Selective decline of bacteria colonizing the calf hindgut during colostrum to milk transition, with persistence of taxa correlating with host passive immunity.

In neonate calves, the association between gut microbial colonization and passive immunity acquisition remains largely unknown. We evaluated the effect of transition from colostrum to milk on the hindgut microbiota, and the correlations between acquired passive immunity and this microbiome. In 14 Holstein calves, colostrum quality and host passive immunity were measured, feces were sampled when feeding colostrum and after transition to milk. Then, in eight calves displaying a wide range of passive immunity, the hindgut microbiota was evaluated with DNA sequencing; differential abundance was analyzed with Maaslin2. With transition from colostrum to milk, many initial bacterial colonizers did not survive; genus Ralstonia decreased, but Lactobacillus and Bacteroides increased. When feeding colostrum, the amount of immunoglobulins consumed positively correlated with abundance of Lactobacillaceae and Lachnospiraceae, but Escherichia-Shigella and Clostridium sensu stricto 1 correlated negatively with host passive immunity. After transition to milk, acquired passive immunity negatively correlated with Clostridium sensu stricto 1, Ralstonia, and Veillonella. Overall, many initial hindgut colonizers did not thrive during transition from colostrum to milk, homogenizing the bacterial profile with prevalence of milk digesters. Several bacterial taxa showed strong correlation with host passive immunity, suggesting an interplay between calf passive immunity acquisition and the colonizing microbiota.

Effect of Supranutritional Dosage Selenium in Neonatal Goat Kids on Productive Performance, Physicochemical Profiles in Meat, Selenium Levels in Tissues, and Histopathological Findings.

Selenium (Se) is an essential element and antioxidant that catalyzes the destruction of hydrogen peroxide formed during cellular oxidative metabolism. Doses of Se as selenomethionine (SeMe) by oral route are 0.1-0.3 mgSe/kg DM, while the dose by parenteral route with sodium selenite (Na2SeO3) is 0.1 mgSe/BW. The effects of supranutritional Se supplementation on normal kids have rarely been studied. The objective of the study was to evaluate both Se sources on growth performance, Se in tissues, histopathological findings, and meat characteristics. Forty-five kids of the Pastoreña breed with 25-day age were distributed (4.7 ± 1.13 kg) in three treatments: a) control group, C: consumption with goat milk (GM: containing 0.135 mgSe/g); b) NaSe: GM plus Na2SeO3 injectable, 0.25 mgSe/kg BW; c) SeMe: GM plus oral dosage, 0.3 mgSe as SeMe daily. Fifteen animals per treatment were slaughtered at 7, 14, and 21 days. Feed conversion improved (P < 0.05) with Se supplement (P < 0.05) at 7 and 14 days. SeMe had higher protein and fat meat content (P < 0.05). SeMe increased Se liver at 14 and 21 days. NaSe and SeMe had higher (P < 0.05) levels of Se kidney. SeMe-21d showed 42% mononuclear and periportal cell infiltration lesions. In conclusion, Se administered through milk in goat kids was insufficient to prevent nutritional muscular dystrophy. The supranutritional dose of 0.25 mg/kg as NaSe was sufficient to maintain the Se level in tissues. SeMe increased Se liver and kidney efficiently. Both Se sources improved the bioavailability of the mineral in kids.