Feeding a marine-based rumen buffer increases milk production and decreases time of low reticulo-rumen pH in grazing dairy cows offered perennial ryegrass-based pasture

Potential use of seaweed as a dietary supplement to mitigate enteric methane emission in ruminants

Seaweeds or marine algae exhibit diverse morphologies, sizes, colors, and chemical compositions, encompassing various species, including red, green, and brown seaweeds. Several seaweeds have received increased research attention and application in animal feeding investigations, particularly in ruminant livestock, due to their higher yield and convenient harvestability at present. Recent endeavors encompassing both in vitro and in vivo experiments have indicated that many seaweeds, particularly red seaweed (Asparagopsis taxiformis and Asparagopsis armata), contain plant secondary compounds, such as halogenated compounds and phlorotannins, with the potential to reduce enteric ruminal methane (CH4) emissions by up to 99 % when integrated into ruminant diets. This review provides an encompassing exploration of the existing body of knowledge concerning seaweeds and their impact on rumen fermentation, the toxicity of ruminal microbes, the health of animals, animal performance, and enteric ruminal CH4 emissions in both in vitro and in vivo settings among ruminants. By attaining a deeper comprehension of the implications of seaweed supplementation on rumen fermentation, animal productivity, and ruminal CH4 emissions, we could lay the groundwork for devising innovative strategies. These strategies aim to simultaneously achieve environmental benefits, reduce greenhouse gas emissions, enhance animal efficiency, and develop aquaculture and seaweed production systems, ensuring a high-quality and consistent supply chain. Nevertheless, future research is essential to elucidate the extent of the effect and gain insight into the mode of action.

The effects of antibiotic-free supplementation on the ruminal pH variability and methane emissions of beef cattle under the challenge of subacute ruminal acidosis (SARA)

Subacute ruminal acidosis (SARA) in feedlot cattle during the feed transition to grain-based diets is a significant constraint to animal health and productivity. This experiment assessed an antibiotic-free supplement (ProTect®) effects on ruminal pH variability and methane (CH₄) emissions of cattle during the challenge of SARA. Ten 18-month-old Angus steers (472 ± 4.8 kg) were randomly allocated into monensin (n = 5) and ProTect® groups (n = 5) and progressively introduced to grain diets incorporating monensin or ProTect® for 36 days of the experiment [starter (7 days; 45% grain), T1 (7 days; 56% grain), T2 (7 days; 67% grain), finisher (15 days; 78% grain)]. The pH variability on the finisher period was reduced by the ProTect® supplement (6.6% vs. 5.2%; P < 0.01), with CH₄ emissions being significantly higher relative to the monensin group [88.2 g/day (9.3 g CH₄/kg DMI) vs. 133.7 g/day (14.1 g CH₄/kg DMI); P < 0.01]. There was no difference between treatments in the time spent on the ruminal pH < 5.6 or < 5.8 (P > 0.05). The model evaluation for the ruminal pH variation indicated that the mean absolute error (MAE) proportion for both groups was good within the same range [4.05% (monensin) vs. 4.25% (ProTect®)] with identical root mean square prediction error (RMSPE) (0.34). It is concluded that the ProTect® supplement is an effective alternative to monensin for preventing SARA in feedlot cattle by managing ruminal pH variation during the transition to high-grain diets. Both monensin and ProTect® supplemented cattle exhibited lower CH₄ yield compared to cattle fed forages and low-concentrate diets.

Comparison of milk and grass composition from grazing Irish dairy herds with and without milk fat depression

BACKGROUND

This study investigated the factors relating to pasture chemical and fatty acid (FA) composition that influence the milk fat percentage of spring calving, grazing dairy cows. The relationship between milk fat percentage and FA composition of the milk in these herds was also investigated.

RESULTS

Milk protein percentage, milk casein percentage and cheddar cheese yield were increased in milk from HMF herds. Cows from LMF herds did not have negatively altered milk processability including rennet coagulation time (RCT), pH and ethanol stability. Crude protein, NDF, ADF, ether extract and total FA content of pasture was not different between LMF and HMF herds. Milk fat concentration of conjugated linoleic acid (CLA) t10, c12 was not different between HMF and LMF herds. Pre-grazing herbage mass and pasture content of crude protein, neutral detergent fibre (NDF) and total FA were similar between HMF and LMF herds. Pasture offered to LMF herds had a higher concentration of monounsaturated fatty acids (MUFA). A strong negative relationship (r = -0.40) was evident between milk fat percentage and pasture crude protein content for MMF herds (3.31-3.94% milk fat).

CONCLUSIONS

This research reports improved milk protein percentage, milk casein percentage and cheddar cheese yield from HMF herds compared to LMF herds. Milk processability was not impacted by low milk fat percentage. Pasture NDF and total fatty acid content was similar in HMF herds and LMF herds. Milk fat percentage had a strong negative association (r = -0.40) with pasture crude protein content in MMF herds (MF 3.31-3.94%). Correlation values between pasture chemical and FA composition and milk fat percentage in LMF herds and HMF herds were low, indicating that diet is not the only causative factor for variation in milk fat of grazing dairy cows. Comparison of milk fatty acid composition from herds with and without milk fat depression suggests that there may be other fatty acids apart from CLA t10, c12 that contribute to the inhibition of milk fat synthesis during milk fat depression in grazing herds.

Invited review: Effect of subacute ruminal acidosis on gut health of dairy cows

Subacute ruminal acidosis (SARA) is assumed to be a common disease in high-yielding dairy cows. Despite this, the epidemiological evidence is limited by the lack of survey data. The prevalence of SARA has mainly been determined by measuring the pH of ruminal fluid collected using rumenocentesis. This may not be sufficiently accurate, because the symptoms of SARA are not solely due to ruminal pH depression, and ruminal pH varies among sites in the rumen, throughout a 24-h period, and among days. The impact of SARA has mainly been studied by conducting SARA challenges in cows, sheep, and goats based on a combination of feed restriction and high-grain feeding. The methodologies of these challenges vary considerably among studies. Variations include differences in the duration and amount of grain feeding, type of grain, amount and duration of feed restriction, number of experimental cows, and sensitivity of cows to SARA challenges. Grain-based SARA challenges affect gut health. These effects include depressing the pH in, and increasing the toxin content of, digesta. They also include altering the taxonomic composition of microbiota, reducing the functionality of the epithelia throughout the gastrointestinal tract (GIT), and a moderate inflammatory response. The effects on the epithelia include a reduction in its barrier function. Effects on microbiota include reductions in their richness and diversity, which may reduce their functionality and reflect dysbiosis. Changes in the taxonomic composition of gut microbiota throughout the GIT are evident at the phylum level, but less evident and more variable at the genus level. Effects at the phylum level include an increase in the Firmicutes to Bacteroidetes ratio. More studies on the effects of a SARA challenge on the functionality of gut microbiota are needed. The inflammatory response resulting from grain-based SARA challenges is innate and moderate and mainly consists of an acute phase response. This response is likely a combination of systemic inflammation and inflammation of the epithelia of the GIT. The systemic inflammation is assumed to be caused by translocation of immunogenic compounds, including bacterial endotoxins and bioamines, through the epithelia into the interior circulation. This translocation is increased by the increase in concentrations of toxins in digesta and a reduction of the barrier function of epithelia. Severe SARA can cause rumenitis, but moderate SARA may activate an immune response in the epithelia of the GIT. Cows grazing highly fermentable pastures with high sugar contents can also have a low ruminal pH indicative of SARA. This is not accompanied by an inflammatory response but may affect milk production and gut microbiota. Grain-based SARA affects several aspects of gut health, but SARA resulting from grazing high-digestible pastures and insufficient coarse fiber less so. We need to determine which method for inducing SARA is the most representative of on-farm conditions.

Novel Crabtree negative yeast from rumen fluids can improve rumen fermentation and milk quality

Upgrading the nutritive value of rice straw (RS) is necessary to increase its contribution to enhancing meat and milk production. Present work verified whether novel Crabtree negative yeast inoculant could promote RS utilization, rumen fermentation, and milk quality in tropical crossbred lactating Holstein cows. The new stain of Crabtree negative yeasts (Pichia kudriavzevii KKU20 and Candida tropicalis KKU20) was isolated from the rumen of dairy cattle. This study used 6 multiparous crossbreds between Holstein Frisian × Zebu dairy cows in their mid-lactation period. Dairy cows were randomly allocated to three ensiled RS with various yeast stains including Saccharomyces cerevisiae, P. kudriavzevii KKU20, and C. tropicalis KKU20 according to a 3 × 3 replicated Latin square design. Crabtree-negative yeast (P. kudriavzevii and C. tropicalis) increased the apparent digestibility of dry matter by about 6.9% when compared with Crabtree-positive yeast (S. cerevisiae). Bacterial populations were highest with ensiled RS by C. tropicalis KKU20. Ensiled RS with Crabtree-negative yeasts were significantly increased with total volatile fatty acids, but they did not affect volatile fatty acid profiles. Milk protein precentage was highest at 35.6 g/kg when C. tropicalis was fed, and lowest when applied with S. cerevisiae and P. kudriavzevii KKU20 in ensiled RS at 34.5 and 34.1 g/kg, respectively. Thus, feeding ensiled RS with novel Crabtree negative yeast could improve RS digestion, rumen fermentation, and milk protein content in dairy cows.