The objective of this study was to evaluate the addition of cane molasses during a 60 day dry period on performance and metabolism of Holstein cows during prepartum and postpartum periods. For experiment 1, 26 primiparous and 28 multiparous cows were used. Upon freshening, all cows were offered a common lactation diet. For experiment 2, six multiparous cows fitted with rumen cannulas were used to measure performance and metabolism, following the same protocol as experiment 1. Ruminal propionate increased by 10% during both prepartum and postpartum periods; however, papillae area was greater for cows not fed molasses, and volatile fatty acids (VFA) absorption from the rumen was not increased, resulting in similar glucagon-like-peptide-2 receptor (GLP-2R) density. The improved dry matter intake, when molasses was added into prepartum diets, translated into increased milk yield and energy-corrected milk (ECM) in Experiment 1 only for multiparous cows. For experiment 2, the improvement on milk performance was also observed, where cows fed molasses had 18.5% greater ECM production. Feeding molasses during a 60 day dry period positively influenced transition cow performance, and it was not accompanied by changes in rumen morphometrics; however, this indicates enhanced adaptation by the rumen epithelium based on similar capabilities for VFA absorption.

The objective of this study was to determine the effect of 5 and 10 d low feed intake (LF) on the ruminant gastrointestinal tract (GIT). Twelve rams and nine wethers were used in a randomized complete block design where they were blocked by castration status and BW. After 5 d of ad libitum feeding, lambs were either exposed to 0 (CON; 100% DMI; n = 7), 5 (LF5; 30% DMI; n = 7), or 10 d (LF10; 30% DMI; n = 7) of LF. At the end of the study, lambs were euthanized, the GIT was removed to determine the digesta and tissue weights by region and the weights of the liver, spleen, and kidneys were recorded. There were no castration × treatment interactions (P ≥ 0.32). Initial (P = 0.97) and final (P = 0.19) BW did not differ by treatment. The weight of the reticulo-ruminal tissue tended to be less (P = 0.06) for LF10 than CON, with LF5 being intermediate but not different. Ruminal digesta weight was not affected (P = 0.98). Omasal tissue weight did not differ among treatments (P = 0.24), but digesta weight tended (P = 0.07) to be greater for CON compared with LF10 and LF5. Abomasal tissue weight was reduced for LF10 (P = 0.04), with LF5 being intermediate but not different. Abomasal digesta weight was less for LF5 and LF10 than CON (P = 0.04). The weight of the duodenum tended (P = 0.08) to be greater for CON than LF10 and LF5, but digesta weight was not affected (P = 0.16). For the jejunum, tissue and digesta weight tended (P = 0.07) to be greater for CON than LF10, with LF5 being intermediate. The weight of the ileum tended to be the greatest for CON, intermediate for LF5, and the least for LF10 (P = 0.10), but digesta weight was not affected (P = 0.81). Cecal tissue weight was not affected by treatment (P = 0.89); whereas digesta weight was the greatest (P = 0.03) for LF10, the least for CON, and intermediate but not different for LF5. In contrast, colonic tissue weight was less for LF10 relative to LF5 and CON (P = 0.01) and digesta weight tended (P = 0.05) to be greater for CON than LF5 and LF10. Liver weight was reduced (P < 0.01) for both LF5 and LF10 relative to CON, but kidney and spleen weights were not affected (P ≥ 0.33). This study indicates that exposing ruminants to LF rapidly reduces the weights for regions of the GIT and liver. These changes likely implicate a reduced absorptive capacity of the GIT and a lesser metabolic capacity of the liver.

Feedlot cattle produce high concentrations of short-chain fatty acids (SCFAs) through ruminal fermentation, with butyrate playing a crucial role in epithelial development and SCFA absorption. This study evaluated the effects of dietary sodium butyrate or exogenous fibrolytic enzymes on the ruminal epithelium and microbiota. Three rumen-cannulated Aberdeen Angus steers were assigned to a replicated 3 × 3 Latin square design, totaling six experimental periods. Each period lasted 28 d, comprising 14 d of adaptation and 14 d of finishing. Diets only differed in additive inclusion: CON—control; ENZ—exogenous enzyme complex (0.01% of the dry matter [DM]); BUT—sodium butyrate (0.3% DM during adaptation; 0.1% during finishing). The ENZ reduced the ruminal temperature (p = 0.04), and Diplodinium population (p = 0.03). The CON animals had greater lipopolysaccharide-binding protein concentration (p = 0.02). No treatment effects were observed for the alpha and beta diversity of bacterial communities, but shifts in abundance at the phylum level were detected for Bacteroidetes, Firmicutes, and Proteobacteria. Papillae dimensions were not significantly altered by treatments (p > 0.05). These findings suggest that while BUT and ENZ have some influence on the ruminal environment, their effects at the tested doses were limited, indicating the need for further studies with varying doses or combinations.

The objective of this study was to investigate the potential carryover effect of narasin (NAR) supplementation during the backgrounding phase on subsequent feedlot performance and gastrointestinal morphometrics of finishing Nellore bulls. Ninety-six bulls were used in a 2 × 2 factorial design, evaluating conditional NAR supplementation on the backgrounding phase (control [CON] or NAR) and finishing supplementation (sodium monensin [MON] or NAR), resulting in four treatments as follows: 1) CON+MON, 2) CON+NAR, 3) NAR+MON, and 4) NAR+NAR. During the backgrounding phase, NAR-fed cattle showed reduced dry matter intake (DMI) expressed in kilograms and as a percentage (P≤0.03), however, it did not significantly affect final body weight (BW), average daily gain (ADG), or feed efficiency compared with the CON-fed cattle (P≥0.14). In the finishing phase, neither backgrounding nor finishing supplementation, nor their interaction, had significant effects on BW, ADG, DMI, feed efficiency, hot carcass weight, dressing percentage, or gastrointestinal morphometrics (P≥0.11). Relative to CON+NAR and NAR+MON, cattle fed NAR+NAR showed reduced fluctuation in DMI throughout the entire experiment (%; P≤0.02); however, fluctuations, even above 10% in some treatments, did not lead to reduced ADG or increased rumenitis incidence. We conclude that dietary supplementation with NAR did not enhance performance or gastrointestinal development in Nellore cattle during backgrounding or finishing, nor was a carryover effect observed between phases. Although NAR-fed cattle in the finishing phase performed similarly to those receiving monensin, the absence of a negative control limits interpretation, warranting further research on its role in stabilizing dry matter intake.

Sleep in cattle is a complex physiological state comprising non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, while drowsing represents an intermediate vigilance state between wakefulness and sleep. Research has progressed from invasive electrophysiological recordings to noninvasive polysomnography (PSG), behavioral assessment, accelerometry, and automated classification approaches. However, accurately identifying and quantifying vigilance states under production conditions remains challenging. This narrative review, based on 22 primary studies identified through searches of Web of Science, Scopus and Google Scholar, critically synthesizes current knowledge of sleep physiology in cattle, the approaches used to assess it, and the principal methodological limitations affecting interpretation of the available evidence. Cattle exhibit a polyphasic sleep pattern, with NREM generally accounting for the largest proportion of total sleep. However, reported sleep and drowsing durations vary considerably among studies, and these differences may reflect both biological variation and methodological factors. Drowsing is particularly difficult to characterize because its behavioral and physiological features overlap with quiet wakefulness and light sleep. Rumination represents an additional challenge because associated muscular activity can interfere with electrophysiological recordings and complicate vigilance-state classification. Behavioral observations and accelerometry provide scalable measures of resting and sleep-like behavior but cannot independently establish physiological sleep, whereas PSG provides greater physiological resolution while remaining susceptible to artifacts and practical constraints. Current evidence is insufficient to establish causal relationships between sleep variation and cattle health, welfare, or productive performance. Future research should improve physiological classification during overlapping behavioral states, better validate scalable monitoring approaches, and evaluate the functional consequences of sleep variation across diverse cattle populations and production conditions.