| 1. |
- Cabezas Garcia, Edward Hernando, et al.
(författare)
-
Between-cow variation in digestion and rumen fermentation variables associated with methane production
- 2017
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 100, s. 4409-4424
-
Tidskriftsartikel (refereegranskat)abstract
- A meta-analysis based on an individual-cow data set was conducted to investigate the effects of between-cow variation and related animal variables on predicted CH4 emissions from dairy cows. Data were taken from 40 change-over studies consisting of a total of 637 cow/period observations. Animal production and rumen fermentation characteristics were measured for 154 diets in 40 studies; diet digestibility was measured for 135 diets in 34 studies, and ruminal digestion kinetics was measured for 56 diets in 15 studies. The experimental diets were based on grass silage, with cereal grains or by-products as energy supplements, and soybean or canola meal as protein supplements. Average forage:concentrate ratio across all diets on a dry matter basis was 59:41. Methane production was predicted from apparently fermented substrate using stoichiometric principles. Data were analyzed by mixed-model regression using diet and period within experiment as random effects, thereby allowing the effect of experiment, diet, and period to be excluded. Dry matter intake and milk yield were more repeatable experimental measures than rumen fermentation, nutrient outflow, diet digestibility, or estimated CH4 yield. Between-cow coefficient of variation (CV) was 0.010 for stoichiometric CH4 per mol of volatile fatty acids and 0.067 for predicted CH4 yield (CH4/dry matter intake). Organic matter digestibility (OMD) also displayed little between-cow variation (CV = 0.013), indicating that between-cow variation in diet digestibility and rumen fermentation pattern do not markedly contribute to between cow-variation in CH4 yield. Digesta passage rate was much more variable (CV = 0.08) between cows than OMD or rumen fermentation pattern. Increased digesta passage rate is associated with improved energetic efficiency of microbial N synthesis, which partitions fermented substrate from volatile fatty acids and gases to microbial cells that are more reduced than fermented carbohydrates. Positive relationships were observed between CH4 per mol of volatile fatty acids versus OMD and rumen ammonia N concentration versus OMD; and negative relationships between the efficiency of microbial N synthesis versus OMD and digesta passage rate versus OMD, suggesting that the effects of these variables on CH4 yield were additive. It can be concluded that variations in OMD and efficiency in microbial N synthesis resulting from variations in digesta passage contribute more to between-animal variation in CH4 emissions than rumen fermentation pattern.
|
|
| 2. |
- Cabezas Garcia, Edward Hernando, et al.
(författare)
-
Effects of replacement of late-harvested grass silage and barley with early-harvested silage on milk production and methane emissions
- 2017
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 100, s. 5228-5240
-
Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the effects of gradual replacement of a mixture of late-cut grass silage (LS) and barley with early-cut grass silage (ES) on milk production, CH4 emissions, and N utilization in Swedish Red cows. Two grass silages were prepared from the same primary growth of timothy grass sward but harvested 2 wk apart [11.0 and 9.7 MJ of metabolizable energy/kg of dry matter (DM)]. Four diets, fed as a total mixed ration, were formulated to meet the metabolizable energy and protein requirements of 35 kg of energy-corrected milk (ECM) by gradually replacing a mixture of LS and barley with ES (0, 33, 67, and 100% of the forage component of the diet), whereas the proportion of barley decreased from 47.2 to 26.6% of diet DM. Expeller canola meal was used as a protein supplement. Sixteen Swedish Red cows were used in 4 replicated 4 x 4 Latin squares. Cows were offered diets ad libitum and milked twice daily. Each period of 28 d comprised 14 d of diet adaptation followed by 14 d of data collection. Intake and milk yield were recorded daily, and milk samples were collected on d 19 to 21 and d 26 to 28 of each period. Diet digestibility was determined by grab sampling using indigestible neutral detergent fiber as an internal marker. Gas emissions were measured using the Green Feed system (C-Lock Inc., Rapid City, SD). Dry matter intake (DMI) linearly decreased from 22.6 to 19.3 kg/d as the proportion of ES increased in the diet. The ECM yield did not differ among treatments, but milk protein yield decreased with increasing proportion of ES in the diet. Because of reduced DMI with increasing ES, feed efficiency (ECM/DMI) improved with an increased proportion of ES in the diet. Nitrogen efficiency (milk N/N intake) did not change despite a linear increase in milk urea N concentration from 9.7 (LS alone) to 11.9 mg/dL (ES alone) with graded replacement of LS and barley by ES in the diet. Lower DMI responses in ES diets were partly compensated for by increased organic matter digestibility (656 g/kg of DM for LS alone; 715 g/kg of DM for ES alone) related to improved forage digestibility at early harvesting. Total CH4 emissions and CH4 intensity (CH4/ECM) were not influenced by diet, but CH4 yield (CH4/DMI) increased linearly from 19.5 to 23.0 g/kg of DMI with greater inclusion of ES in the diet. In conclusion, replacing LS and barley with ES improved the conversion of feed to milk without increasing CH4 emissions or compromising N efficiency.
|
|
| 3. |
- Cabezas Garcia, Edward Hernando, et al.
(författare)
-
Effects of replacement of late-harvested grass silage and barley with early-harvested silage on ruminal digestion efficiency in lactating dairy cows
- 2018
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 101, s. 1177-1189
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this experiment was to quantify the effects of graded replacement of late-harvested grass silage and barley with early-harvested silage on nutrient digestion and rumen fermentation. Four experimental diets were fed to 4 multiparous rumen-cannulated Nordic Red cows in 4 x 4 Latin square design with 21-d periods. Dietary treatments consisted of late-cut grass silage (LS) and rolled barley, which was gradually replaced with early-cut grass silage [ES; 0, 33, 67, and 100% of the forage component (ES + LS) of the diet]. With increased proportion of ES in the diet, the proportion of barley decreased from 47.2 to 26.6% on a dry matter basis. Early-and late-cut silages were harvested at 2-wk intervals (predicted concentrations of metabolizable energy 11.0 and 9.7 MJ/kg of dry matter). The 4 diets were formulated to support the same milk production. Nutrient flows were quantified using omasal sampling technique applying the triple-marker method (Cr, Yb, and indigestible neutral detergent fiber) and N-15 as a microbial marker. Feed intake decreased with graded replacement of LS and barley with ES, but milk production was not influenced by diet. Digestibility of nutrients improved with graded addition of ES in the diet with the greatest difference observed in digestibility of neutral detergent fiber (NDF) and potentially digestible NDF (pdNDF). The results suggested that improved cell wall digestibility with graded level of ES in the diet was partly related to higher intrinsic digestibility of ES than LS, and partly due to negative associative effects with an increased proportion of LS and barley in the diet. Efficiency of microbial N synthesis was not influenced by the diet, but ruminal protein degradability increased with ES in the diet. Rumen fermentation pattern was not affected by the diet despite large difference in the profile of dietary carbohydrates. Rumen pool size of NDF and pdNDF, and ruminal turnover time of NDF decreased with graded addition of ES in the diet, whereas digestion rate of pdNDF improved. The results of this study indicate that increased CH4 yield in a parallel production study with graded addition of ES in the diet were more related to greater ruminal and total digestibility of organic matter than to the changes in rumen fermentation pattern.
|
|
| 4. |
- Cabezas Garcia, Edward Hernando, et al.
(författare)
-
Fibre digestion potential in sugarcane across the harvesting window
- 2014
-
Ingår i: Grass and Forage Science. - : Wiley. - 0142-5242 .- 1365-2494. ; 69, s. 176-181
-
Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study were to determine the proportion of indigestible neutral detergent fibre (iNDF) in the neutral detergent fibre (NDF) fraction of sugarcane, to estimate changes in NDF digestibility (NDFD) during the harvesting window and to predict sugarcane digestibility based on its fibre fractions. Whole plants of the IAC86-2480 and IAC93-3046 varieties were collected during the harvesting windows in 2007 and 2009, respectively. The in vitro true dry matter digestibility (IVTDMD) and fibre contents (NDF, iNDF, acid detergent fibre) were determined by near infrared reflectance spectroscopy (NIRS). The NDFD and potentially digestible NDF digestibility (pdNDFD) were estimated, and the fractional digestion rate of pdNDF was calculated. There was no relationship between growing days and iNDF as a proportion of NDF (P = 0.28) or with the fractional digestion rate of pdNDF (P = 0.30). Therefore, NDFD (mean = 335 g kg(-1)) and pdNDFD (mean = 657 g kg(-1)) remained almost constant during the harvesting window (P = 0.70 and P = 0.32 respectively). Acid detergent fibre and NDF were the best predictors of sugarcane dry matter (DM) digestibility. In conclusion, NDFD seems to be unchanged during crop growth. The point at which to harvest sugarcane as a forage source should therefore be decided based on NDF concentration, which is greatly influenced by sucrose accumulation.
|
|
| 5. |
- Cabezas Garcia, Edward Hernando, et al.
(författare)
-
In Vitro Incubations Do Not Reflect In Vivo Differences Based on Ranking of Low and High Methane Emitters in Dairy Cows
- 2021
-
Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- This study evaluated if ranking dairy cows as low and high CH4 emitters using the GreenFeed system (GF) can be replicated in in vitro conditions using an automated gas system and its possible implications in terms of fermentation balance. Seven pairs of low and high emitters fed the same diet were selected on the basis of residual CH4 production, and rumen fluid taken from each pair incubated separately in the in vitro gas production system. In total, seven in vitro incubations were performed with inoculums taken from low and high CH4 emitting cows incubated in two substrates differing in forage-to-concentrate proportion, each without or with the addition of cashew nutshell liquid (CNSL) as an inhibitor of CH4 production. Except for the aimed differences in CH4 production, no statistical differences were detected among groups of low and high emitters either in in vivo animal performance or rumen fermentation profile prior to the in vitro incubations. The effect of in vivo ranking was poorly replicated in in vitro conditions after 48 h of anaerobic fermentation. Instead, the effects of diet and CNSL were more consistent. The inclusion of 50% barley in the diet (SB) increased both asymptotic gas production by 17.3% and predicted in vivo CH4 by 26.2%, when compared to 100% grass silage (S) substrate, respectively. The SB diet produced on average more propionate (+28 mmol/mol) and consequently less acetate compared to the S diet. Irrespective of CH4 emitter group, CNSL decreased predicted in vivo CH4 (26.7 vs. 11.1 mL/ g of dry matter; DM) and stoichiometric CH4 (CH4VFA; 304 vs. 235 moles/mol VFA), with these being also reflected in decreased total gas production per unit of volatile fatty acids (VFA). Microbial structure was assessed on rumen fluid sampled prior to in vitro incubation, by sequencing of the V4 region of 16S rRNA gene. Principal coordinate analysis (PCoA) on operational taxonomic unit (OTU) did not show any differences between groups. Some differences appeared of relative abundance between groups in some specific OTUs mainly related to Prevotella. Genus Methanobrevibacter represented 93.7 ± 3.33% of the archaeal sequences. There were no clear differences between groups in relative abundance of Methanobrevibacter.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Danielsson, Rebecca, et al.
(författare)
-
Evaluation of a gas in vitro system for predicting methane production in vivo
- 2017
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 100, s. 8881-8894
-
Tidskriftsartikel (refereegranskat)abstract
- Methane production from ruminant livestock varies with the diet as a result of factors such as dry matter intake, diet composition, and digestibility. To estimate the effect of dietary composition and feed additives, CH4 production can be measured in vitro as a first step because large numbers of samples can be incubated and analyzed at the same time. This study evaluated a recently developed in vitro method for prediction of in vivo CH4 production by examining the relationship between predicted and observed CH4 production values. A total of 49 different diets (observations), used in previous 13 in vivo studies, were selected to include diets varying in nutrient composition. Methane production was measured in all in vivo studies by respiration chambers or the GreenFeed system (C-Lock Inc., Rapid City, SD). Overall, the in vitro system predicted CH4 production well (R-2 = 0.96), but the values obtained were slightly underestimated compared with observed in vivo values (mean 399 L/d compared with 418 L/d: root mean square prediction error = 51.6 L/d or 12.3% of observed mean). Further analysis of the effect on residuals showed no significant relationship between CH4 production and most factors known to affect CH4 production such as dry matter intake, digestibility, and dietary concentrations of fat and starch. However, some factors included in the model were not well predicted by the system, with residuals negatively related to neutral detergent fiber concentration and positively related to concentrate proportion. The in vitro system can thus be useful for screening diets and evaluation of feed additives as a first step that can be best interpreted when feeding cows at maintenance level.
|
|
| 9. |
- De Oliveira Franco, Marcia, et al.
(författare)
-
In vitro evaluation of agro-industrial by-products replacing soybean meal in two different basal diets for ruminants
- 2017
-
Ingår i: Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård. - 0347-9838. ; , s. 54-59
-
Konferensbidrag (refereegranskat)abstract
- Large number of by-products from the agricultural industry can potentially be used as protein sources in diets to dairy cows. The increasing demand for alternative dietary protein supplements in ruminant production systems is due to a growing requirement for a more sustainable food production from the livestock industry. However, use of agro-industrial byproducts in diets to dairy cows and beef cattle have to be efficient in terms of nutrient utilization, be complementary to basal feed ingredients and not impair production. Since in vivo studies are very expensive and laborious, using an in vitro gas production technique enables identification of by-products which can efficiently replace conventional ingredients. Recently, there has been great progress in the development of the automated gas in vitro technique, which enables treatment evaluation of ruminal fermentation profiles, diet digestion rates (Huhtanen et al., 2008), methane (CH4) production (Ramin and Huhtanen, 2012) and estimation of utilizable crude protein (uCP; Edmunds et al., 2012). The aim of this study was to evaluate effects of levels of agro-industrial by-products replacing soybean meal in diets based on silage and barley or beet fibre on neutral detergent fibre (NDF) digestibility, true organic matter (OM) digestibility, uCP, fermentation parameters and CH4 production in vitro.
|
|
| 10. |
|
|
