R. Khiaosa-ard

Meta-analysis of the effects of essential oils and their bioactive compounds on rumen fermentation characteristics and feed efficiency in ruminants

The present study aimed at investigating the effects of essential oils and their bioactive compounds (EOBC) on rumen fermentation in vivo as well as animal performance and feed efficiency in different ruminant species, using a meta-analysis approach. Ruminant species were classified into 3 classes consisting of beef cattle, dairy cattle, and small ruminants. Two datasets (i.e., rumen fermentation and animal performance) were constructed, according to the available dependent variables within each animal class, from 28 publications (34 experiments) comprising a total of 97 dietary treatments. In addition, changes in rumen fermentation parameters relative to controls (i.e., no EOBC supplementation) of all animal classes were computed. Data were statistically analyzed within each animal class to evaluate the EOBC dose effect, taking into account variations of other variables across experiments (e.g., diet, feeding duration). The dose effect of EOBC on relative changes in fermentation parameters were analyzed across all animal classes. The primary results were that EOBC at doses <0.75 g/kg diet DM acted as a potential methane inhibitor in the rumen as a result of decreased acetate to propionate ratio. These responses were more pronounced in beef cattle (methane, P = 0.001; acetate to propionate ratio, P = 0.005) than in small ruminants (methane, P = 0.068; acetate to propionate ratio, P = 0.056) and in dairy cattle (P > 0.05), respectively. The analysis of relative changes in rumen fermentation variables suggests that EOBC affected protozoa numbers (P < 0.001) but only high doses (>0.20 g/kg DM) of EOBC had an inhibitory effect on this variable whereas lower doses promoted the number. For performance data, because numbers of observations in beef cattle and small ruminants were small, only those of dairy cattle (DMI, milk yield and milk composition, and feed efficiency) were analyzed. The results revealed no effect of EOBC dose on most parameters, except increased milk protein percentage (P< 0.001) and content (P = 0.006). It appears that EOBC supplementation can enhance rumen fermentation in such a way (i.e., decreased acetate to propionate ratio) that may favor beef production. High doses of EOBC do not necessarily modify rumen fermentation or improve animal performance and feed efficiency. Furthermore, additional attention should be paid to diet composition and supplementation period when evaluating the effects of EOBC in ruminants.

Transfer of linoleic and linolenic acid from feed to milk in cows fed isoenergetic diets differing in proportion and origin of concentrates and roughages.

The transfer of ingested alpha-linolenic acid (ALA) and linoleic acid (LA) determines the nutritional quality of milk, but the factors determining this transfer are unclear. The present experiment investigated the influence of roughage to concentrate proportions and the effect of concentrate types on milk fat composition. Respectively, six lactating dairy cows were fed one of three isoenergetic (5.4+/-0.05 MJ net energy for lactation/kg dry matter; DM) and isonitrogenous (215+/-3.5 g crude protein/kg DM) diets, consisting of ryegrass hay only (33 g fatty acids/kg DM; ALA-rich, no concentrate), maize (straw, whole maize pellets and gluten; 36 g fatty acids/kg DM; LA-rich; 560 g concentrate/kg DM), or barley (straw and grain plus soybean meal; 19 g fatty acids/kg DM; LA-rich; 540 g concentrate/kg DM). The fatty acid composition of feeds and resulting milk fat were determined by gas chromatography. The ALA concentration in milk fat was highest (P<0.001) with the hay-diet, but the proportionate transfer of ALA from diet to milk was lower (P<0.001) than with the maize- or barley-diets. The LA concentration in milk fat was highest with the maize-diet (P<0.05, compared with hay) but relative transfer rate was lower (P=0.01). The transfer rates of ALA and LA were reciprocal to the intake of individual fatty acids which thus contributed more to milk fat composition than did roughage to concentrate proportions. The amount of trans-11 18:1 in milk fat was lowest with the barley-diet (P<0.001) and depended on the sum of ALA and LA consumed. The milk fat concentration of cis-9, trans-11 18:2 (rumenic acid) was more effectively promoted by increasing dietary LA (maize) than ALA (hay). Amounts of 18:0 secreted in milk were four (maize) to seven (hay) times higher than the amounts ingested. This was suggestive of a partial inhibition of biohydrogenation in the maize-diet, possibly caused by the high dietary LA level.

Early deposition of n-3 fatty acids from tuna oil in lean and adipose tissue of fattening pigs is mainly permanent.

A total of 600 crossbred pigs, whereof 56 were randomly selected for more in-depth studies of carcass and pork quality, were employed to test different tuna oil feeding regimens. The focus was put on the efficiency to enrich lean and adipose tissue with n-3 fatty acids and the expression of adverse side-effects on performance, carcass, and pork quality. The 4 treatments were 0% tuna oil in diet (T0; control), 1% of unrefined tuna oil in diet fed from 35 to 90 kg of BW (T1), and 3% of unrefined tuna oil in diet offered during the early (35 to 60 kg of BW; T3-E) or late stage of fattening (75 to 90 kg of BW; T3-L). With this arrangement, pigs consumed equal lifetime amounts of tuna oil (approximately 1.6 kg per pig). None of the tuna oil treatments had significant effects on performance. There were no differences in carcass quality among tuna oil groups except for group T3-E where carcasses and loin chops were fatter than those of the other groups. Water-holding capacity and texture of the loin as well as firmness and melting properties of the backfat remained widely unaffected by the treatments. Tuna oil feeding resulted in a lighter, less red and less yellow backfat and was found to increase the proportion of n-3 fatty acids to total fatty acids in all treatments. This especially concerned eicosapentaenoic acid and docosahexaenoic acid, but not alpha-linolenic acid. There was also a slight increase in oleic acid, whereas n-6 fatty acids largely decreased. Feeding tuna oil during a short period at the end of fattening (T3-L) or permanently during fattening (T1) proved to be similarly efficient in increasing n-3 fatty acid content of lean and adipose tissue (to about 1.6-fold of T0). By contrast, only two-thirds of this increase was found when the same amount of tuna oil had been fed exclusively during early fattening (T3-E). The decreased efficiency in T3-E was associated with better sensory flavor, overall acceptability grading, and oxidative status. The results show that, particularly under the condition of a continuous supply, much of the n-3 fatty acids ingested in early fattening can be recovered in pork. These findings give farmers flexibility as to when and how pork can be enriched in n-3 fatty acids with fish oil.

Transient feeding of a concentrate-rich diet increases the severity of subacute ruminal acidosis in dairy cattle.

The objective of this study was to investigate the effect of the pattern of concentrate-rich feeding on subacute ruminal acidosis (SARA), its severity, and the corresponding changes in VFA concentration. Eight rumen-cannulated Holstein cows were assigned to a 2 × 2 crossover design with 2 SARA challenge models and 2 experimental runs ( = 8 per treatment). Each run lasted for 40 d, consisting of a 6-d baseline, a 6-d gradual grain adaptation, and a 28-d SARA challenge period. The 2 SARA challenge models were transient (TRA) and persistent (PER) SARA. Initially, all cows were subjected to a forage-only diet (baseline) and gradually switched to 60% concentrate (DM basis). Then, cows in the PER model were continuously challenged for 28 d, whereas cows in the TRA model had a 7-d break from the SARA diet and were fed the forage-only diet after the first 7 d of SARA challenge. Thereafter, the TRA cows were rechallenged with the SARA diet. Wireless ruminal pH sensors were used to obtain ruminal pH profiles and temperature over the experimental period. For the determination of VFA, free ruminal liquid (FRL) and particle-associated ruminal liquid (PARL) were collected once for the baseline and twice (d 20 and 40 for the PER model) or 3 times (d 13, 30, and 40 for the TRA model) during SARA, each time at 0, 4, and 8 h after the morning feeding. Cows in both models experienced SARA albeit with day-to-day variation. From the start until the first 7-d SARA, cows of both models had similar pH profiles, but during the rechallenge, SARA was more severe in the TRA model than in the PER model based on lower daily mean ruminal pH (5.93 vs. 6.15; SEM 0.058) and double the amount of time at pH < 5.8 (497 vs. 278 min; SEM 68.61, < 0.05). Mean ruminal temperature was raised during SARA compared with the baseline (38.9 vs. 38.7°C; SEM 0.057, < 0.001). Concentrations of VFA increased with increasing time after feeding ( < 0.001). In general, SARA challenge (d 40 vs. the baseline), but not the challenge model, altered VFA concentrations and profile of both FRL and PARL by increasing the amounts of propionate and butyrate, whereas total VFA concentration was less affected. Proportions of VFA shifted over the duration of SARA challenge with more propionate but less acetate and butyrate proportions with advancing days of SARA challenge, leading to the values of the last SARA day being different from the earlier days ( < 0.05). In conclusion, the TRA condition led to the higher severity of SARA, but factors beyond feed intake and VFA alterations seemed to play a role.

Evidence of In Vivo Absorption of Lactate and Modulation of Short Chain Fatty Acid Absorption from the Reticulorumen of Non-Lactating Cattle Fed High Concentrate Diets

Short-chain fatty acids (SCFAs) and lactate are endproducts of rumen fermentation and important energy sources for the host ruminant. Because their rapid accumulation results in ruminal acidosis, enhancement of the absorption of SCFA and lactate across reticuloruminal wall is instrumental in increasing energy supply and preventing ruminal acidosis in cattle. This study investigated whether the reticuloruminal absorption of SCFAs and lactate was altered by different strategies of high concentrate feeding. Eight rumen-cannulated, non-lactating Holstein cows were fed a forage-only diet (baseline) and then gradually adapted over 6 d to a 60% concentrate level. Thereafter, this concentrate-rich diet was fed for 4 wk either continuously (Con; n = 8) or interruptedly (Int; n = 8). Absorption of SCFAs and lactate was determined in vivo from the experimental buffer introduced into the washed reticulorumen. The buffer contained acetate, propionate, butyrate and lactate at a concentration of 60, 30, 10 and 5 mmol/L, respectively and Cr-EDTA as a marker for correcting ruminal water fluxes. The reticuloruminal absorption after 35 and 65 min of buffer incubation was measured at the baseline, after 1 wk of 60% concentrate feeding in the interrupted model (Int-1) and after 4 wk of concentrate feeding in both feeding models (Int-4 and Con-4). Data showed that the absorption rates of individual and total SCFAs during the first 35 min of incubation of Con-4 were highest (~1.7 times compared to baseline), while Int-1 and Int-4 were similar to respective baseline. Lactate was not absorbed during forage-only baseline and 1-wk concentrate feeding, but after 4-wk feeding of concentrates in both models. In conclusion, SCFAs absorption across the reticulorumen of non-lactating cattle was enhanced by the 4-wk continuous concentrate feeding, which seems to be more advantageous in terms of rumen acidosis prevention compared to the interrupted feeding model. The study provides evidence of lactate absorption across the reticulorumen of non-lactating cattle after both continuous and interrupted 4-wk concentrate feeding.

Intramammary infusion of Escherichia coli lipopolysaccharide negatively affects feed intake, chewing, and clinical variables, but some effects are stronger in cows experiencing subacute rumen acidosis

Feeding high-grain diets increases the risk of subacute rumen acidosis (SARA) and adversely affects rumen health. This condition might impair the responsiveness of cows when they are exposed to external infectious stimuli such as lipopolysaccharide (LPS). The main objective of this study was to evaluate various responses to intramammary LPS infusion in healthy dairy cows and those experimentally subjected to SARA. Eighteen early-lactating Simmental cows were subjected to SARA (n = 12) or control (CON; n = 6) feeding conditions. Cows of the control group received a diet containing 40% concentrates (DM basis) throughout the experiment. The intermittent SARA feeding regimen consisted in feeding the cows a ration with 60% concentrate (DM basis) for 32 d, consisting of a first SARA induction for 8 d, switched to the CON diet for 7 d, and re-induction during the last 17 d. On d 30 of the experiment, 6 SARA (SARA-LPS) and 6 CON (CON-LPS) cows were intramammary challenged once with a single dose of 50 μg of LPS from Escherichia coli (O26:B6), whereas the other 6 SARA cows (SARA-PLA) received 10 mL of sterile saline solution as placebo. To confirm the induction of SARA, the reticular pH was continuously monitored via wireless pH probes. The DMI remained unchanged between SARA and CON cows during the feeding experiment, but was reduced in both treatment groups receiving the LPS infusion compared with SARA-PLA, whereby a significant decline was observed for cows of the SARA-LPS treatment (-38%) compared with CON-LPS (-19%). The LPS infusion did not affect the reticuloruminal pH dynamics, but significantly enhanced ruminal temperature and negatively affected chewing behavior. The ruminal temperature increased after the LPS infusion and peaked about 1 h earlier in SARA-LPS cows compared with the cows of the CON-LPS treatment. Moreover, a significant decline in milk yield was found in SARA-LPS compared with CON-LPS following the LPS infusion. Cows receiving LPS had elevated somatic cell counts, protein, and fat contents in milk as well as decreased lactose contents and pH following the LPS infusion, whereby the changes in milk constituents were more pronounced in SARA-LPS than CON-LPS cows. Rectal temperature and pulse rate were highest 6 h after LPS infusion, but rumen contractions were not affected by the LPS infusion. The data suggest that a single intramammary LPS infusion induced fever and negatively affected feed intake, chewing activity, rectal temperature, and milk yield and composition, whereby these effects were more pronounced in SARA cows.

Fortification of dried distillers grains plus solubles with grape seed meal in the diet modulates methane mitigation and rumen microbiota in Rusitec

The role of dried distillers grains plus solubles (DDGS) and associative effects of different levels of grape seed meal (GSM) fortified in DDGS, used as both protein and energy sources in the diet, on ruminal fermentation and microbiota were investigated using rumen-simulation technique. All diets consisted of hay and concentrate mixture with a ratio of 48:52 [dry matter (DM) basis], but were different in the concentrate composition. The control diet contained soybean meal (13.5% of diet DM) and barley grain (37%), whereas DDGS treatments, unfortified DDGS (19.5% of diet DM), or DDGS fortified with GSM, either at 1, 5, 10, or 20% were used entirely in place of soybean meal and part of barley grain at a 19.5 to 25% inclusion level. All diets had similar DM, organic matter, and crude protein contents, but consisted of increasing neutral detergent fiber and decreasing nonfiber carbohydrates levels with DDGS-GSM inclusion. Compared with the soy-based control diet, the unfortified DDGS treatment elevated ammonia concentration (19.1%) of rumen fluid associated with greater crude protein degradation (~19.5%). Methane formation decreased with increasing GSM fortification levels (≥ 5%) in DDGS by which the methane concentration significantly decreased by 18.9 to 23.4 and 12.8 to 17.6% compared with control and unfortified DDGS, respectively. Compared with control, unfortified DDGS decreased butyrate proportion, and GSM fortification in the diet further decreased this variable. The proportions of genus Prevotella and Clostridium cluster XIVa were enhanced by the presence of DDGS without any associative effect of GSM fortification. The abundance of methanogenic archaea was similar, but their composition differed among treatments; whereas Methanosphaera spp. remained unchanged, proportion of Methanobrevibacter spp. decreased in DDGS-based diets, being the lowest with 20% GSM inclusion. The abundance of Ruminococcus flavefaciens, anaerobic fungi, and protozoa were decreased by the GSM inclusion. As revealed by principal component analysis, these variables were the microorganisms associated with the methane formation. Grape seed meal fortification level in the diet decreased DM and organic matter degradation, but this effect was more related to a depression of nonfiber carbohydrates degradation. It can be concluded that DDGS fortified with GSM can favorably modulate ruminal fermentation.

Effects of black seed oil and Ferula elaeochytris supplementation on ruminal fermentation as tested in vitro with the rumen simulation technique (Rusitec)

Plant bioactive compounds are currently viewed as possible feed additives in terms of methane mitigation and improvement of ruminal fermentation. A range of analyses, including the botanical characterisation, chemical composition and in vitro efficiency, have to be conducted before testing the compounds in vivo. Therefore, the aims of this study were (1) to identify the main bioactive components of black seed (Nigella sativa) oil (BO) and of the root powder of Ferula elaeochytris (FE), and (2) to investigate their effects on ruminal fermentation in vitro, when supplemented in different dosages to a diet (1 : 1, forage : concentrate), using the rumen simulation technique (Rusitec). Main compounds of BO were thymoquinone and p-cymene and α-pinene in FE. Supplementation of the diet with BO and FE did not affect concentration of volatile fatty acids but ammonia concentrations decreased with both supplements (P < 0.001). No effects of supplements on protozoal counts were detected but in vitro disappearance of DM and organic matter tended to increase with 50 mg/L FE (P < 0.1), compared with the control.

Apparent recovery of C18 polyunsaturated fatty acids from feed in cow milk: A meta-analysis of the importance of dietary fatty acids and feeding regimens in diets without fat supplementation

A meta-analysis was conducted using the results of 82 experiments (78 publications, 266 treatments) to investigate the importance of dietary C18 fatty acids (FA) and feeding regimen for milk C18 FA profile and apparent recovery of selected FA relative to intake of these FA or their precursors. Feeding treatments based on lipid-supplemented diets were excluded. Feeding regimens were defined as grazing [including partial and full-time grazing, at dietary concentrate proportions from 0 to 44% dry matter (DM)], forage-based indoor feeding [>65% forage of total DM intake (DMI)], and concentrate-based indoor feeding (forage DMI ≤65% of DMI). Linoleic acid (LLA), α-linolenic acid (ALA), and total C18 FA proportions in milk fat increased linearly with the respective dietary FA content in all feeding regimens tested. This effect was highest in the forage-based indoor feeding. Slopes were lowest for the grazing regimens, especially regarding ALA and the sum of all C18 FA, whereas the intercepts of the prediction equations of milk ALA and total C18 FA proportions were highest for grazing regimens. This indicates that, in grazing cows, factors other than dietary FA contents determine the C18 FA composition of the milk fat. At equal dietary LLA contents, the type of feeding regimen showed no significant effect on LLA proportion in milk fat. Milk fat proportions of rumenic acid and vaccenic acid were positively related to the sum of dietary ALA and LLA contents. Grazing regimens led to the strongest enrichment of rumenic acid and vaccenic acid in milk fat. The apparent recovery of ALA, LLA, and total C18 FA (secreted, % of intake), an estimate for transfer efficiency, decreased with increasing dietary content. This relationship followed a nonlinear decay function. When the dietary content of these FA exceeded a certain threshold (about 0.2, 0.8, and 2.8% of DM for ALA, LLA, and total C18 FA, respectively) the recovery in milk remained constant at about 5, 10, and 82% of the ingested ALA, LLA, and total C18 FA, respectively. At dietary proportions below 0.01% ALA and 1.5% total C18 FA of DM, their apparent recovery in milk fat exceeded 100%. In conclusion, a general inverse relationship between dietary C18 FA and the corresponding apparent recovery in milk fat seems to exist. Within this frame, the effect of different types of feeding regimens on the eventual milk C18 FA profile varies. Among them, grazing pasture appears to provide the most variable properties.

Changes in fibre-adherent and fluid-associated microbial communities and fermentation profiles in the rumen of cattle fed diets differing in hay quality and concentrate amount

ABSTRACT The rumen microbiota enable important metabolic functions to the host cattle. Feeding of starch‐rich concentrate feedstuffs to cattle has been demonstrated to increase the risk of metabolic disorders and to significantly alter the rumen microbiome. Thus, alternative feeding strategies like the use of high‐quality hay, rich in sugars, as an alternative energy source need to be explored. The aim of this study was to investigate changes in rumen microbial abundances in the liquid and solid‐associated fraction of cattle fed two hay qualities differing in sugar content with graded amounts of starchy concentrate feeds using Illumina MiSeq sequencing and quantitative polymerase chain reaction. Operational taxonomic units clustered separately between the liquid and the solid‐associated fraction. Phyla in the liquid fraction were identified as mainly Firmicutes, Proteobacteria and Bacteroidetes, whereas main phyla of the fibre‐associated fraction were Bacteroidetes, Fibrobacteres and Firmicutes. Significant alterations in the rumen bacterial communities at all taxonomic levels as a result of changing the hay quality and concentrate proportions were observed. Several intermicrobial correlations were found. Genera Ruminobacter and Fibrobacter were significantly suppressed by feeding sugar‐rich hay, whereas others such as Selenomonas and Prevotella proliferated. This study extends the knowledge about diet‐induced changes in ruminal microbiome of cattle. &NA; Graphical Abstract Figure. Detailed knowledge was generated about the effects of feeding two contrasting hay qualities, differing in contents of fibrous carbohydrates and sugars with varying levels of concentrate on the rumen bacteria.