Effects of replacement of barley with oats on milk fatty acid composition in dairy cows fed grass silage-based diets.

This study consists of milk fatty acid (FA) data collected during 2 in vivo experiments. For this study, 8 cows from each experiment were included in a replicated 4 × 4 Latin square design. At the start of experiment 1 (Exp1) cows were at (mean ± standard deviation) 87 ± 34.6 d in milk, 625 ± 85.0 kg of body weight, and 32.1 ± 4.17 kg/d milk yield and at the start of experiment 2 (Exp2) cows were at 74 ± 18.2 d in milk, 629 ± 87.0 kg of body weight, and 37.0 ± 3.2 kg/d milk yield. In Exp1, we examined the effects of gradual replacement of barley with hulled oats (oats with hulls) on milk FA composition. The basal diet was grass silage and rapeseed meal (58 and 10% of diet DM, respectively), and the 4 grain supplements were formulated so that barley was gradually replaced by hulled oats at levels of 0, 33, 67, and 100% on dry matter basis. In Exp2, we examined (1) the effects of replacing barley with both hulled and dehulled oats (oats without hulls) and (2) the effects of gradual replacement of hulled oats with dehulled oats on milk FA composition. The basal diet was grass silage and rapeseed meal (60 and 10% of diet DM, respectively), and the 4 pelleted experimental concentrates were barley, hulled oats, a 50:50 mixture of hulled and dehulled oats, and dehulled oats on dry matter basis. In Exp1, gradual replacement of barley with hulled oats decreased relative proportions of 14:0, 16:0, and total saturated FA (SFA) in milk fat linearly, whereas proportions of 18:0, 18:1, total monounsaturated FA, and total cis unsaturated FA increased linearly. Transfer efficiency of total C18 decreased linearly when barley was replaced by hulled oats in Exp1. In Exp2, relative proportions of 14:0, 16:0, and total SFA were lower, whereas proportions of 18:0, 18:1, monounsaturated FA, and cis unsaturated FA were higher in milk from cows fed the oat diets than in milk from cows fed the barley diet. Moreover, in Exp2, gradual replacement of hulled oats with dehulled oats slightly decreased the relative proportion of 14:0 in milk fat but did not affect the proportions of 16:0, 18:0, 18:1, total SFA, monounsaturated FA, trans FA, or polyunsaturated FA. In Exp2, transfer efficiency of total C18 was lower when cows were fed the oat diets than when fed the barley diet and decreased linearly when hulled oats were replaced with dehulled oats. Predictions of daily CH4 emissions (g/d) using the on-farm available variables energy-corrected milk yield and body weight were not markedly improved by including milk concentrations of individual milk FA in prediction equations. In conclusion, replacement of barley with oats as a concentrate supplement for dairy cows fed a grass silage-based diet could offer a practical strategy to change the FA composition of milk to be more in accordance with international dietary guidelines regarding consumption of SFA.

Replacement of barley with oats and dehulled oats: Effects on milk production, enteric methane emissions, and energy utilization in dairy cows fed a grass silage-based diet.

Sixteen Nordic Red dairy cows, at 80 ± 4.6 d in milk and with an average body weight of 624 ± 91.8 kg, were used in a replicated 4 × 4 Latin square design to investigate the effects of different concentrate supplements on milk production, enteric CH4 emissions, ruminal fermentation, digestibility, and energy utilization. The cows were blocked into 4 groups based on parity and milk yield and randomly assigned to 1 of 4 experimental concentrates: (1) barley, (2) hulled oats, (3) an oat mixture consisting of hulled and dehulled oats, 50:50 on dry matter basis, and (4) dehulled oats; canola meal was a protein supplement in all 4 concentrates. The cows were fed grass silage and experimental concentrate (forage-to-concentrate ratio 60:40 on dry matter basis) ad libitum. To compare the effects of barley and oats, the barley diet was compared with the overall mean of the hulled oat, oat mixture, and dehulled oat diets. To investigate the effects of gradual replacement of hulled oats with dehulled oats, linear and quadratic contrasts were specified. Milk and energy-corrected milk (ECM) yield were higher on the oat diets compared with the barley diet but were not affected by the type of oats. Concentrations of milk constituents were not affected by grain species or type of oats, except for protein concentration, which was lower on the oat diets than on the barley diet. Feeding the oat diets led to higher milk protein yield and higher milk urea N concentrations. Feed efficiency tended to be higher on the oat diets, and linearly increased with increased inclusion of dehulled oats. Methane emissions (g/d) and CH4 yield (g/kg of dry matter intake) were unaffected by grain species but increased linearly with increasing inclusion of dehulled oats in the diet. Because of higher ECM yield, CH4 intensity (g/kg of ECM) was on average 5.7% lower from cows on the oat diets than on the barley diet. Ruminal fermentation was not affected by dietary treatment. Total-tract apparent digestibility of organic matter, crude protein, and neutral detergent fiber was unaffected by grain species but linearly increased with increasing inclusion of dehulled oats. Gross energy content was higher on the oat diets and linearly increased with increasing inclusion of dehulled oats. Feeding the oat diets led to a lower ratio of CH4 energy to gross energy intake, greater milk energy and heat production but no change in energy balance. Gradual replacement of hulled oats with dehulled oats linearly increased gross energy digestibility, CH4 energy, metabolizable energy intake, heat production, and energy balance. We observed no effect of dietary treatment on efficiency of metabolizable energy use for lactation. In conclusion, replacing barley with any type of oats increased milk and ECM yield, which led to a 5.7% decrease in CH4 intensity. In addition, dehulling of oats before feeding is unnecessary because it did not significantly improve production performance of dairy cows in positive energy balance.

The effects of gradual replacement of barley with oats on enteric methane emissions, rumen fermentation, milk production, and energy utilization in dairy cows.

This study evaluated the effects of gradual replacement of barley with oats on enteric CH4 emissions, rumen fermentation, diet digestibility, milk production, and energy utilization in dairy cows fed a grass silage-based diet. Sixteen lactating Nordic Red dairy cows received a total mixed ration [58:42 forage:concentrate on dry matter (DM) basis]. Grass silage (Phleum pratense) was the sole forage with canola meal (10% of diet DM) as a protein supplement. The effects of gradual replacement of barley with oats on DM basis were evaluated using a replicated 4 × 4 Latin square design with 21 d periods. The grain supplements (30% of diet DM) consisted of 100% barley, 67% barley and 33% oats, 33% barley and 67% oats, and 100% oats. In addition to intake, milk production, and digestibility measurements, CH4 emissions were measured by the GreenFeed system (C-Lock Inc.). The energy metabolism was estimated from the gas exchange measurements recorded by the GreenFeed unit. The last 10 d of each period were used for recordings of gas exchanges, feed intake and milk production. Dry matter intake, body weight, milk yield, and energy-corrected milk yield were not affected by gradual replacement of barley with oats in the diet. Increased inclusion of oats linearly decreased CH4 emissions from 467 to 445 g/d, and CH4 intensity from 14.7 to 14.0 g/kg energy-corrected milk. In addition, the ratio of CH4 to CO2 decreased with increasing inclusion of oats in the diet. Digestibility of organic matter, neutral detergent fiber, and potentially digestible neutral detergent fiber decreased linearly with increasing inclusion of oats. Increased inclusion of oats linearly increased fecal energy from 121 to 133 MJ/d, whereas urinary energy and heat production were not affected by dietary treatment. This resulted in a linear decrease in metabolizable energy intake. However, increased levels of oat in the diet did not significantly affect energy balance or efficiency of metabolizable energy utilization for lactation. This study concludes that barley could be replaced with oats in the diet of dairy cows fed a grass silage-based diet to mitigate CH4 emissions without having any adverse effects on productivity or energy balance. However, the effect of replacing barley with oats on CH4 emissions is dependent on the differences between barley and oats in the concentrations of indigestible neutral detergent fiber and fat.

Effects of different barley and oat varieties on methane production, digestibility, and fermentation pattern in vitro.

The objective of this in vitro study was to determine the effects of different barley and oat varieties on CH4 production, digestibility, and rumen fermentation patterns in dairy cows. Our hypothesis was that oat-based diets would decrease CH4 production compared with barley-based diets, and that CH4 production would differ between varieties within grain species. To evaluate this hypothesis, we conducted an in vitro experiment using a fully automated gas production technique, in which the total gas volume was automatically recorded by the system. The experiment consisted of triplicate 48-h incubations with 16 treatments, including 8 different varieties of each grain. The grain varieties were investigated as a mix with an early-cut grass silage (1:1 ratio of grain to silage on a dry matter basis) and mixed with buffered rumen fluid. We estimated predicted in vivo total gas production and CH4 production by applying a set of models to the gas production data obtained by the in vitro system. We also evaluated in vitro digestibility and fermentation characteristics. The variety of grain species did not affect total gas production, CH4 production, or fermentation patterns in vitro. However, in vitro-determined digestibility and pH were affected by variety of grain species. Grain species affected total gas and CH4 production: compared with barley-based diets, oat-based diets decreased total gas production and CH4 production by 8.2 and 8.9%, respectively, relative to dry matter intake. Grain species did not affect CH4 production relative to in vitro true dry matter digestibility. Oat-based diets decreased digestibility and total volatile fatty acid production, and maintained a higher pH at 48 h of incubation compared with barley-based diets. Grain species did not affect fermentation patterns, except for decreased molar proportions of valerate with oat-based diets. These results suggest that replacing barley with oats in dairy cow diets could decrease enteric CH4 production.

Characterizing Adversity of Lysosomal Accumulation in Nonclinical Toxicity Studies: Results from the 5th ESTP International Expert Workshop.

Lysosomes have a central role in cellular catabolism, trafficking, and processing of foreign particles. Accumulation of endogenous and exogenous materials in lysosomes represents a common finding in nonclinical toxicity studies. Histologically, these accumulations often lack distinctive features indicative of lysosomal or cellular dysfunction, making it difficult to consistently interpret and assign adverse dose levels. To help address this issue, the European Society of Toxicologic Pathology organized a workshop where representative types of lysosomal accumulation induced by pharmaceuticals and environmental chemicals were presented and discussed. The expert working group agreed that the diversity of lysosomal accumulations requires a case-by-case weight-of-evidence approach and outlined several factors to consider in the adversity assessment, including location and type of cell affected, lysosomal contents, severity of the accumulation, and related pathological effects as evidence of cellular or organ dysfunction. Lysosomal accumulations associated with cytotoxicity, inflammation, or fibrosis were generally considered to be adverse, while those found in isolation (without morphologic or functional consequences) were not. Workshop examples highlighted the importance of thoroughly characterizing the biological context of lysosomal effects, including mechanistic data and functional in vitro readouts if available. The information provided here should facilitate greater consistency and transparency in the interpretation of lysosomal effects.

Primary gastric histiocytic sarcoma in a dog--a case report.

A 12-year-old intact female mixed breed dog was presented for chronic, intermittent vomiting and diarrhoea. On endoscopic examination a protruding mass arising from the mucosal surface of the pyloric region was detected. Cytological and histological examination revealed an accumulation of pleomorphic round/oval phagocytic cells suggesting histiocytic origin. This was confirmed by immunohistochemistry. No extra-gastric involvement was detected on clinical examination or at necropsy. This is the first report of primary gastric histiocytic sarcoma in a dog.