Ruminal histamine, lactate and animal performance

Effects of a moderate transition from 70% to 90% concentrate diet on early alterations in feeding behavior, rumen environment, reticulorumen motility, and blood acid–base status in beef heifers

The objective of this study was to determine the early responses to a moderate concentrate increase in cattle diets with regards to various behavioral and physiological responses in cattle. Eight ruminally cannulated Angus crossbred beef heifers were adapted to a 70% concentrate diet (T70) and then switched to a 90% concentrate diet (H90). Measurements of feeding behavior, ruminal pH and temperature, rumen motility, liquid passage rate, and blood acid–base status were conducted on T70 as well as first day (d1) and second day (d2) of high-grain H90feeding to monitor the beginning of the transition period. Ruminal pH was below 5.6 for longer on both days of H90 compared with T70, suggesting animals experienced subacute ruminal acidosis while switching from T70 to H90. Transitioning did not affect dry matter intake (DMI). Eating rate during meals was reduced on d1 and d2 H90 compared with T70. Ruminal contraction amplitude was reduced on both days of H90 feeding. Contraction duration was reduced on d1 H90, and returned to T70 values by d2 H90. Results indicated that a moderate transition to a finishing diet influenced feeding behavior and reduced rumen motility at the beginning time after transition, but did not influence voluntary DMI.

Histamine activates inflammatory response and depresses casein synthesis in mammary gland of dairy cows during SARA

Background

Mounting evidences observed that subacute ruminal acidosis (SARA) induced by high concentration (HC) diet increases the translocation of histamine from digestive tract into circulation causing a diverse of diseases in dairy cows. However, it is largely unknown how it does affect the function of mammary gland and milk quality. Hence, this study aims to observe the effects of histamine derived from the digestive tract on the inflammatory response and casein synthesis in the mammary glands during SARA. Twelve cows fitted rumen fistula were randomly divided into either control group administrated low concentration (LC) diet (60% forage, n = 6) or treatment group administrated HC diet (40% forage, n = 6) for 18 weeks.

Results

Our data showed that HC diet resulted in significant declines in rumen pH value, milk yield and milk quality, as well as longer duration of averaged pH value below 5.6 per day (more than 180 min) compared to LC diet, these findings confirmed SARA occurence. Our study also observed that SARA increased the content of histamine in rumen fluid, plasma, liver and mammary gland, and enhanced the mRNA expression of histamine specific receptor in the mammary gland. Additionally, we found that the mRNA expression of inflammatory response genes in mammary glands was increased, which was consistent with the protein expression results, showing that the protein kinase C(PKC) / nuclear factor kappa B (NF-κB) or protein kinase A (PKA) / NF-κB signalling pathways of the inflammatory response were activated. The mRNA expression of mTOR, P70S6K and αS1 in mammary glands were significantly decreased with the protein expression of mTOR, P70S6K and αS1-casein, and the phosphorylation levels of the mTOR and P70S6K proteins were also decreased.

Conclusions

Our study showed that the milk protein of lactating cows is depressed after long-term feeding of HC at the individual level, which was paralleled at the gene and protein levels. The inflammatory response in mammary gland caused by histamine derived from the digestive tract is related to the decline of casein synthesis. Our findings point to a new link between the inflammatory response and casein synthesis, but the understanding of the molecular mechanisms involved in this process will require further research.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1491-3) contains supplementary material, which is available to authorized users.

Ruminal acidosis in beef cattle: the current microbiological and nutritional outlook

Ruminal acidosis continues to be a common ruminal digestive disorder in beef cattle and can lead to marked reductions in cattle performance. Ruminal acidosis or increased accumulation of organic acids in the rumen reflects imbalance between microbial production, microbial utilization, and ruminal absorption of organic acids. The severity of acidosis, generally related to the amount, frequency, and duration of grain feeding, varies from acute acidosis due to lactic acid accumulation, to subacute acidosis due to accumulation of volatile fatty acids in the rumen. Ruminal microbial changes associated with acidosis are reflective of increased availability of fermentable substrates and subsequent accumulation of organic acids. Microbial changes in the rumen associated with acute acidosis have been well documented. Microbial changes in subacute acidosis resemble those observed during adaptation to grain feeding and have not been well documented. The decrease in ciliated protozoal population is a common feature of both forms of acidosis and may be a good microbial indicator of an acidotic rumen. Other microbial factors, such as endotoxin and histamine, are thought to contribute to the systemic effects of acidosis. Various models have been developed to assess the effects of variation in feed intake, dietary roughage amount and source, dietary grain amount and processing, step-up regimen, dietary addition of fibrous byproducts, and feed additives. Models have been developed to study effects of management considerations on acidosis in cattle previously adapted to grain-based diets. Although these models have provided useful information related to ruminal acidosis, many are inadequate for detecting responses to treatment due to inadequate replication, low feed intakes by the experimental cattle that can limit the expression of acidosis, and the feeding of cattle individually, which reduces experimental variation but limits the ability of researchers to extrapolate the data to cattle performing at industry standards. Optimal model systems for assessing effects of various management and nutritional strategies on ruminal acidosis will require technologies that allow feed intake patterns, ruminal conditions, and animal health and performance to be measured simultaneously in a large number of cattle managed under conditions similar to commercial feed yards. Such data could provide valuable insight into the true extent to which acidosis affects cattle performance.

Acidosis in Feedlot Cattle

Mortality from digestive diseases in feedlot cattle is second only to that from respiratory diseases. Acidosis is a major digestive disorder and is likely to continue because of ongoing attempts to improve the efficiency of beef production by feeding more grain and less roughage. Subacute acidosis is the most prevalent form of acidosis in feedlots but is difficult to diagnose because of the absence of overt clinical signs. Control of acidosis is achieved largely by sound nutritional management. No single strategy or solution exists; however, an effective management strategy should factor in dietary formulation, a consistent feeding program, prudent bunk management, use of nonstarch by-products, and feed additives to minimize pen-to-pen and animal-to-animal variations in feed intake.

Effect of rapid or gradual grain adaptation on subacute acidosis and feed intake by feedlot cattle1,2

The effects of grain adaptation protocol on subacute acidosis and feed intake by cattle were studied in a completely randomized experiment using 12 crossbred heifers (384 +/- 25 kg BW). The dietary proportion of concentrate was increased from 40 to 90% (DM basis) either by rapid adaptation (65% concentrate diet fed for 3 d) or by gradual adaptation (five intermediate diets containing 48.3, 56.7, 65.0, 73.3, and 81.7% concentrate, fed for 3 d each). Feed intake and ruminal pH (by indwelling ruminal electrodes) were monitored over 20 d. Mean daily pH variables did not differ (P > or = 0.10) between treatments on any of the 3 or 4 d that 65 or 90% concentrate was fed. Variances of a number of pH variables were greater (P < 0.05) for rapidly adapted heifers than for those on the gradual adaptation protocol during adaptation to 65 and 90% concentrate. Mean hourly pH did not differ over the first 24 h of adaptation to 65% concentrate, but variance of hourly pH tended (P < 0.10) to be greater for rapidly adapted than for gradually adapted heifers for eight of the first 24 h. On the first day of feeding 90% concentrate, ruminal pH tended (P = 0.07) to be less at 11 and 12 h after feeding with rapid adaptation than with gradual adaptation. Variance of hourly pH increased steadily in rapidly adapted heifers from 6 h after feeding onward. Ruminal VFA concentration and osmolality did not differ between treatments. Ruminal lactate concentration was < 1 mM, except in two rapidly adapted heifers and one gradually adapted heifer after introduction to 90% concentrate. Adaptation method did not affect DMI or day-to-day variation in DMI. Detection of acidosis was associated with increased variance in ruminal pH variables. A range of individual responses to grain challenge was observed, but current management strategies for preventing acidosis in pens of cattle are based on responses of the most susceptible individuals. A better understanding of factors governing individual responses to acidotic challenge may allow for the development of more effective acidosis prevention practices.

Histamine affects growth of sheep ruminal epithelial cells kept in primary culture

Ten, 100 and 1000 microM histamine were applied to ruminal epithelial cells in primary culture. Each of these concentrations diminished cell count as well as the protein and DNA contents of cultures by approximately 20%. On Pappenheim staining, reduced cell count was predominantly attributable to a decrease in relatively chromophobic cells. It is concluded that histamine either induces apoptosis, or increases cell shedding, or interferes with mitosis and cell maturation. Each of these three possibilities implies that histamine may disturb epithelial regeneration after ruminal lactic acidosis.

Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers

A 4 x 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.

Investigation of the possible role of endotoxin, TXA2, PGI2 and PGE2 in experimentally induced rumen acidosis in cattle

Rumen acidosis was induced experimentally with 70 g barley/kg b.w. in 2 rumen fistulated cows. The cows were followed for 80 h after the grain engorgement. Endotoxin was monitored in cell-free ruminal fluid and peripheral plasma together with inflammation mediators TXA2, PGI2 and PGE2 and several clinical and clinical-chemical parameters. The results do not support the theory of systemical endotoxemia due to a large increase in rumen endotoxin concentration in cattle suffering from rumen acidosis. However, both clinical and clinical-chemical data suggest that an endotoxicosis developed, but the levels of inflammation mediators TXB2, FGI2 and PGE2 were not significantly elevated in the peripheral circulation. An absorbtion of endotoxins and synthesis of inflammation mediators are therefore suggested to take place prehepatically.