The aim of this study was to evaluate how the inclusion of a blend of essential oils in milk replacer (MR) affects different outcomes of dairy heifers. The outcomes evaluated: feed intake, performance, body development, blood cells and metabolites, insulin-like growth factor-1 (IGF-1), rumen fermentation, fecal scores, and respiratory scores. All outcomes were evaluated during pre-weaning (4–60 d of age), and carry-over effects during post-weaning (61–90 d of age) periods. The experimental units utilized were 29 newborn Holstein × Gyr crossbred dairy heifers, with genetic composition of 5/8 or more Holstein and 3/8 or less Gyr and body weight (BW) at birth of 32.2 ± 5.2 kg. Experimental units were assigned to either a control (CON, n = 15) or a blend of essential oil supplementation (BEO, n = 14) treatment, maintaining a balance of genetic composition. The BEO was supplemented in the MR with 1 g/d/calf of a blend of essential oils (Apex Calf, Adisseo, China) composed by plant extracts derived from anise, cinnamon, garlic, rosemary, and thyme. During the pre-weaning phase, all heifers were fed 5 L of MR/d reconstituted to 15% (dry matter basis), divided into two equal meals. Water and starter were providedad libitum. During the post-weaning, animals received a maximum of 3 kg of starter/d, andad libitumcorn silage, divided into two meals. Feed intake, fecal and respiratory scores were evaluated daily. The BW was measured every three days, while body development was recorded weekly. Blood samples were collected on 0, 30, and 60 d of age for total blood cell count, weekly and on the weaning day to determinate ß-hydroxybutyrate, urea and glucose, and biweekly for IGF-1. Ruminal parameters (pH, volatile fatty acids, ammonia-N, and acetate:propionate proportion—C2:C3) were measured on days 14, 28, 42, 60, 74 and 90. A randomized complete block design with an interaction between treatment and week was the experimental method of choice to test the hypothesis of the BEO’s effect on all outcomes. An ANOVA procedure was used for continuous outcomes, and a non-parametric test was used for the ordered categorical outcomes, both adopting a CI = 95%. Results indicated that there was not enough evidence to accept the alternative hypothesis of the effect of BEO in MR on feed intake, performance, body development, and blood metabolites during both pre-weaning and post-weaning periods. However, results indicated that the inclusion of BEO in MR significantly affects the proportion of C2:C3 during pre- and post-weaning (P= 0.05). Similarly, the effect was significant for basophil (P≤ 0.001), and platelet (P= 0.04) counts pre-weaning. The interaction between week and treatment was also significant for lymphocytes (P≤ 0.001), revealing a cumulative effect. Lastly, fecal scores were also significant (P= 0.04) during pre-weaning, with lower values for BEO. The BEO contributed to ruminal manipulation in pre-weaning and carry-over effects in post-weaning, immunity improvement, and decreased morbidity of neonatal diarrhea in the pre-weaning phase.

This study investigates the effects of heat stress in a climate chamber from day 0 to 28 days of life on physiological responses, intake, nutrient digestibility, immunity, and performance in neonatal Holstein calves. Thirty-four calves (nineteen females, fifteen males) were randomly assigned to a control group (CON, temperature–humidity index [THI] 66, with 22 °C and 65% humidity for 24 h, n = 17) or a heat-stressed (HS) group, which was exposed to a THI of 82, 32 °C, and 65% humidity for 9 h, followed by a THI of 66, 22 °C, and 65% humidity for 15 h. The HS calves exhibited increased respiratory rates and rectal temperatures (p < 0.001), particularly during heat exposure periods, as well as a 59.5% increase in water intake compared to CON. While milk and solid feed intake, average daily gain, and feed efficiency were similar between groups, HS calves had reduced ether extract digestibility and altered ruminal fermentation, including lower acetate and lower propionate concentrations. The blood cytokine analysis showed elevated interleukin-4 and reduced interleukin-8 and IP-10 levels in heat-stressed calves, indicating a shift toward an anti-inflammatory immune profile. Despite no major performance impairments, heat stress has induced clear physiological, digestive, and immunological changes. These results underscore the importance of implementing thermal mitigation strategies during early life to safeguard calf health and development in increasingly warmer climates.

Industrialization of the Babassu coconut for edible oil production generates many co-products and has great potential to be used in ruminant nutrition. The aim of this study was to evaluate the effect of different inclusions of endocarp meal type II of Babassu coconut (BEMII) on intake and digestibility of sheep diets. Twenty non-castrated male sheep with an undefined breed were distributed in a completely randomized design with four treatments and five replications. The animals received an experimental diet with increasing inclusions of BEMII (0.0%, 7.5%, 15.0%, and 22.5%). Increasing additions of the coproduct negatively influenced dry matter intake (g/BW and g/kg0.75). Crude protein intake (in grams) per day decreased linearly with the inclusion of BEMII, presenting a reduction of 49.35 g/d. The inclusion of 7.5% showed the best response for energy balance among all inclusions and presented the closest nitrogen balance value when compared to the control group; therefore, this inclusion percentage is the best for endocarp meal utilization.

Diarrhea and respiratory diseases pose significant challenges in the rearing of pre-weaned calves, motivating the investigation of tools to improve gastrointestinal tract development, health, and overall performance in young calves. Consequently, the primary objective of this study was to assess the effectiveness of an additive incorporated into milk replacer to promote the development and health of the animals. Forty-six dairy calves were randomly assigned into two treatments: control (CON, n = 23; with 15 females and 8 males), and sodium butyrate (SB, n = 23; with 15 females and 8 males). The calves in the SB treatment group were supplemented with 4 g/d of unprotected sodium butyrate (Adimix, Adisseo, China), added to the milk replacer from 4 to 60 days of age. Water and starter were fed ad libitum. The study evaluated several parameters, including feed intake, nutrient digestibility, ruminal pH, ammonia and volatile fatty acids, blood metabolites (glucose, insulin-like growth factor type 1, urea, β–hydroxybutyrate), hemogram, health scores, performance, and feed efficiency. Bull calves were euthanized at 60 days of age for organ comparison, while heifer calves were assessed for carryover effects up to 90 days of age. Data were analyzed independently using linear mixed models using the nlme package in R, and the Artools package for non-parametric categorical outcomes. Although the feed intake and performance variables exhibited differences within weeks, no divergence was observed between treatment groups. Notably, a positive treatment-by-week interaction was identified for starter feed intake (p = 0.02) and total dry matter intake (p = 0.04) during pre-weaning for CON animals. Ruminal parameters, blood metabolites, and hemogram values such as glucose, urea, insulin-like growth factor type 1, mean corpuscular value, lymphocytes, and neutrophils displayed differences within weeks during the pre-weaning stage, but similar results within groups. No differences between supplemented and non-supplemented calves were found across nutrient digestibility, organ development, and histology. Regarding health scores, differences were noted within weeks for fecal and respiratory scores during the pre-weaning stage, and only the respiratory score during the post-weaning stage. Consequently, butyrate supplementation did not elicit improvements or negative effects in the body development or health status of dairy calves.

The transition to lactation demands a substantial amount of calcium (Ca) to support colostrum and milk production. Extensive research has been focused on elucidating the interplay between the traditional Ca-parathyroid hormone-vitamin D axis and mammary- derived factors, such as serotonin (5-HT) and parathyroid-hormone-like hormone (PTHLH), in regulating Ca metabolism during the transition period. Here, we investigate the impact of induced subclinical hypocalcemia (SCH) on 5-HT and parathyroid hormone (PTH) concentrations in early-lactation dairy cows under conditions of 24-h milk stasis. Twelve multiparous Holstein cows in early lactation received either continuous intravenous infusion of saline solution or 5% ethylene glycol tetraacetic acid (EGTA) to maintain blood ionized calcium (iCa) below 1 mM(n = 6/treatment). Blood samples were collected hourly during infusion and 4, 8, 12, 24, and 48 h post- infusion. Urine samples were collected every 4 h during infusion and at 12, 24, and 48 h post-infusion, and milk samples were collected daily from 2 d pre-infusion to 4 d post-infusion. Infusion of EGTA resulted in decreased blood iCa during the infusion period, with iCa concentrations rebounding 24 h post-infusion. No significant treatment effects were observed on 5-HT and PTH blood concentrations. These findings underscore the importance of considering physiological distinctions in studies of Ca metabolism during the transition period.