Bioavailability of rumen-protected histidine, lysine, and methionine assessed using different in vivo methods.

The objective of this experiment was to estimate the bioavailability (BA) of rumen-protected (RP) His, RPLys, and 2 RPMet products using 3 in vivo methods: area under the curve (AUC), plasma dose-response (PDR), and fecal free AA (FFAA) methods. We used 8 rumen-cannulated cows in a replicated 4 × 4 Latin square experiment with 16-d periods. Treatments were (1) abomasal infusion of water (control), (2) abomasal infusion of free His, Lys, and Met (FAA), (3) administration of RPHis + RPLys + RPMet1 (rumen-protected methionine protected with ethyl cellulose; RPAA1), and (4) administration of RPHis + RPLys + RPMet2 (rumen-protected methionine protected with a pH-sensitive polymer; RPAA2).

Feed additives for methane mitigation: Recommendations for testing enteric methane-mitigating feed additives in ruminant studies.

There is a need for rigorous and scientifically-based testing standards for existing and new enteric methane mitigation technologies, including antimethanogenic feed additives (AMFA). The current review provides guidelines for conducting and analyzing data from experiments with ruminants intended to test the antimethanogenic and production effects of feed additives. Recommendations include study design and statistical analysis of the data, dietary effects, associative effect of AMFA with other mitigation strategies, appropriate methods for measuring methane emissions, production and physiological responses to AMFA, and their effects on animal health and product quality.

Perspective: Enteric methane mitigation and its impact on livestock hydrogen emissions.

In a hydrogen-based economy future, hydrogen leakage is becoming an environmental concern. Ruminants naturally produce small amounts of hydrogen, which is emitted in the environment along with other fermentation gases, such as the GHG methane and carbon dioxide. Here, for the first time, we estimated hydrogen emissions from the global ruminant livestock at 527 kt/yr (95% CI: 399, 654), or about 3.

Effects of calcium and buffer sources on lactational performance, ruminal fermentation, nutrient digestibility, and metabolism of dairy cows.

The objective was to investigate the effects of calcium and rumen buffer sources on lactational performance, ruminal fermentation, enteric gas emissions, apparent total-tract digestibility of nutrients, and blood variables of lactating dairy cows. A replicated 3 × 3 Latin square design experiment was conducted with 9 primi- and 9 multiparous mid-lactation Holstein cows. Cows were fed the same basal diet, except for the inclusion (as % DMI) of the following minerals: (1) CON, 0.

Effects of dose, dietary nutrient composition, and supplementation period on the efficacy of methane mitigation strategies in dairy cows: A meta-analysis.

The objective of this meta-analysis was to quantify the potential of CH-mitigating strategies in dairy cattle when accounting for the effects of treatment dose, dietary nutrient composition, and supplementation period. Data from 218 studies with dairy cattle published between 1963 to 2022 were reviewed. Individual CH mitigation strategies selected for the analysis were algae (Asparagopsis spp.

Lactational performance and hematological effects of capsaicin supplementation in dairy cows: A meta-analysis.

A meta-analysis was performed to investigate the effects of capsaicin (CAP) on lactational performance and blood chemistry and cell counts in dairy cattle. The database comprised 11 peer-reviewed studies published between 2011 and 2024. The overall effect of CAP, challenge (e.

Separate offering of forages and concentrates to lactating dairy cows: Effects on lactational performance, enteric methane emission, and efficiency of nutrient utilization.

The objective was to evaluate the effects of separate offering of feed ingredients (SF) and frequency of concentrate feeding versus offering a TMR, on lactational performance, ruminal fermentation, enteric CH emissions, nutrient digestibility, N use efficiency, milk fatty acid profile, and blood variables in mid-lactation dairy cows. Twenty-four Holstein cows (12 primi- and 12 multiparous) averaging (±SD) 141 ± 35 DIM and 43 ± 6 kg/d of milk yield (MY) at the beginning of the study were used in a replicated 3 × 3 Latin square design experiment with 3 periods of 28 d each, composed of 7 d for adaptation to the diets, 11 d for estimation of net energy and metabolizable protein requirements, and 10 d for data and samples collection. Cows were grouped based on parity, DIM, and MY into 4 Latin squares.

Lactational performance, ruminal fermentation, and enteric gas emission of dairy cows fed an amylase-enabled corn silage in diets with different starch concentrations.

This study investigated the effects of feeding an amylase-enabled corn silage (ACS) on the performance and enteric gas emissions in lactating dairy cows. Following a 2-wk covariate period, 48 mid-lactation Holstein cows were assigned to 1 of 3 treatments in a 10-wk randomized complete block design experiment. Treatments were diets containing the same proportion of corn silage (40% of dietary DM) as follows: (1) a conventional hybrid corn silage control (CON), (2) ACS replacing the control silage (ADR), and (3) the ADR diet replacing soybean hulls with ground corn grain to achieve the same dietary starch concentration as CON (ASR).

Invited review: Advances in nutrition and feed additives to mitigate enteric methane emissions.

Methane, both enteric and from manure management, is the most important greenhouse gas from ruminant livestock, and its mitigation can deliver substantial decreases in the carbon footprint of animal products and potentially contribute to climate change mitigation. Although choices may be limited, certain feeding-related practices can substantially decrease livestock enteric CH emission. These practices can be generally classified into 2 categories: diet manipulation and feed additives.

A meta-analysis of methane-mitigation potential of feed additives evaluated in vitro.

A systematic literature review of in vitro studies was performed to identify methane (CH) mitigation interventions with a potential to reduce CH emission in vivo. Data from 277 peer-reviewed studies published between 1979 and 2018 were reviewed. Individual CH mitigation interventions were classified into 14 categories of feed additives based on their type, chemical composition, and mode of action.

Lactational performance, enteric methane emission, and nutrient utilization of dairy cows supplemented with botanicals.

The objective of this study was to evaluate lactational performance, enteric gas emissions, ruminal fermentation, nutrient use efficiency, milk fatty acid profile, and energy and inflammatory markers in blood of peak-lactation dairy cows fed diets supplemented with Capsicum oleoresin or a combination of Capsicum oleoresin and clove oil. A 10-wk randomized complete block design experiment was conducted with 18 primiparous and 30 multiparous Holstein cows. Cows were blocked based on parity, days in milk, and milk yield (MY), and randomly assigned to 1 of 3 treatments (16 cows/treatment): (1) basal diet (CON); (2) basal diet supplemented with 300 mg/cow per day of Capsicum oleoresin (CAP); and (3) basal diet supplemented with 300 mg/cow per day of a combination of Capsicum oleoresin and clove oil (CAPCO).

A meta-analysis of methane mitigation potential of feed additives evaluated in vitro.

A systematic literature review of in vitro studies was performed to identify methane (CH) mitigation interventions with a potential to reduce CH emission in vivo. Data from 277 peer-reviewed studies published between 1979 and 2018 were reviewed. Individual CH mitigation interventions were classified into 14 categories of feed additives based on their type, chemical composition, and mode of action.

Lactational performance, rumen fermentation, nutrient use efficiency, enteric methane emissions, and manure greenhouse gas-emitting potential in dairy cows fed a blend of essential oils.

The objective of this experiment was to investigate the effects of an essential oil (EO) blend on lactational performance, rumen fermentation, nutrient utilization, blood variables, enteric methane emissions and manure greenhouse gas-emitting potential in dairy cows. A randomized complete block design experiment was conducted with 26 primiparous and 22 multiparous Holstein cows. A 2-wk covariate and a 2-wk adaptation periods preceded a 10-wk experimental period used for data and sample collection.

Production effects of extruded soybean meal replacing canola meal in the diet of lactating dairy cows.

This study investigated the effects of extruded soybean meal (ESBM) in comparison with canola meal (CM) fed on an equivalent crude protein (CP) basis on lactational performance and ruminal fermentation of dairy cows. Following a 2-wk covariate period, 48 Holstein cows averaging (±SD): 146 ± 46 d in milk (DIM) and 43 ± 7 kg/d milk yield (MY) were assigned 1 of 2 treatment diets in a randomized complete block design experiment, which included a 2-wk period for dietary treatment adaptation before experimental data were collected. Following the adaptation period, samples and experimental data were collected for a total of 7 wk.

Microbial composition, rumen fermentation parameters, enteric methane emissions, and lactational performance of phenotypically high and low methane-emitting dairy cows.

This experiment was designed to investigate the relation of high and low methane-yield phenotypes with body weight (BW), dry matter intake (DMI), lactation performance, enteric CH emissions, and rumen fermentation parameters in lactating dairy cows. A total of 130 multi- and primiparous Holstein cows were screened for enteric CH emissions using the GreenFeed system (C-Lock Inc.).

Effects of ensiling time on corn silage starch ruminal degradability evaluated in situ or in vitro.

Accurate measurements of concentration and ruminal degradability of corn silage starch is necessary for formulation of diets that meet the energy requirements of dairy cows. Five corn silage hybrids ensiled for 0 (unfermented), 30, 60, 120, and 150 d were used to determine the effects of ensiling time on starch degradability of corn silage. In addition, the effects of grind size of silage samples on 7-h in vitro starch degradability and the relationship between in vitro, in situ and near-infrared reflectance spectroscopy (NIRS) starch degradability were studied.

Effects of phytonutrients and yeast culture supplementation on lactational performance and nutrient use efficiency in dairy cows.

Yeast culture and phytonutrients are dietary supplements with distinct modes of action, and they may have additive effects on the performance of dairy cattle. The objective of this study was to investigate the effects of a preparation of phytonutrients and a yeast culture from Saccharomyces cerevisiae on lactational performance, total-tract digestibility of nutrients, urinary nitrogen losses, energy metabolism markers, and blood cells in dairy cows. Thirty-six mid-lactation Holstein cows (10 primiparous and 26 multiparous) were used in an 8-wk randomized complete block design experiment with a 2-wk covariate period, 2 wk for adaptation to the diets, and a 4-wk experimental period for data and samples collection.

Effects of a combination of Capsicum oleoresin and clove essential oil on metabolic status, lactational performance, and enteric methane emissions in dairy cows.

Botanical extracts have a potential to modify ruminal fermentation while enhancing metabolism and immunity in dairy cows. The objective of this study was to investigate the effects of a combination of Capsicum oleoresin and clove essential oil (botanicals; BTC) on lactational performance, nutrient utilization, enteric methane (CH) emissions, and blood parameters in dairy cows. Twenty Holstein cows (12 multiparous and 8 primiparous) averaging (±SD) 77 ± 28 d in milk in the beginning of the study were used in a replicated 4 × 4 Latin square design experiment with 4 periods of 28 d each.

Effects of an exogenous enzyme preparation extracted from a mixed culture of Aspergillus spp. on lactational performance, metabolism, and digestibility in primiparous and multiparous cows.

The objective of this study was to investigate the effects of an exogenous enzyme preparation from Aspergillus oryzae and Aspergillus niger on lactational performance of dairy cows. Forty-eight Holstein cows (32 primiparous and 16 multiparous) averaging (± SD) 36.3 ± 8.

Symposium review: Effective nutritional strategies to mitigate enteric methane in dairy cattle.

Intensive research in the past decade has resulted in a better understanding of factors driving enteric methane (CH) emissions in ruminants. Meta-analyses of large databases, developed through the GLOBAL NETWORK project, have identified successful strategies for mitigation of CH emissions. Methane inhibitors, alternative electron sinks, vegetable oils and oilseeds, and tanniferous forages are among the recommended strategies for mitigating CH emissions from dairy and beef cattle and small ruminants.

Performance of dairy cows fed normal- or reduced-starch diets supplemented with an exogenous enzyme preparation.

The objective of this study was to investigate the effects of supplementation of an exogenous enzyme preparation (EEP) on performance, total-tract digestibility of nutrients, plasma AA profile, and milk fatty acids composition in lactating dairy cows fed a reduced-starch diet compared with a normal-starch diet (i.e., positive control).

Production effects and bioavailability of N-acetyl-l-methionine in lactating dairy cows.

Two experiments were conducted to investigate the production effects of N-acetyl-l-methionine (NALM; experiment 1) and to estimate its bioavailability (BA) and rumen escape (RE; experiment 2), respectively, in lactating dairy cows. In experiment 1, 18 multiparous Holstein cows were used in a replicated, 3 × 3 Latin square design experiment with three 28-d periods. Treatments were (1) basal diet estimated to supply 45 g/d digestible Met (dMet) or 1.

Lactational performance and plasma and muscle amino acid concentrations in dairy cows fed diets supplying 2 levels of digestible histidine and metabolizable protein.

The objective of this experiment was to investigate the effect of dietary levels of digestible histidine (dHis) and MP on lactational performance and plasma and muscle concentrations of free AA in dairy cows. A randomized block design experiment was conducted with 48 Holstein cows, including 20 primiparous, averaging (±SD) 103 ± 22 d in milk and 45 ± 9 kg/d milk yield at the beginning of the experiment. A 2-wk covariate period preceded 12 experimental wk, of which 10 wk were for data and sample collection.

Dietary supplementation with rumen-protected capsicum during the transition period improves the metabolic status of dairy cows.

In ruminants, it has been observed that capsicum oleoresin can alter insulin responses and that high-intensity artificial sweetener can increase glucose absorption from the small intestine. Because glucose metabolism and insulin responses are critical during early lactation, these supplements might have an effect on the metabolic status of dairy cows during the transition period. The objective of this experiment was to evaluate the effects of rumen-protected capsicum oleoresin fed alone or in combination with artificial sweetener during the transition period on lactational performance and susceptibility to subclinical ketosis in dairy cows.