers to formulate diets able to meet desired levels of production. Keywords: dairy, feed quality, forage analysis, NIRS, nutrition

Methane emissions and digestive physiology of non-lactating dairy cows fed pasture forage. Can. J. Anim. Sci. 87: 601-613. The objective of this study was to identify intake and digestion characteristic(s) responsible for variation in methane (CH 4 ) emissions from non-lactating cows fed pasture forage. Nine Friesian × Jersey cows ranked low, medium or high CH 4 emitters [group means 15.3, 19.2 and 24.8 g kg -1 dry matter intake (DMI), respectively; P = 0.015] were selected from a herd of 302 lactating cows. The selected cows were dried-off, rumen-fistulated, and fed indoors on fresh pasture forage at 0700 and 1700. Voluntary feed intake (VFI), feeding behaviour and intake rates (IR) were measured over 5 d. Feed allowance was reduced to 90% of VFI for measurement of CH 4 emissions and rumen fermentation and digestion kinetics parameters. Although some variation in CH 4 yield remained among the animals (26.4 ± 3.6 g kg -1 DMI), the previous ranking of cows during lactation was no longer evident during this study (P = 0.41). The change in CH 4 yields may have resulted from lower feed intakes of lower quality pasture compared with grazing. Regression analysis showed that absolute CH 4 emission (g d -1 ) was best described by DMI and rumen acetate concentration (ACE) before the PM feeding (ACE 1700) (R 2 = 0.88), whereas CH 4 yield (g kg -1 DMI) was mainly a function of ACE 1700 h alone (R 2 = 0.84). We suggest that large animal-to-animal variations in CH 4 yield are most likely associated with high intakes and concomitant effects of salivation and rumen digestion and passage.

Methane (CH4) production from ruminant digestion has a significant impact on the New Zealand greenhouse gas (GHG) inventory and represents a loss of about 10% of metabolisable energy (ME) intake. Previous trials with sheep and cattle have demonstrated significantly lower methane losses per unit feed intake from legumes compared to grass dominant pasture. Most trials have compared forages fed as sole diets but white clover (Trifolium repens) is usually fed with perennial ryegrass (Lolium perenne) as a mixed pasture, as it complements ryegrass for animal production. An indoor feeding trial was conducted in December 2003 with thirty-two Holstein-Friesian dairy cows in mid-lactation to determine effects of increasing proportions of white clover on methane emissions and cow performance. Cows were housed indoors and fed perennial ryegrass with 0, 15, 30 or 60% white clover ad libitum on a dry matter (DM) basis. Increasing proportions of white clover resulted in linear increases in dry matter intakes (DMI) and reductions in methane per kg DM eaten, although the extent to which CH4 production/kg DMI was lowered was less than anticipated from previous measurements from sheep fed white clover as a sole diet. DMI of cows fed 60% white clover was 20.5 vs. 15.6 kg DM/cow/day for 100% perennial ryegrass (P

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