Passage through the rumen and the large intestine of sheep estimated from faecal marker excretion curves and slaughter trials

An Early Treatment With BKI-1748 Exhibits Full Protection Against Abortion and Congenital Infection in Sheep Experimentally Infected With Toxoplasma gondii

Congenital toxoplasmosis in humans and in other mammalian species, such as small ruminants, is a well-known cause of abortion and fetal malformations. The calcium-dependent protein kinase 1 (CDPK1) inhibitor BKI-1748 has shown a promising safety profile for its use in humans and a good efficacy against Toxoplasma gondii infection in vitro and in mouse models. Ten doses of BKI-1748 given every other day orally in sheep at 15 mg/kg did not show systemic or pregnancy-related toxicity. In sheep experimentally infected at 90 days of pregnancy with 1000 TgShSp1 oocysts, the BKI-1748 treatment administered from 48 hours after infection led to complete protection against abortion and congenital infection. In addition, compared to infected/untreated sheep, treated sheep showed a drastically lower rectal temperature increase and none showed IgG seroconversion throughout the study. In conclusion, BKI-1748 treatment in pregnant sheep starting at 48 hours after infection was fully effective against congenital toxoplasmosis.

Does Replacing Maize with Barley Affect the Animal Performance and Rumen Fermentation, including Methane Production, of Beef Cattle Fed High-Concentrate Diets On-Farm?

Ruminants fed high-concentrate diets produce less enteric methane than those fed high-forage diets, but not all grains are equally effective in reducing methane production. This study aimed to examine, in farm conditions, the effects of a partial substitution of maize with barley on animal performance and rumen fermentation, including methane production, of intensively reared beef calves (ca. 0.9:0.1 concentrate to forage ratio). Ninety-six beef calves were fed a concentrate with 45.5% maize and 15% barley (n = 48; M) or a concentrate with 15.5% maize and 45% barley (n = 48; B). Both the concentrate and barley straw were offered ad libitum. The type of concentrate did not have a significant effect (p > 0.05) on final live weight, average daily gain, carcass dressing percentage or intake of concentrate and straw. Dry matter and organic matter digestibility were higher (p < 0.05) for the M (75.4% and 76.6%) than for the B (71.0% and 73.1%) treatment, but with no effect on digestible organic matter intake. In general, the majority cereal in the concentrate did not affect rumen fermentation, including methane production, or the degradability of dry matter and starch. A partial substitution of maize with barley in the concentrate offered to beef calves does not seem a promising strategy to decrease the emissions of enteric methane on-farm.

Gut region induces gastrointestinal microbiota community shift in Ujimqin sheep (Ovis aries): from a multi-domain perspective

Gastrointestinal (GI) microbiota is one of the most complicated microbial ecosystems and is vital in regulating biological processes associated with nutrient absorption and homeostatic maintenance. Although several efforts have been achieved in characterizing bacterial communities across gut regions, the variation of non-bacterial communities across GI tracts is still largely unexplored. To address this, we investigated microbial biogeography throughout the whole GI tracts of Ujimqin sheep (Ovis aries) by amplicon sequencing which targeted bacteria, fungi, and archaea. The results indicated that the community structures of all three domains were significantly distinguished according to GI tracts (stomach, small intestine, and large intestine), and a more strong and efficient species interaction was detected in small intestine based on cross-domain network analysis. Moreover, a between-domain difference in microbial assembly mechanism of among-GI regions was revealed here, wherein bacterial community is dominantly governed by variable selection (explaining ~62% of taxa turnover), while fungal and archaeal communities mainly governed by homogenizing dispersal (explaining ~49% and 60% of the turnover, respectively). Overall, these data highlight the GI section- and domain-dependence of GI microbial structure and assembly mechanism, suggesting that multi-domain should be explicitly considered when evaluating the influences of GI selection on gut microbial communities.

Trichostrongylus colubriformis infection: Impact on digesta passage rate and lamb performance

In this study we aimed to evaluate the effect of Trichostrongylus colubriformis infection on digesta passage rate, rumen fermentation and lamb performance. Eighteen three-month-old Santa Ines castrated male lambs (16.9 ± 1.43 kg of body weight) were randomly distributed in two experimental treatments: Infected with T. colubriformis (I, n = 9) and Uninfected (U, n = 9). The I lambs received a total of 45,000 L₃ larvae of T. colubriformis (5,000 infective larvae, three times per week for three weeks). Daily feed intake was assessed using the I lambs as a reference for their respective pairs on the U group (pair-fed). Weight, body condition score and faeces (stool) samples were obtained every 15 days for 75 days. In both treatments, faecal egg count (FEC), digesta passage rate, rumen fermentation parameters, protozoa count and short chain fatty acids (SCFA) were evaluated. The lambs presented moderate infection (FEC = 620). The retention time of the digesta in the rumen-reticulum segment was lower (P < 0.05) in I lambs. The I lambs presented no inappetence, however, lower concentrations of total SCFA and butyrate, while higher acetate concentration were observed in these lambs (P < 0.05). The present findings highlight that T. colubriformis infection decreased the retention time (solid and liquid content) of the digesta in the rumen-reticulum, as well as negatively affected lamb growth.

Stable isotope-labelled feed nutrients to assess nutrient-specific feed passage kinetics in ruminants

Knowledge of digesta passage kinetics in ruminants is essential to predict nutrient supply to the animal in relation to optimal animal performance, environmental pollution and animal health. Fractional passage rates (FPR) of feed are widely used in modern feed evaluation systems and mechanistic rumen models, but data on nutrient-specific FPR are scarce. Such models generally rely on conventional external marker techniques, which do not always describe digesta passage kinetics in a satisfactory manner. Here the use of stable isotope-labelled dietary nutrients as a promising novel tool to assess nutrient-specific passage kinetics is discussed. Some major limitations of this technique include a potential marker migration, a poor isotope distribution in the labelled feed and a differential disappearance rate of isotopes upon microbial fermentation in non-steady state conditions. Such limitations can often be circumvented by using intrinsically stable isotope-labelled plant material. Data are limited but indicate that external particulate markers overestimate rumen FPR of plant fibre compared with the internal stable isotope markers. Stable isotopes undergo the same digestive mechanism as the labelled feed components and are thus of particular interest to specifically measure passage kinetics of digestible dietary nutrients.