Performance and range use of organic broilers with access to different vegetation in outdoor areas

Outdoor range areas are an important part of the organic broiler production, and the question is how to make this area as attractive for the broilers as possible. The aim of the study was to investigate the influence­ of vegetation in outdoor range areas on performance, crop and gizzard content and range use of organic broilers. The experiment was performed on an organic form in the summer of 2015 and 2016. The outdoor range was a grass field (F) or grass field combined with a plantation (GP). There were two replicates for each type of outdoor range. Eight hundred broilers were allocated to each rep I icete. Feed intake were registered daily. In 2015, 80 broilers from each replicate were weighed at 7, 14, 28, 42, 56, 70 and 84 days ofoge, and in 20 I 6 at 28, 56 and 70 days of age. The range use was observed three times in 2015 and two times in 2016. Crop end gizzard content and composition were investigated in 12 weeks old broilers in 2015. From each range area, 2 male and 2 female broilers were killed in the morning end in the afiernoon. The average daily gain was 40.8 and 39.3 g for GP and F, respectively in 2015 for the whole growth period, and 41.9 and 40.7 g for GP end Fin 2016. The differences were statistically significant in 2015 but not in 2016. Feed intake was 125 and 133 g/day on GP and F, respectively in 2015, but feed intake per chicken or feed efficiency were not statistically different for the two types of range areas in 2015. The crop contained more material in broilers from GP than F, which was not the case for gizzard content However, the results for crop content should be interpreted with care as outdoor range, sex, and time of day interaction were observed. The crop contained mainly feed and the gizzard mainly grass. It was observed that broilers on F remained more inside the chicken house than on GP, and broilers on GP were most ofien observed to stay in the area covered with trees

Between-cow variation in the components of feed efficiency

A meta-analysis based on an individual-cow data set was conducted to investigate between-cow variations in the components and measurements of feed efficiency (FE) and to explore the associations among these components. Data were taken from 31 chamber studies, consisting of a total of 841 cow/period observations. The experimental diets were based on grass or corn silages, fresh grass, or a mixture of fresh grass and straw, with cereal grains or by-products as energy supplements, and soybean or canola meal as protein supplements. The average forage-to-concentrate ratio across all diets on a dry matter basis was 56:44. Variance component and repeatability estimates of FE measurements and components were determined using diet, period, and cow within experiment as random effects in mixed procedures of SAS (SAS Institute Inc., Cary, NC). The between-cow coefficient of variation (CV) in gross energy intake (GE; CV = 0.10) and milk energy (El) output as a proportion of GE (El/GE; CV = 0.084) were the largest among all component traits. Similarly, the highest repeatability estimates (≥0.50) were observed for these 2 components. However, the between-cow CV in digestibility (DE/GE), metabolizability [metabolizable energy (ME)/GE], methane yield (CH4E/GE), proportional urinary energy output (UE/GE), and heat production (HP/GE), as well as the efficiency of ME use for lactation (kl), were rather small. The least repeatable component of FE was UE/GE. For FE measurements, the between-cow CV in residual energy-corrected milk (RECM) was larger than for residual feed intake (RFI), suggesting a greater possibility for genetic gain in RECM than in RFI. A high DE/GE was associated with increased CH4E/GE (r = 0.24), HP/GE (r = 0.12), ME/GE (r = 0. 91), energy balance as a proportion of GE (EB/GE; r = 0.35), and kl (r = 0.10). However, no correlation between DE/GE and GE intake or UE/GE was observed. Increased proportional milk energy adjusted to zero energy balance (El(0)/GE) was associated with increases in DE/GE, ME/GE, EB/GE, and kl but decreases in UE/GE, CH4E/GE, and HP/GE, with no effect on GE intake. In conclusion, several mechanisms are involved in the observed differences in FE among dairy cows, and reducing CH4E yield (CH4E/GE) may inadvertently result in reduced GE digestibility. However, the selection of dairy cows with improved energy utilization efficiencies offers an effective approach to lower enteric CH4 emissions.202

Short communication: Variation in feed efficiency hampers use of carbon dioxide as a tracer gas in measuring methane emissions in on-farm conditions

Breeding cows for low CH4 emissions requires that the trait is variable and that it can be recorded with low cost from an adequate number of individuals and with high precision, but not necessarily with high accuracy if the trait is measured with high repeatability. The CH4:CO2 ratio in expired breath is a trait often used as a tracer with the production of CO2 predicted from body weight (BW), energy-corrected milk yield, and days of pregnancy. This approach assumes that efficiency of energy utilization for maintenance and production is constant. Data (307 cow-period observations) from 2 locations using the same setup for measuring CH4 and CO2 in respiration chambers were compiled, and observed production of CH4 and CO2 was compared with the equivalent predicted production using 2 different approaches. Carbon dioxide production was predicted using a previously reported model based on metabolic BW and energy-corrected milk production and a currently developed model based on energy requirements and the relationship between observed CO2 and heat production (models 1 and 2, respectively). Animals used were categorized (low, medium, and high efficiency) according to (1) residual feed intake and (2) residual milk production. Model 1 underestimated CH4 production by 15%, whereas model 2 overestimated CH4 by 1.4% for the whole database. Model 1 underestimated CO2 production by 2.8 and 0.9 kg/d for low- and high-efficiency cows, respectively, whereas model 2 underestimated CO2 production by 0.9 kg/d for low-efficient animals but overestimated it by 1.2 kg/d for high-efficiency cows. Efficient cows produce less heat, and consequently CO2, per unit of metabolic body weight and energy-corrected milk than inefficient cows, challenging the use of CO2 as a tracer gas. Because of biased estimates of CO2 production, the models overestimated CH4 production of high-efficiency cows by, on average, 17% relative to low-efficiency cows, respectively. Selecting low CH4-emitting cows using a CO2 tracer method can therefore favor inefficient cows over efficient cows.202

Effects of dietary inclusion of 3 Nordic brown macroalgae on enteric methane emission and productivity of dairy cows

ABSTRACT: Macroalgae are receiving increased attention as antimethanogenic feed additives for cattle, but most in vivo studies are limited to investigating effects of the red macroalgae Asparagopsis spp. Hence, this study aimed to investigate the CH4 mitigating potential of 3 brown macroalgae from the Northern Hemisphere when fed to dairy cows, and to study the effects on feed intake, milk production, feed digestibility, and animal health indicators. The experiment was conducted as a 4 × 4 Latin square design using 4 lactating rumen, duodenal, and ileal cannulated Danish Holstein dairy cows. The cows were fed a total mixed ration (TMR) without any macroalgae or the same TMR diluted with, on a dry matter basis, either 4% ensiled Saccharina latissima, 4% Ascophyllum nodosum (NOD), or 2% Sargassum muticum (MUT). Each period consisted of 14 d of adaptation, 3 d of digesta and blood sampling, and 4 d of gas exchange measurements using respiration chambers. Milk yield and dry matter intake (DMI) were recorded daily. Blood was sampled on d 13 and 16 and analyzed for health status indicators. None of the 3 species affected the CH4 emission. Moreover, milk yield and DMI were also unaffected. Total-tract digestibility of crude protein was significantly lower for NOD compared with other diets, and additionally, the NOD diet also tended to reduce total-tract digestibility of neutral detergent fiber compared with MUT. Blood biomarkers did not indicate negative effects of the dietary inclusion of macroalgae on cow health. In conclusion, none of the 3 brown macroalgae reduced CH4 emission and did not affect DMI and milk production of dairy cows, whereas negative effects on the digestibility of nutrients were observed when A. nodosum was added. None of the diets would be allowed to be fed in commercial dairy herds due to high contents of iodine, cadmium, and arsenic

Fiber digestibility and protein value of pulp silage for lactating dairy cows: Effects of wet fractionation by screw pressing of perennial ryegrass

ABSTRACT: The aim of the study was to investigate the effects of substituting silage of chopped grass with pulp silage of grass fractionated once or twice in a biorefinery using a screw press on fiber kinetics, protein value, and production of CH4 in dairy cows. Six lactating multiparous Holstein cows in mid-lactation (176 ± 93 d in milk), cannulated in the rumen, duodenum, and ileum, were used in an incomplete 6 × 4 Latin square design with a 2 × 3 factorial arrangement of treatments. Perennial ryegrass was harvested in third regrowth from the same field at early and late developmental stage (35 and 44 d of regrowth, respectively) and subjected to 1 of 3 types of processing within each developmental stage. Grass was either harvested for normal silage making (mowed, wilted, chopped, and ensiled), or harvested fresh and fractionated using a screw press. Half of the pulp from the first fractionation was ensiled, whereas the other half of the pulp was rehydrated, fractionated a second time, and pulp hereof was ensiled. The grass and pulp silages were used with concentrates (65:35 forage to concentrate ratio) to make total mixed rations (TMR) based on either silage of chopped grass (GS), pulp silage of grass fractionated once (1×P), or pulp silage of grass fractionated twice (2×P), harvested either at early (E) or late (L) developmental stage resulting in 6 different TMR treatments (EGS, E1×P, E2×P, LGS, L1×P, L2×P). The TMR were fed for ad libitum intake and samples of intestinal digesta and feces were collected for determination of digestibility. The effect of processing on ash-free neutral detergent fiber (aNDFom) concentration in silages depended on developmental stage, but showed that within each developmental stage, pulp silage of grass fractionated twice had higher aNDFom concentration than pulp silage of grass fractionated once and silage of chopped grass. The 2×P resulted in lower (14.9 ± 0.55 vs. 17.5 ± 0.54 kg/d) dry matter intake (DMI) compared with GS. The effects of processing and developmental stage interacted such that apparent total-tract aNDFom digestibility was higher (784 ± 13 vs. 715 ± 13 g/kg) for L2×P compared with LGS, whereas no difference was found between E2×P and EGS. Moreover, the protein value was higher (106 ± 5 vs. 92 ± 5 g AA digested in the small intestine/kg of DMI) for 2×P compared with GS. Unexpectedly, processing had no effect on fractional rate of digestion of digestible aNDFom or CH4 yield (L/kg of DMI), whereas feeding forages harvested at early compared with late developmental stage resulted in lower CH4 yield. Feeding pulp silage of grass fractionated once generally yielded results intermediate to cows fed silage of chopped grass and pulp silage of grass fractionated twice. This study showed that pulp silage of fractionated grass could serve as feed for dairy cows because the fiber digestibility and protein value improved, but further research investigating effects of physical processing of forage on fiber kinetics is required

Ranking cows’ methane emissions under commercial conditions with sniffers versus respiration chambers

This study assessed the ranking of dairy cows using individual-level correlations for methane (CH 4 ) emission on-farm using sniffers and in respiration chambers. In total 20 lactating dairy cows, ten Holstein and ten Jerseys were recorded using sniffers installed in milking robots for three weeks of lactation and subsequently in respiration chambers (RC) where they were each recorded on three occasions within the RC. Bivariate linear mixed models were used to determine the individual-level correlations (r I ) between sniffer and RC phenotypes as proxies for genetic correlations. Despite differences in feeding and management, the predicted CH 4 production from sniffers correlated highly with RC CH 4 production r I = 0.77 ± 0.18 and CH 4 breath concentration correlated nearly as well with RC CH 4 production r I = 0.75 ± 0.20. These correlations between sniffers on-farm and RC demonstrate the potential of sniffers measurements as large-scale indicator traits for CH 4 emissions in dairy cattle. </p

Effect of dietary nitrate level on enteric methane production, hydrogen emission, rumen fermentation, and nutrient digestibility in dairy cows

AbstractNitrate may lower methane production in ruminants by competing with methanogenesis for available hydrogen in the rumen. This study evaluated the effect of 4 levels of dietary nitrate addition on enteric methane production, hydrogen emission, feed intake, rumen fermentation, nutrient digestibility, microbial protein synthesis, and blood methemoglobin. In a 4×4 Latin square design 4 lactating Danish Holstein dairy cows fitted with rumen, duodenal, and ileal cannulas were assigned to 4 calcium ammonium nitrate addition levels: control, low, medium, and high [0, 5.3, 13.6, and 21.1g of nitrate/kg of dry matter (DM), respectively]. Diets were made isonitrogenous by replacing urea. Cows were fed ad libitum and, after a 6-d period of gradual introduction of nitrate, adapted to the corn-silage-based total mixed ration (forage:concentrate ratio 50:50 on DM basis) for 16d before sampling. Digesta content from duodenum, ileum, and feces, and rumen liquid were collected, after which methane production and hydrogen emissions were measured in respiration chambers. Methane production [L/kg of dry matter intake (DMI)] linearly decreased with increasing nitrate concentrations compared with the control, corresponding to a reduction of 6, 13, and 23% for the low, medium, and high diets, respectively. Methane production was lowered with apparent efficiencies (measured methane reduction relative to potential methane reduction) of 82.3, 71.9, and 79.4% for the low, medium, and high diets, respectively. Addition of nitrate increased hydrogen emissions (L/kg of DMI) quadratically by a factor of 2.5, 3.4, and 3.0 (as L/kg of DMI) for the low, medium, and high diets, respectively, compared with the control. Blood methemoglobin levels and nitrate concentrations in milk and urine increased with increasing nitrate intake, but did not constitute a threat for animal health and human food safety. Microbial crude protein synthesis and efficiency were unaffected. Total volatile fatty acid concentration and molar proportions of acetate, butyrate, and propionate were unaffected, whereas molar proportions of formate increased. Milk yield, milk composition, DMI and digestibility of DM, organic matter, crude protein, and neutral detergent fiber in rumen, small intestine, hindgut, and total tract were unaffected by addition of nitrate. In conclusion, nitrate lowered methane production linearly with minor effects on rumen fermentation and no effects on nutrient digestibility