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Thirty-one strains of propionic acid bacteria were screened for their effects on methane production and volatile fatty acid concentrations using in vitro assays of rumen fluid from Norwegian dairy cows and a grass silage–concentrate mixture as substrate. Nine of 31 strains were further analysed for effects on substrate degradation. Propionic acid bacteria led to reductions of up to 20% in methane production. Seven strains stimulated volatile fatty acid production, and in their presence in vitro substrate degradation tended to increase (P

Dairy milk samples from 37 milk tours in 15 areas of Norway were collected during indoor feeding or on pasture in 2008 and analyzed with respect to 6 major elements (Ca, P, K, S, Na, Mg) and 28 trace elements (As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Fe, I, La, Li, Mn, Mo, Nd, Pb, Rb, Sb, Se, Sm, Sr, V, Y, Yb and Zn). Surprisingly, the least-square means of major and trace elements in milk did not vary much from one region to another. The concentration levels of iodine, copper, manganese and lithium in milk from the northern region were higher compared with milk from other regions. Milk from the south was enriched with respect to selenium, yttrium, cerium and bismuth, while milk from the western region was enriched with respect to rubidium.

The main objective of this study was to elucidate the potential for prediction of enteric methane (CH4) emissions from dairy cows by using predicted rumen plus hindgut digested (fermented nutrients) and total tract digested nutrients (by using NorFor) as input variables. Twenty-one experiments (78 dietary treatments) were collected. The data-set was used to develop prediction models and to test their and extant models ability to predict enteric CH4 emissions. Models were compared based on mean squared prediction error and concordance correlation coefficient (CCC) analysis. Fermented nutrients did not predict enteric CH4 emissions adequately (CCC < 0.420). Including total digested (td) nutrients in the model [CH4 (MJ/d) = −2.13 + 1.64 tdOM (kg/d) −9.74 tdFat (kg/d) + 1.64 tdNDF (kg/d)] predicted enteric CH4 emissions more precisely (CCC = 0.733), and showed an improvement in the prediction of enteric CH4 emissions over the extant models tested.

Sixteen strains of propionibacteria were inoculated into in vitro ruminal incubations to evaluate their potential to reduce methane (CH4) production from concentrate and forage diets. Propionibacte...

Globally, methane emissions account for 40–45% of greenhouse gas emissions from ruminant livestock, with over 90% of these emissions arising from enteric fermentation. Consequently, enteric CH4 emi...

To evaluate the iodine (I) level in Norwegian milk, the I concentration was determined in 104 dairy tanker milk samples collected from 19 milk tours in different areas of Norway, throughout the year 2008. The I concentration in milk from indoor feeding was 122 µg L−1 and higher than in milk from the summer season, being 92 µg L−1. The weighted average mean I concentration throughout the year was 114 µg L−1 milk. The results showed that the I concentration in milk from the winter season 2008 has been reduced to nearly the half during the last decade, from 232 µg I L−1 in milk collected in the winter season in 2000. The I concentration in milk from the summer season is at the same level as a decade ago. The reason for the reduction in I in milk produced during the winter season is not known.

The main purpose of this study was to examine sources of variation in free amino acids (FAA) in the rumen and their relative contribution to the total duodenal amino acid supply. Six cannulated lactating dairy cows fed three concentrate mixtures differing in ruminally degradable intake protein (101, 114 and 134 g kg-1 dry matter) at two levels of intake (19.3 vs 9.8 kg dry matter day-1

Six dairy cows fitted with rumen and duodenal cannulae were assigned to two replicated 3×3 Latin squares in order to examine amino acid (AA) composition of rumen liquid‐associated bacteria (LAB) and solid‐adherent bacteria (SAB). Treatments comprised three concentrate mixtures differing in the amount of rumen degradable intake protein (DIP): 13.4, 11.4 and 10.1% of DM, respectively. Measurements were taken in early lactation, at high feeding level (19.7 kg DM day−1), and repeated at late lactation (10 kg DM day−1) with the same animals and diets. The SAB contained more AA than LAB (P < 0.05), and differences in AA profiles between LAB and SAB were observed for 9 out of 17 AA studied. Feeding level affected only four AA. Increased levels of DIP in the concentrate mixtures increased the content of AA in the bacteria (P < 0.05). Addition of formaldehyde to the ruminai samples prior to bacterial isolation reduced the total AA content by 11%, on average.

The effect of rumen incubation on the true indigestibility of feed protein in the digestive tract (TIFP) was studied for 10 concentrates. Only fish meal and soybean meal showed a constant TIFP independent of rumen incubation time or extent of rumen protein degradation. For the other feedstuffs, TIFP decreased to various degrees at increased ruminal protein degradation. For extracted rapeseed meal, maize gluten meal and guar meal, however, TIFP measured without pre-incubation in the rumen was also satisfactory as a basis for predicting the true digestibility of rumen undegraded feed protein in the intestine (TDRUP) for practical purposes. In contrast, TIFP for predicting TDRUP for peas, rapeseeds, lupin seeds, barley and oats should be determined on feed samples after rumen incubation.