Biology subjects

Caton, J.

Publications and source records attributed to Caton, J..

2 recordsLinked to original sources

bioRxiv2021

Characterization of the microbiota associated with 12-week-old bovine fetuses exposed to divergent in utero nutrition

A recent study reported the existence of a diverse microbiota in 5-to-7-month-old calf fetuses, suggesting that colonization of the bovine gut with so-called "pioneer" microbiota may begin during mid-gestation. In the present study, we investigated 1) the presence of microbiota in bovine fetuses at early gestation (12 weeks), and 2) whether the fetal microbiota is influenced by the maternal rate of gain or dietary supplementation with vitamins and minerals (VTM) during early gestation. Amniotic and allantoic fluids, and intestinal and placental (cotyledon) tissue samples obtained from fetuses (n = 33) on day 83 of gestation were processed for the assessment of fetal microbiota using 16S rRNA gene sequencing. The sequencing results revealed that a diverse and complex microbial community was present in each of these fetal compartments evaluated. Allantoic and amniotic fluids, and fetal intestinal and placenta microbiota each had distinctly different (0.047 [≥] R2 [≥] 0.019, P [≤] 0.031) microbial community structures. Allantoic fluid had a greater (P < 0.05) microbial richness (number of OTUs) (Mean 122) compared to amniotic fluid (84), intestine (63) and placenta (66). Microbial diversity (Shannon index) was similar for the intestinal and placental samples, and both were less diverse compared with fetal fluid microbiota (P < 0.05). Thirty-nine different archaeal and bacterial phyla were detected across all fetal samples, with Proteobacteria (55%), Firmicutes (16.2%), Acidobacteriota (13.6%) and Bacteroidota (5%) predominating. Among the 20 most relatively abundant bacterial genera, Acidovorax, Acinetobacter, Brucella, Corynebacterium, Enterococcus, Exiguobacterium and Stenotrophomonas differed by fetal sample type (P < 0.05). A total of 55 taxa were shared among the four different microbial communities. qPCR of bacteria in the intestine and placenta samples as well as scanning electron microscopy imaging of fetal fluids provided additional evidence for the presence of a microbiota in these samples. Minor effects of maternal rate of gain and VTM supplementation, and their interactions on microbial richness and composition were detected. Overall, the results of this study indicate that colonization with pioneer microbiota may occur during early gestation in bovine fetuses, and that that the maternal nutritional regime during gestation may influence the early fetal microbiota.

microbiology↗

bioRxiv2020

Digestive parameters during gestation of Holstein heifers

Our objective was to estimate nutrient intake, ruminal flow, total apparent and ruminal digestibility, rates of passage and digestion, ruminal and omasal pH, blood metabolite concentrations, and body measurements during gestation of Holstein heifers. Eleven pregnant Holstein heifers, 8 of which fitted with a rumen cannula (450 {+/-} 27.6 kg of body weight and 20 {+/-} 3.5 months of initial age) were used. All heifers received the same diet composed of corn silage, soybean meal, corn meal, minerals and vitamins, with a corn silage:concentrate ratio of 50:50 (on a dry matter basis), aiming an average daily gain of approximately 1.0 kg. The sampling periods were established according to the days of gestation: 145, 200, and 255 with a duration of 10 days per period. Total fecal samples were collected to estimate dry matter, organic matter, crude protein, and neutral detergent fiber digestibility. Blood samples were collected to analyze metabolites (non-esterified fatty acids, {beta}-hydroxybutyrate, urea, and glucose). Data were analyzed as a repeated measurements scheme, using MIXED procedure, with differences declared when P < 0.05. Dry matter intake expressed in kg/day increased from d-145 to d-200, and remaining stable until d-255 of gestation. The same results were observed for organic matter and crude protein intake, increasing 15.0 and 35.8% respectively. In contrast, when dry matter intake was evaluated as % body weight, we observed a decrease of 16.7% from d-200 to d-255. Days of gestation did not influence ruminal flow of dry matter, organic matter, crude protein, and neutral detergent fiber. We observed an increase in the ruminal digestibility of neutral detergent fiber by 20.5%. The apparent total-tract digestibility of dry matter, organic matter, and crude protein changed over days of gestation, with an increase of 11.9, 8.5, and 9.8%, respectively, when comparing d-145 with d-200. The rate of digestion of neutral detergent fiber increased from 2.0 to 3.5% h-1. Glucose levels decreased, while {beta}-hydroxybutirate and non-esterified fatty acids increased from d-145 to d-255. In conclusion, our results demonstrate a reduction in dry matter intake in % body weight due to pregnancy. It also shows an increase in total apparent digestibility through gestation, which imply a greater efficiency of use of nutrients by pregnant animals. Thus, further research is still needed to consolidate such results and to elucidate the mechanism about nutrient usage during the final third of gestation in heifers.

physiology↗