Effects of a salivary stimulant, slaframine, on ruminal fermentation, bacterial protein synthesis and digestion in frequently fed steers

Effect of induced saliva flow on fluid retention time, ruminal microbial yield and methane emission in cattle

Both in vitro and animal studies indicated that a higher dilution rate is related to a more efficient microbial synthesis and a lower methane (CH₄ ) yield. The latter could be a consequence of the former, as an increase in microbial cell synthesis offers an alternative hydrogen sink competing with methanogenesis. To test this assumption in live animals, we applied a saliva stimulant, pilocarpine, to modify liquid flow rate in cattle. Four non-lactating cows (750 ± 71 kg) were fed forage only (restricted to constant intake) in a 4 × 4 Latin square design with oral doses of 0, 1, 2.5 and 5mg pilocarpine/kg body weight and day. We quantified feed and water intake, ruminal and total tract mean retention time (MRT) of solute and particle markers, ruminal microbial yield (via urinary purine bases or metabolic faecal nitrogen), CH₄ emission, digestibility, chewing behaviour, reticular motility and rumen fluid parameters. The effect of induced saliva flow was evident by visibly increased salivation and water intake. Increasing the pilocarpine dosages resulted in a linearly decreased MRT of fluid and small particles (p < 0.001 and p< 0.05, respectively) and methane yield as related to digested DM (p < 0.05), the latter at a magnitude of 5%. No effect of treatment was found on ruminal microbial yield estimated via purine derivates. Metabolic faecal N as an indicator of microbial growth linearly correlated with pilocarpine dosages (p < 0.05). No significant relationship was found between pilocarpine dosages and large particle MRT, nutrient digestibility, ruminal pH and short-chain fatty acids. In conclusion, different from some in vitro studies, there was little indication of a reciprocal effect of CH₄ and microbial biomass production in cows fed a forage-only diet.

Folate promotes S-adenosyl methionine reactions and the microbial methylation cycle and boosts ruminants production and reproduction

Folate has gained significant attention due to its vital role in biological methylation and epigenetic machinery. Folate, or vitamin (B₉), is only produced through a de novo mechanism by plants and micro-organisms in the rumen of mature animals. Although limited research has been conducted on folate in ruminants, it has been noted that ruminal synthesis could not maintain folate levels in high yielding dairy animals. Folate has an essential role in one-carbon metabolism and is a strong antiproliferative agent. Folate increases DNA stability, being crucial for DNA synthesis and repair, the methylation cycle, and preventing oxidation of DNA by free radicals. Folate is also critical for cell division, metabolism of proteins, synthesis of purine and pyrimidine, and increasing the de novo delivery of methyl groups and S-adenosylmethionine. However, in ruminants, metabolism of B₁₂ and B₉ vitamins are closely connected and utilization of folate by cells is significantly affected by B₁₂ vitamin concentration. Supplementation of folate through diet, particularly in early lactation, enhanced metabolic efficiency, lactational performance, and nutritional quality of milk. Impaired absorption, oxidative degradation, or deficient supply of folate in ruminants affects DNA stability, cell division, homocysteine remethylation to methionine, de novo synthesis of S-adenosylmethionine, and increases DNA hypomethylation, uracil misincorporation into DNA, chromosomal damage, abnormal cell growth, oxidative species, premature birth, low calf weight, placental tube defects, and decreases production and reproduction of ruminant animals. However, more studies are needed to overcome these problems and reduce enormous dietary supplement waste and impaired absorption of folate in ruminants. This review was aimed to highlight the vital role of folic acid in ruminants performance.

Effects of rumen-protected pantothenate supplementation on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows

BACKGROUND

Lactation performance of dairy cow has considerably increased with animal breeding and management improvement in recent years. Ruminal net synthesised pantothenic acid is insufficient to meet the requirement of high producing dairy cows. The objective was to investigate the effects of rumen-protected pantothenate (RPP) on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows.

RESULTS

Dry matter (DM) intake tended to increase, whereas milk yields, milk fat percentage and yield, body condition score (BCS) changes and net energy output except for maintenance increased linearly with increasing RPP supplementation. Ruminal pH and ammonia N concentration tended to decrease, total VFA tended to increase, while acetate-to-propionate ratio increased linearly with increasing RPP supplementation. Digestibilities of DM, organic matter and crude protein increased linearly, but neutral detergent fibre and acid detergent fibre digestibility tended to increase. Blood glucose, total protein, non-esterified fatty acids, pantothenic acid, pantothenate kinase, succinyl CoA, acyl carrier protein and acetyl CoA also increased linearly with increasing RPP supplementation.

CONCLUSION

The results indicated that supplementary RPP improved lactation performance, nutrient digestion and blood parameters in a dose-dependent manner, and the optimal dose was 12 g RPP per cow per day in the current study. © 2017 Society of Chemical Industry.

Transmission of weed seed by livestock: a review

Weed seeds are readily translocated by livestock by attachment to their coat, by consumption or in vehicles used for transporting them. Livestock transport by land, sea and air is increasing worldwide, which together with increasing livestock production, is anticipated to escalate the risk of weed incursions and displace native flora. There is a particular risk of widespread weed seed dissemination in Australia with its extensive grazing practices and significant amounts of livestock movement. Consumption of weed seeds is largely dependent on grazing management practices, with lax grazing facilitating inflorescence production, the seeds of which may then be consumed if grazing pressure increases. Seed passage through the animal depends on the type of seed and animal intake and is typically 30–70 h. The germination rate of weed seeds is usually reduced by passage through the animal, but faeces in which seed is excreted also have the potential to provide nutrients and moisture to support the germinated plant. Seed viability is largely determined by the type of seed dormancy (particularly the permeability of the seed coat) and the species of livestock. It is concluded that weed seed transmission by livestock is a growing concern that requires addressing at local, national and international levels.

Effect of abomasal infusion of saliva on reticular motility and ruminal liquid contents of steers

Two Holstein and two Jersey steers with ruminal and abomasal cannulas were used in a 4 x 4 Latin square experiment to test the effects of abomasal infusion of saliva on reticular contractions and on contents of the reticulorumen. Steers were fed a ration based on sorghum silage (58.3% DM) at 2-h intervals in 12 equal amounts at 1.25 times the maintenance requirement. Saliva was collected from eight esophageally fistulated steers, pooled, and stored frozen at -20 degrees C. Saliva was mixed with McDougall's buffer (0, 33.3, 66.7, or 100% saliva) and infused abomasally at a rate of 1.5 L/h for 3 h. Abomasal infusion of saliva resulted in linear decreases in ruminal liquid and DM contents. Ruminal dilution rate tended to be faster for infused steers as concentration of saliva increased. Frequency of reticular contractions increased linearly as saliva infusion increased. The influence of saliva infusion on duration of reticular contractions was complicated by inverse patterns of response for each separate phase of the reticular contraction. The first phase of the contraction was influenced by saliva infusion in a negative, quadratic manner; the second phase exhibited an opposite response pattern. A quadratic effect was evident for both amplitude and area of contractions, indicating that the contraction strength was decreased at the intermediate salivary infusion. Postruminal passage of saliva may influence ruminal digestive function by regulating reticular motility and digesta passage.

Neurotoxic mycotoxins: a review of fungal toxins that cause neurological disease in large animals

Five mycotoxins found in concentrates or roughages have been shown to cause neurologic disease in livestock. Fumonisin B1 is produced by Fusarium moniliforme and causes leukoencephalomalacia in horses. Swainsonine and slaframine are produced by Rhizoctonia leguminicola and cause mannose accumulation and parasympathomimetic effects, respectively. Lolitrems from Acremonium lolii and paspalitrems from Claviceps paspali are tremorgens found in grasses.

Involvement of opioid peptides from casein on reticular motility and digesta passage in steers

Experiment 1 determined the effects of incremental abomasal casein infusion on reticular motility and digesta passage of mature steers in a 4 x 4 Latin square study. Casein solutions were infused at 0, 1.25, 2.5, and 5.0% (wt/vol) for 3 h at 16.7 ml/min. Steers were fed for maintenance every 2 h. Casein resulted in a linear decrease in frequency, duration, and amplitude of reticular contractions measured manometrically. Total area of reticular contractions from physiographic tracings decreased 10.4 to 18.5%. Ruminal DM contents decreased 4.5 to 7.5%. Experiment 2 characterized the effects of casein on reticular contractions to be mediated by opioid peptides. Steers were infused abomasally (4 h) with either a 5% (wt/vol) solution of casein or its hydrolysate with or without a predose of naltrexone as an opiate antagonist (.5 mg/kg of BW) in a 2 x 2 factorial. Both casein and hydrolysate reduced frequency and duration of reticular contractions. Hydrolysate decreased contraction frequency within 30 min of infusion and 60 min prior to effects of casein. Naltrexone reversed the effects of casein and accentuated the effects of hydrolysate. Ruminal liquid outflow was decreased 19.7% with hydrolysate. Postruminal infusion of casein or its hydrolysate resulted in casomorphin-like activity on reticular motility and digesta passage.

Manipulation of gastrointestinal nutrient delivery in livestock

Discussed herein are the constraints of nutrient delivery from the gastrointestinal tract that are placed on postabsorptive synthetic processes in highly selected strains of domestic livestock or livestock treated with growth promotants exogenously or via transgenic manipulation. Emphasis is placed on the discussion of recent advances in the knowledge of the regulation and manipulation of digestion and the absorption by the intestinal epithelium. Slaframine, a muscarinic exocrine secretagogue with a high affinity for the gastrointestinal tract, and epidermal growth factor may have practical potential for the manipulation of digestion and absorption, respectively. Special consideration is given to energetic considerations that must accompany any manipulation of gastrointestinal function. Down-regulation and up-regulation of mechanisms must be equally considered as this area is explored further.

Dietary fat, protein degradability, and calving season: effects on nutrient use and performance of early lactation cows

Twelve multiparous Holstein cows calving in fall and 12 calving in summer were blocked into four groups and used in a 2 x 2 x 2 factorial to determine the effects of season of calving, dietary fat, and protein degradability on milk production and efficiency of NEL utilization in a 16-wk study. Blocks were assigned randomly to one of four dietary treatment combinations: 1) control concentrate plus soybean meal (high degradability protein supplement); 2) control concentrate plus a mixture of heated soybean meal and corn gluten meal (low degradability protein supplement); 3) a blend of the control concentrate and a concentrate containing 12.1% fat to provide 1 kg d-1 fat, plus soybean meal; and 4) concentrate as in diet 3 plus heated soybean meal and corn gluten meal. Nutrient intake, milk yield and composition, BW changes, and daily ambient temperature were monitored. Intake of DM appeared to be related to NDF intake but was not affected by fat, protein degradability, or calving season. Intake of NEL was increased by feeding fat. Digestabilities of DM and CP were increased and fiber was decreased by feeding fat. Percentage and yields of milk fat, SNF, and protein and 4% FCM production were higher in cows calving in fall. Milk fat percentage was low in all cows in the study. Efficiency of energy utilization for milk production was decreased in cows fed fat and calving in the summer and by low protein degradability during wk 5 to 8 of lactation. At high concentrate intake, calving season had more effect on milk production than level of fat or protein degradability.

Effects of additives and growth environment on preservation and digestibility of wheat silage fed to Holstein heifers

Wheat grown in two separate years under different environmental conditions was fed as silage to investigate effects of additives on forage preservation and digestibility. Direct-cut wheat was harvested in an early head stage of maturity. Wheat was drought stressed in yr 1 and averaged 41.6% DM, and yr 2 averaged 23.0% DM at harvest. Forage was ensiled in 10 900-kg concrete stave silos; 2 per year were assigned to one of five treatments consisting of control, treatment with an enzyme-chemical product, or treatment with one of three different types of lactic acid bacterial inoculants. Each year, during two 12-d periods, forage from five different silos was fed individually for ad libitum intake, separate from concentrate (1.1% of BW) to 15 Holstein heifers (average BW 228 +/- 32 kg). Wheat forage and silage from yr 1 was lower in CP but higher in NDF, ADF, lignin, and starch than that harvested in yr 2. Silage additives decreased DM and NDF recovery in yr 1 and increased DM, NDF, and neutral detergent solubles recovery in yr 2. Additives increased the ratio of lactic to acetic acid and decreased ammonia in silage both years. Additives increased DM and fiber digestibilities of wheat silage-based rations fed to Holstein heifers in yr 2. In vitro digestibility indicated that these improvements were associated with a reduction in the lag phase of forage digestion. The rate of in vitro DM digestibility was positively correlated with silage DM recovery, suggesting an association with nutrient preservation. Wheat preservation and digestibility both were improved by silage additives when wheat was grown under normal environmental conditions, but losses were greater with additives in drought-stressed forage.