Impact of corn silage or corn silage plus protein supplementation on the ingestive and rumination behaviours, ruminal fermentation characteristics and efficiency of grazing dairy cows.

This study's objective was to compare two options of pasture supplementation: corn silage (CS) alone or corn silage mixed with protein concentrate. The experiment was conducted with 18 lactating Holstein cows in mid-lactation in a crossover design that included three treatments and three data collection periods. All cows had access to pasture for 17 h/day with an average herbage allowance of 16 kg dry matter (DM)/cow/day and were offered in-barn corn silage, corn silage mixed with protein concentrate, or no supplementation. Cows were equipped with pH sensors residing in the reticulum and, during the 7-day data collection periods, with a jaw movement recorder. Nonsupplemented cows produced 21.3 kg energy-corrected milk (ECM) and ate 13.3 kg DM herbage at pasture. Cows supplemented with corn silage and corn silage plus protein produced 2.5 and 4.5 kg/day more ECM, respectively, consumed 3.4 and 3.3 kg/day more DM in total, respectively, ate for a shorter period of time, and ruminated longer than their nonsupplemented peers. Supplemented cows were almost able to cover their energy requirements and mobilised less body mass in contrast to the nonsupplemented cows. Cows offered corn silage plus protein showed increased ECM production, increased milk urea content and lower nitrogen use efficiency (NUE) compared to cows supplemented with corn silage only. Nonsupplemented dairy cows had the highest milk urea content and performed worst in terms of NUE. The best feed conversion efficiency resulted from the nonsupplemented dairy cows and those supplemented with corn silage plus protein. In nonsupplemented cows, the high feed conversion efficiency seemed to be due to the increased mobilisation of body mass. As a result of the starch-rich supplementations, the ruminal acetic:propionic acid ratio became smaller, and the proportions of n-butyric acid increased. The mean reticular pH values did not substantially vary across the three feeding treatments. For the choice of a supplementation option, herbage allowance and cost of supplement will have to be considered, but aspects of feed-food competition as well as animal welfare should not be ignored.

Digestibility of dinosaur food plants revisited and expanded: Previous data, new taxa, microbe donors, foliage maturity, and seasonality.

Although the living relatives of the Mesozoic flora were once assumed to constitute a nutritionally poor diet for dinosaur herbivores, in vitro fermentation of their foliage has shown that gymnosperms, ferns, and fern relatives can be as highly digestible as angiosperm grasses and dicots. Because nutritional information cannot be preserved in the fossil record, this laboratory approach, first published in 2008, provides a novel alternative to evaluate the digestive quality of the plants that were available to dinosaur megaherbivores such as sauropods. However, very few further studies have since been conducted to supplement and confirm the high fermentative capacity of nonangiospermous taxa. Here we show that the living relatives of the Araucariaceae and Equistaceae are consistently highly digestible, even between taxa and when influenced by environmental and biological factors, while fern taxa are inconsistent on the family level. These results reinforce previous findings about the high energetic potential of Jurassic-age plant families. Fourteen species of fern and gymnosperm foliage from five Jurassic families were collected in the spring and fall, then analyzed for their digestibility using the in vitro Hohenheim gas test. Equisetum, Araucaria, and Angiopteris were the most digestible genera in both seasons, while Agathis, Wollemia, and Marattia were the least digestible. The season in which specimens were collected was found to have to a significant effect on gas production in four out of 16 samples (P < 0.05). Furthermore, leaf maturity influences digestibility in Marattia attenuata (P < 0.05), yet not in Cyathea cooperi (P = 0.24). Finally, the species of the rumen fluid donor did not influence digestibility (P = 0.74). With the original data set supplemented by one new genus and four species, this study confirms and expands previous results about the nutritional capacity of the living relatives of the Jurassic flora.

Productive, physiological and nutritional responses of laying hens fed different dietary levels of turmeric powder.

This study aimed to determine the impact of supplementation of turmeric powder on laying performance, egg quality, nutrient digestibility and some blood metabolites in laying hens. A total of one hundred and twenty Bovans Brown laying hens (55 weeks old) were assigned to one of four treatment diets (n = 30) for 12 weeks including turmeric powder at 0, 2.5, 5 or 7.5 g/kg respectively. The results revealed that egg production, egg weight and egg mass were significantly increased (p < 0.05), and the feed conversion ratio was significantly improved (p < 0.012) with increasing levels of turmeric in the laying hen diet. Egg thickness and Haugh unit were linearly increased (p < 0.01) with increasing supplementation levels. Moreover, compared with the control diet, the levels of turmeric powder supplementation significantly improved nutrient digestibility (p < 0.001). Moreover, the serum metabolic profile revealed that serum total cholesterol, aspartate aminotransferase, creatinine and urea concentrations were linearly decreased with increasing turmeric powder supplementation to hen diets. In conclusion, the inclusion of turmeric powder at 2.5, 5 or 7.5 g/kg diet improved egg production, nutrient digestibility, egg quality and serum metabolic profile and may be used as a feed additive in laying hens' nutrition. However, results indicate that the best improvement was observed when 5 g/kg were supplemented.

Influence of pre-grazing herbage mass on bite mass, eating behaviour, and dairy cow performance on pasture.

Knowledge about individual daily herbage dry matter (DM) intake (DMI) helps identifying efficient dairy cows and adapting supplementation better to herbage intake and nutrient requirements of grazing dairy cows. With the aid of behavioural characteristics, raw data recorded with the RumiWatch (RW) system and processed with the RW converter 0.7.3.31 (C31), estimation of herbage DMI may be possible. First, C31, which allows differentiation of prehension bites and mastication chews, was validated through direct observation of behavioural characteristics and compared to the previous RW converter 0.7.3.11 (C11). Further, the influence of a low and high pre-grazing herbage mass (HM), with the same target herbage allowance (HA), on bite mass, DMI, number of prehension bites, and milk production was investigated. In total, 24 lactating Holstein cows were pairwise allotted to one of two HM treatments. The cows received a new pasture paddock twice per day with a daily target HA of 22 kg DM per cow/day. On average, low HM (LHM) and high HM (HHM) paddocks had an HM of 589 and 2288 kg DM/ha, respectively, above 6.7 click units (1 CU = 0.5 cm). Overall, LHM cows produced 2.7 kg/day more milk and 2.5 kg/day more energy-corrected milk, had the same herbage DMI and a similar prehension bite mass. The averaged bite mass per week was 0.49 g DM/bite (LHM) or 0.47 g DM/bite (HHM), respectively. A longer eating time (617 vs. 559 min/day) and a shorter rumination time (297 vs. 365 min/day) were observed for the LHM cows compared with the HHM cows. The validation of the RW showed similar results for C11 and C31 apart from prehension bites, where C31 showed a mean absolute deviation of 12.4%. Pre-grazing HM had no effect on relevant behavioural characteristics for prospective intake estimation, namely, bite mass and number of prehension bites.

Sensitivity of ponies to sodium in the drinking water.

Horses lose high amounts of Na through excessive sweating. These fluid losses can often not be replaced completely by voluntary water intake, requiring saline solutions as rehydration therapy to regain electrolyte balance. The experiment aimed to evaluate the sensitivity and tolerance of Shetland ponies towards different Na concentrations in their drinking water and contained three phases: (1) control: only fresh water provided; (2) pairwise-preference test: choice between fresh water and saline solution with stepwise increasing sodium chloride (NaCl) concentration (0.25%, 0.5%, 0.75%, 1.0%, 1.25%, or 1.5%); and (3) free-choice test: six simultaneously provided buckets containing NaCl concentrations of 0%, 0.25%, 0.5%, 0.75%, 1.0%, or 1.25%. During the pairwise test, the ponies did not distinguish between fresh and 0.25% NaCl-water but demonstrated clear preference for 0.5%, whereas >0.75% NaCl was avoided/rejected. During the free-choice test, a pronounced preference of fresh over saline water was exhibited. The Na intake via salt lick was not reduced as response to higher Na intakes via water. The ponies exhibited a remarkable sensory discrimination capacity to detect different NaCl concentrations in their drinking water. The acceptance of solutions with low NaCl levels (0.25/0.5%) without adverse effects demonstrates potential as rehydration solution for voluntary intake.

Weaning age influences indicators of rumen function and development in female Holstein calves.

BACKGROUND: Prenatal and postnatal conditions are crucial for the development of calves. Primiparous cows are still maturing during pregnancy, thus competing with the nutritional needs of their offspring. Therefore, mature cows might provide a superior intrauterine condition. Furthermore, weaning calves at an older age might affect them positively as well by reducing stress and offering time for various organs and their functions to develop. We aimed to evaluate effects of mothers' parity and calves' weaning age on gastrointestinal development and corresponding acid-base balance. Fifty-nine female German Holstein calves (about 8 days old) were investigated in a 2 × 2 factorial experiment with factors weaning age (7 vs. 17 weeks) and parity of mother (primiparous vs. multiparous). Calves were randomly assigned to one of these four groups. Animal behavior that was observed included resting, chewing and active behavior. RESULTS: Behavioral patterns were interactively affected by time and weaning age. Rumen sounds per 2 min increased in early-weaned calves during their weaning period. In late-weaned calves a consistently increase in rumen sounds was already recorded before their weaning period. Urinary N-containing compounds (creatinine, hippuric acid, uric acid, urea, allantoin) were interactively affected by time and weaning age. Concentrations of all measured compounds except urea increased during early weaning. All except hippuric acid concentration decreased in early-weaned calves after weaning. In late-weaned calves allantoin and uric acid increased before weaning and did not change during weaning. CONCLUSION: These results suggest that late-weaned calves developed adequate rumen functions and acid-base balance, whereas early-weaned calves might have suffered from ruminal acidosis and catabolism. Weaning calves at 7 weeks of age might be too early for an adequate rumen development.

Amino acid pattern of rumen microorganisms in cattle fed mixed diets-An update.

Rumen microorganisms turn small N-containing compounds into amino acids (AA) and contribute considerably to the supply of AA absorbed from the small intestine. Previous studies summarized the literature on microbial AA patterns, most recently in 2017 (Sok et al. Journal of Dairy Science, 100, 5241-5249). The present study intended to identify the microbial AA pattern typical when feeding Central European diets and a maximum proportion of concentrate (PCO; dry matter (DM) basis) of 0.60. Data sets were created from the literature for liquid (LAB)- and particle (PAB)-associated bacteria, total bacteria and protozoa, including 16, 9, 27 and 8 studies and 36, 21, 60 and 18 diets respectively. Because the only differences detected between LAB and PAB were slightly higher Phe and lower Thr percentages in PAB (p < 0.05), results for bacteria were pooled. A further data set evaluated AA-N (AAN) as a proportion of total N in microbial fractions and a final data set estimated protozoal contributions to total microbial N (TMN) flow to the duodenum, which were used to calculate weighted TMN AA patterns. Protozoa showed higher Lys, Asp, Glu, Ile and Phe and lower Ala, Arg, Gly, Met, Ser, Thr and Val proportions than bacteria (p < 0.05). The AAN percentage of total N in bacteria and protozoa showed large, unexplained variations, averaging 79.0% and 70.6% (p > 0.05) respectively. Estimation of protozoal contribution to TMN resulted in a cattle-specific mixed model including PCO and DM intake (DMI) per unit of metabolic body size (kg0.75 ) as fixed effects (RMSE = 3.77). With moderate PCO and DMI between 80 and 180 g/kg0.75 , which corresponds to a DMI of approximately 10 to 25 kg in a cow with 650 kg body weight, protozoal contribution ranged between 9% and 26% of TMN. Within this range, the estimated protozoal contribution to TMN resulted in minor effects on the total microbial AA pattern.

Increasing food intake affects digesta retention, digestibility and gut fill but not chewing efficiency in domestic rabbits (Oryctolagus cuniculus).

In ruminants, the level of food intake affects net chewing efficiency and hence faecal particle size. For nonruminants, corresponding data are lacking. Here, we report the effect of an increased food intake of a mixed diet in four domestic rabbit does due to lactation, and assess changes in particle size (as determined by wet sieving analysis) along the rabbit digestive tract. During lactation, rabbits achieved a distinctively higher dry matter intake than at maintenance, with a concomitant reduction in mean retention times of solute and particle markers, an increase in dry matter gut fill, a reduction in apparent digestibility of dry matter, and an overall increase in digestible dry matter intake. By contrast, there was no change in faecal mean particle size (mean ± SD: 0.58 ± 0.02 vs. 0.56 ± 0.01 mm). A comparison of diet, stomach content and faecal mean particle size suggested that 98% of particle size reduction occurred due to ingestive mastication and 2% due to digestive processes. Very fine particles passing the finest sieve, putatively not only of dietary but mainly of microbial origin, were particularly concentrated in caecum contents, which corresponds to retention of microbes via a 'wash-back' colonic separation mechanism, to concentrate them in caecotrophs that are re-ingested. This study gives rise to the hypothesis that chewing efficiency on a consistent diet is not impaired by intake level in nonruminant mammals.

Estimation of diet organic matter digestibility in grazing dairy cows.

Precise and continual information on the energy supply from pasture is mandatory for managing grazing ruminants. Therefore, estimating the organic matter (OM) digestibility from faecal crude protein concentration using the regression equation, OM digestibility [%] = 79.76-107.7 · e(-0.01515 · faecal crude protein [g/kg OM]), is known to be a suitable tool. However, essential information regarding faeces sampling times and the required number of samples are not yet available. We therefore analysed the OM digestibility data of an experiment with dairy cows grazing two pasture types and receiving two concentrate types over 6 d in three independent runs. Both pasture type and grazing day affected the OM digestibility estimates, whereas concentrate type and intake did not, indicating that this method reliably detects small changes in OM digestibility of pasture without being interfered by moderate concentrate supplementation, selective grazing behaviour or differences in feed intake. Likewise, as sampling time did not influence OM digestibility, faeces sampling once daily can be recommended to be sufficient for an accurate estimation of OM digestibility. The variance within pasture type and grazing day amounted for 1.1 percentage units of estimated OM digestibility, which enabled to define the minimum sample number required to detect given differences in OM digestibility with adequate statistical certainty. In conclusion, estimating OM digestibility from faecal crude protein concentration is an applicable and sensitive method to reliably detect differences in the quality of ingested pasture using a limited number of animals. Therefore, instructions for faeces sample collection  were provided.

Increasing feed intake in domestic goats (Capra hircus): Measured effects on chewing intensity are probably driven by escape of few, large particles from the forestomach.

On the one hand, oral processing - mastication - is considered a relatively inflexible component of mammalian feed acquisition that constrains instantaneous intake rates. On the other hand, experimental data shows that the level of feed intake affects faecal particle size and hence net chewing efficiency in ruminants, with larger particles occurring in the faeces at higher intakes. Here, we report the effect of an increased feed intake during maintenance (L1), late (200% of L1) and peak lactation (300% of L1) of a consistent diet (hay:concentrates 50:50) in eight domestic goats on various measures of digestive physiology including faecal mean particle size (MPS). Increasing intake led to an increased gut fill, a reduction in digesta retention times, and an increase in faecal MPS (from 0.57 to 0.72 mm). However, this was an effect of the large particle fraction (>2 mm) being disproportionately excreted at higher intakes; if MPS was assessed on the basis of particles below the typical escape threshold (≤1 mm), there was no difference between intake levels. These findings suggest that the effect of intake on the calculated net chewing efficiency in ruminants may rather be an effect of increased large particle escape from the forestomach than a reduced chewing intensity per bolus during ingestion or rumination.

Predicting the transfer of contaminants in ruminants by models - potentials and challenges.

Undesirable substances in feed can transfer into foods of animal origin after ingestion by livestock animals. These contaminants in food may threaten consumer health. Commonly, feeding trials are conducted with animals to assess the transfer of undesirable substances into animal tissues or milk. Such feeding trials explore the effects of the various physiological systems (e.g., ruminant and non-ruminant gastro-intestinal tracts) as well as different livestock production intensities on transfer. Using alternative methods to mimic the complex physiological processes of several organs is highly challenging. This review proposes a potential cascade of in vitro and ex vivo models to investigate the transfer of contam­inants from feed into foods of animal origin. One distinct challenge regarding the models for ruminants is the simulation of the forestomach system, with the rumen as the anaerobic fermentation chamber and its epithelial surfaces for absorption. Therefore, emphasis is placed on in vitro systems simulating the rumen with its microbial ecosystem as well as on ex vivo systems to replicate epithelial absorption. Further, the transfer from blood into milk must be evaluated by employing a suitable model. Finally, in silico approaches are introduced that can fill knowledge gaps or substitute in vitro and ex vivo models. Physiologically-based toxicokinetics combines the information gained from all alternative methods to simulate the transfer of ingested undesirable substances into foods of animal origin.

Phosphorus digestibility and metabolisable energy concentrations of contemporary wheat, barley, rye and triticale genotypes fed to growing pigs.

This study was conducted to determine apparent total tract digestibility (ATTD) of phosphorus (P) and metabolisable energy (ME) concentrations for pigs of 32 different genotypes (n = 8 per grain species) of barley, rye, triticale and wheat. All genotypes were grown at the same location under the same field conditions and were fed to growing castrated crossbred pigs (initial body weight: 31.1 ± 6.95 kg) using a series of duplicate 3 × 3 Latin square designs. A basal ration, which was deficient in P, and 32 experimental rations containing 400 g/kg DM of the basal ration and 600 g/kg DM of the corresponding cereal grain were mixed. Pigs were kept in metabolism crates and the total collection method was used for separate faeces and urine collections with 7-d adaptation and 7-d collection periods. The mean ATTD of P was greater (p < 0.05) for wheat than for triticale, rye or barley (59.4%, 50.4%, 44.9% and 44.4%, respectively, for the mean of each grain species). Within-grain species differences (p < 0.05) among genotypes were obtained for ATTD of P of barley and triticale. The concentrations of ME of triticale and wheat were higher (p < 0.05) than that of barley and rye (16.1 and 16.2 vs. 14.9 and 14.8 MJ ME/kg DM, respectively). Differences in ME concentration among genotypes within a grain species (p < 0.05) were found for barley, triticale and wheat. No differences were found for rye. Compared to literature data the present study showed, in part, considerable differences in ATTD of P and ME concentration. These results should be taken into account for accurate pig ration formulation with regard to minimised P output and efficient use of ME. No significant relationships were detected between ATTD of P and phytic acid concentration or phytase activity in the grain genotypes in this study.

Differently Pre-treated Alfalfa Silages Affect the in vitro Ruminal Microbiota Composition.

Alfalfa (Medicago sativa L.) silage (AS) is an important feedstuff in ruminant nutrition. However, its high non-protein nitrogen content often leads to poor ruminal nitrogen retention. Various pre-ensiling treatments differing with respect to dry matter concentrations, wilting intensities and sucrose addition have been previously shown to improve the quality and true protein preservation of AS, and have substantial effects on in vitro ruminal fermentation of the resulting silages. However, it is unknown how these pre-ensiling treatments affect the ruminal microbiota composition, and whether alterations in the microbiota explain previously observed differences in ruminal fermentation. Therefore, during AS incubation in a rumen simulation system, liquid and solid phases were sampled 2 and 7 days after first incubating AS, representing an early (ET) and late (LT) time point, respectively. Subsequently, DNA was extracted and qPCR (bacteria, archaea, and anaerobic fungi) and prokaryotic 16S rRNA gene amplicon sequence analyses were performed. At the ET, high dry matter concentration and sucrose addition increased concentrations of archaea in the liquid phase (P = 0.001) and anaerobic fungi in the solid phase (P < 0.001). At the LT, only sucrose addition increased archaeal concentration in the liquid phase (P = 0.014) and anaerobic fungal concentration in the solid phase (P < 0.001). Bacterial concentrations were not affected by pre-ensiling treatments. The prokaryotic phylogenetic diversity index decreased in the liquid phase from ET to LT (P = 0.034), whereas the solid phase was not affected (P = 0.060). This is suggestive of a general adaption of the microbiota to the soluble metabolites released from the incubated AS, particularly regarding the sucrose-treated AS. Redundancy analysis of the sequence data at the genus level indicated that sucrose addition (P = 0.001), time point (P = 0.001), and their interaction (P = 0.001) affected microbial community composition in both phases. In summary, of the pre-ensiling treatments tested sucrose addition had the largest effect on the microbiota, and together with sampling time point affected microbiota composition in both phases of the rumen simulation system. Thus, microbiota composition analysis helped to understand the ruminal fermentation patterns, but could not fully explain them.

Peppermint and its respective active component in diets of broiler chickens: growth performance, viability, economics, meat physicochemical properties, and carcass characteristics.

This study was conducted to investigate effects of dietary peppermint leaves and menthol supplementations on performance, survivability rate, cost economics, meat physicochemical properties, and carcass characteristics of broiler chicks. A total of 384 1-day-old, unsexed Ross 308 broiler chicks, were divided into 2 experiments. Each experiment included 192 birds that were assigned to 4 dietary treatments that included peppermint leaves at concentrations of 0, 5, 10, or 15 g/kg in the first experiment or menthol at concentrations of 0, 26, 52, or 78 mg/kg in the second experiment. Each treatment had 6 replicate pens with 8 birds. The experiments lasted for 35 D. The peppermint leaves contained 1.48% essential oil that contained 35.1% menthol, and the levels of menthol were selected based on the concentrations in peppermint leaf levels. Body weight and body-weight gain increased with the increase in dietary peppermint leaves (linear, P < 0.01) and menthol concentrations (linear, quadratic, P < 0.01) during the trial periods. In addition, the feed intake linearly increased (P < 0.01) with increasing peppermint leaves or menthol levels and, in turn, caused linear improvements (P < 0.01) in feed conversion values. Interestingly, a lower mortality rate was recorded in the supplementation groups and, therefore, a higher net return was observed. However, pH values and drip loss percentage of breast and leg muscles were not affected by either dietary peppermint levels or menthol levels. Increasing peppermint or menthol levels decreased (P < 0.001) cook-loss percentage of breast and leg muscles. On the other hand, dietary supplementation of peppermint leaves or menthol had no effect (P ≥ 0.05) on the relative weights of dressing, breast, leg, liver, heart, gizzard, spleen, or pancreas. Interestingly, abdominal fat percentage was decreased by either supplemental peppermint or menthol. Hence, the present investigation demonstrates that peppermint leaves can be used as an effective novel nutritional bio-agent up to 15 g/kg to improve the performance of broiler chicks, mainly due to its active component.

Effects of ethyl ester supplementation to forage on short-term dry matter intake and preference by goats.

In whole-crop maize silages with atypical smell and decreased acceptance by ruminants, high concentrations of the volatile organic compounds ethyl acetate (EA) and ethyl lactate (EL) were detected. The aim of this study was to evaluate the impact of different concentrations of ethyl esters added to forage on preference and short-term feed intake of goats. In the first of three trials, whole-crop maize silage was supplemented with different concentrations of EA and EL and then vacuum-stored before use. Forages sampled during the preference trial showed a good recovery of EL with a high accordance of target (naturally formed + supplemented) and analysed concentrations. Supplemented EA was not recovered, making transient storage of substrates before use in feeding trials equivocal. However, four treatments with different concentrations of EL (approximately 330, 560, 920 and 1300 mg/kg dry matter (DM)) were used for the preference trial. In Trials 2 and 3, EA and EL (with and without ethanol, respectively) were added to grass hay directly before offering the feed, each in concentrations of 0, 600 and 1200 mg/kg DM to have six treatments each. In all trials, each possible combination of treatments was offered to Saanen-type wethers (n = 10, Trial 1; n = 5, Trials 2 and 3) as free choice in preference trials. In Trial 1, there was only a weak impact of EL on preference behaviour as goats avoided medium EL concentrations, but did not avoid silages with higher concentrations. In Trials 2 and 3, there was no influence of added volatiles on short-term DM intake and preference at all. It can be concluded that it is unlikely that ethyl esters as single substance or in combination with ethanol affect preference behaviour and feed intake of ruminants. Possibly a combination or still unidentified fermentation products cause avoidance instead of a single compound.

Contribution of different rumen microbial groups to gas, short-chain fatty acid and ammonium production from different diets-an approach in an in vitro fermentation system.

In this study, the relative contribution of different microbial groups to ruminal metabolism was investigated for different diets. The rumen microbial cultures included whole rumen fluid, fungi + protozoa, bacteria + protozoa, protozoa and bacteria + fungi and were established by physical and chemical methods. Gas production, short-chain fatty acid (SCFA) and ammonium production were measured at 24 hr in in vitro incubations using the Hohenheim gas test (HGT) procedure. Seven donor animal diets with different concentrate-to-roughage ratios (C:R: 10:90, 30:70, 50:50, 70:30, 70:30BC (BC = NaHCO3 ), 90:10 and 90:10BC) and five HGT diets (C:R: 10:90, 30:70, 50:50, 70:30 and 90:10) were formulated. Incubations in the HGT were always based on inoculum from sheep diets with the respective C:R ratio. Gas and ammonium production increased (p < 0.001) as a result of a gradual increase in concentrate proportion of the diets. In general, SCFA production followed the same trend. Whole rumen fluid and bacteria + fungi produced approximately 50% higher gas volume than protozoa and fungi + protozoa fractions, whereas gas production with bacteria + protozoa was at an intermediate level. Coculture of protozoa either with bacteria or with fungi produced more ammonium. Populations without bacteria were characterized by a particularly high acetate/propionate ratio. Although an interaction between microbial group and diet was observed for several variables, no clear direction could be established. Manipulating rumen fluid by selectively suppressing specific rumen microbial groups may be a helpful tool in elucidating their role in nutrient degradation and turnover in vitro.

Thyme oil inclusion levels in a rabbit ration: Evaluation of productive performance, carcass criteria and meat quality under hot environmental conditions.

The aim of this study was to determine the impact of thyme essential oil supplementation in rabbit rations on performance, carcass criteria, and meat quality under hot environmental conditions. A total of 75, 4-week-old Californian male rabbits were assigned to 5 dietary treatments until 12 weeks of age. The rabbits were reared in an open house system (38 °C average ambient temperature and 26% to 35% relative humidity). Treatments were as follows: unsupplemented standard ration, negative control (CON); standard ration supplemented with 1.50 g/kg olive oil as carrier, positive control (POS); POS + 50 mg/kg thyme oil (TO1); POS + 100 mg/kg thyme oil (TO2); and POS + 150 mg/kg thyme oil (TO3). Dietary thyme oil up to 150 mg/kg improved (P < 0.001) feed intake and growth performance in comparison to CON. The highest average daily gain and most efficient feed conversion ratio (linear, P < 0.001 and quadratic, P < 0.001) were found for TO1 followed by TO2, TO3 and POS, respectively. The incorporation of thyme oil improved (P < 0.001) carcass criteria and decreased (P < 0.001) perirenal and scapular fat without any side effects on internal organs. Notably, the water holding capacity of rabbit meat was greater (P < 0.001), and the lipid oxidation was lower (P < 0.01) in rabbits fed treated rations compared with CON. Differences were also recorded in oxymyoglobin and metmyoglobin contents in rabbit meat among treatments. In conclusion, thyme oil of a specified composition and to be added to a rabbit ration up to 100 mg/kg using 1.50 g/kg olive oil as a carrier can be used as an efficient feed additive for improving productive performance of rabbits under hot environmental conditions.

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation.

Nitrogenous emissions from ruminant livestock production are of increasing public concern and, together with methane, contribute to environmental pollution. The main cause of nitrogen-(N)-containing emissions is the inadequate provision of N to ruminants, leading to an excess of ammonia in the rumen, which is subsequently excreted. Depending on the size and molecular structure, various bacterial, protozoal and fungal species are involved in the ruminal breakdown of nitrogenous compounds (NC). Decelerating ruminal NC degradation by controlling the abundance and activity of proteolytic and deaminating microorganisms, but without reducing cellulolytic processes, is a promising strategy to decrease N emissions along with increasing N utilization by ruminants. Different dietary options, including among others the treatment of feedstuffs with heat or the application of diverse feed additives, as well as vaccination against rumen microorganisms or their enzymes have been evaluated. Thereby, reduced productions of microbial metabolites, e.g. ammonia, and increased microbial N flows give evidence for an improved N retention. However, linkage between these findings and alterations in the rumen microbiota composition, particularly NC-degrading microbes, remains sparse and contradictory findings confound the exact evaluation of these manipulating strategies, thus emphasizing the need for comprehensive research. The demand for increased sustainability in ruminant livestock production requests to apply attention to microbial N utilization efficiency and this will require a better understanding of underlying metabolic processes as well as composition and interactions of ruminal NC-degrading microorganisms.

Quantification of Methane and Ammonia Emissions in a Naturally Ventilated Barn by Using Defined Criteria to Calculate Emission Rates.

Extensive experimentation on individual animals in respiration chambers has already been carried out to evaluate the potential of dietary changes and opportunities to mitigate CH4 emissions from ruminants. Although it is difficult to determine the air exchange rate of open barn spaces, measurements at the herd level should provide similarly reliable and robust results. The primary objective of this study was (1) to define a validity range (data classification criteria (DCC)) for the variables of wind velocity and wind direction during long-term measurements at barn level; and (2) to apply this validity range to a feeding trial in a naturally cross-flow ventilated dairy barn. The application of the DCC permitted quantification of CH4 and NH3 emissions during a feeding trial consisting of four periods. Differences between the control group (no supplement) and the experimental group fed a ration supplemented with condensed Acacia mearnsii tannins (CT) became apparent. Notably, CT concentrations of 1% and 3% of ration dry matter did not reduce CH4 emissions. In contrast, NH3 emissions decreased 34.5% when 3% CT was supplemented. The data confirm that quantification of trace gases in a naturally ventilated barn at the herd level is possible.

Ensiled sugar beets as dietary component and their effect on preference and dry matter intake by goats.

This study examines the influence of ensiled sugar beets (Beta vulgaris ssp. vulgaris) on preference and short-time dry matter (DM) intake of goats. Whole sugar beets were ensiled either without any silage additive (sugar beet silage (SBS)) or with a chemical additive (6 l/t) containing 85% formic and propionic acids (treated sugar beet silage (TBS)) and were chopped after ensiling. The influence of different proportions of SBS (0%, 6.25%, 12.5%, 18.75% and 25% of dietary DM) and TBS (0%, 5%, 10%, 15% and 20% of DM) in partial mixed rations on short-time DM intake by goats (adult Saanen type wethers; n = 10) was studied in two separate, independent trials. Preference behaviour was investigated by offering the goats two different experimental diets per day and offer each possible combination of them (n = 10) once throughout the trial. On this basis, the mean DM intake (within 30 min and 3 h) of each experimental diet was determined. Both sugar beet silages showed good fermentation quality with low pH. By using the chemical silage additive, the production of ethanol was reduced and considerable amounts of sugar were preserved. In the short-term preference experiment, increasing concentrations of sugar beet silage in the ration increased DM intake (p < 0.05) in a linear way with a strong preference for those diets containing high amounts of sugar beet silage. Initial DM intake after 30 min was 4-5 fold increased for diets containing the highest beet concentration. It is assumed that the preference was positively influenced by sugar and sweet taste or the associated higher concentration of metabolisable energy.