Models to predict the risk of subacute ruminal acidosis in dairy cows based on dietary and cow factors: A meta-analysis

The present research aimed at developing practical and feasible models to optimize feeding adequacy to maintain desired rumen pH conditions and prevent subacute ruminal acidosis (SARA) in dairy cows. We conducted 2 meta-analyses, one using data from recent published literatures (study 1) to investigate the prediction of SARA based on nutrient components and dietary physical and chemical characteristics, and another using internal data of our 5 different published experiments (study 2) to obtain adjustments based on cow status. The results of study 1 revealed that physically effective neutral detergent fiber inclusive of particles >8 mm (peNDF >8) and dietary starch [% of dry matter (DM)] were sufficient for predicting daily mean ruminal pH {y = 5.960 – (0.00781 × starch) + (0.03743 × peNDF >8) – [0.00061 × (peNDF >8 × peNDF >8)]}. The model for time of pH suppression (<5.8 for ruminal pH or <6.0 for reticular pH, min/d) can be predicted with additionally including DMI (kg/d): 124.7 + (1.7007 × DMI) + (20.9270 × starch) + (0.2959 × peNDF >8) – [0.0437 × (DMI × starch × peNDF >8)]. As a rule of thumb, when taken separately, we propose 15 to 18% peNDF >8 as a safe range for diet formulation to prevent SARA, when starch or NFC levels are within 20 to 25% and 35 to 40% ranges, respectively. At dietary starch content below 20% of DM, grain type was insignificant in affecting ruminal pH. However, increasing dietary starch contents by using corn as the sole grain source could lead to more severe drops of pH compared with using grain mix based on barley and wheat, as underlined by an interaction between starch content and grain type. Data from study 2 emphasized an increased risk of SARA for cows in the first and second lactation with lower mean pH (0.2 units) and double amounts of time at pH <5.8 compared with the cows with ≥3 parities. Given that a lower ruminal pH is expected in these high-risk cows, it is advisable to keep the lower end of recommended starch (20%) and higher peNDF >8 (18%) contents in the diet of these cows. Overall, the present study underlines the possibility of predicting SARA based on dietary factors including peNDF >8 and starch contents, as well as DMI of the cows, which can be practically implemented for optimal diet formulation for dairy cows. With more data available, future studies should attempt to improve the predictions by including additional key dietary and cow factors in the models.     

Betaine addition as a potent ruminal fermentation modulator under hyperthermal and hyperosmotic conditions in vitro

The cover image is based on the Research Article Betaine addition as a potent ruminal fermentation modulator under hyperthermal and hyperosmotic conditions in vitro by Mubarik Mahmood et al., https://doi.org/10.1002/jsfa.10255 .

     

Shelf life prediction of packaged cassava-flour-based baked product by using empirical models and activation energy for water vapor permeability of polyolefin films

Moisture sorption kinetics and isotherms of cassava-flour-based baked product were investigated. Empirical models were tested to fit the experimental data. Textural changes of the product were investigated. In addition, activation energies (E_p) for water vapor permeability (WVP) of polyolefin films were determined. Finally, the product was packaged in low-density polyethylene (LDPE) or oriented polypropylene (OPP) pouches, and stored at 30 ± 1 °C and 50 ± 2% RH to simulate actual storage conditions and to determine shelf life. This actual shelf life was compared to the predicted shelf life by using empirical models and E_p for WVP. Moisture sorption kinetics was more rapid during the initial stage, while a lesser amount of moisture was adsorbed as adsorption time increased. The higher the relative humidity used, the more pronounced the effect. The sigmoidal moisture sorption isotherms of this product can be classified as type II. The GAB model was found to be the best-fit model for this product. Once the product hardness or work reached the maximum and began to reduce at moisture content (MC) ≈6%, the product texture began to be detected as becoming slightly soft. This implies that hardness and work at the maximum level could be used to identify the critical MC which causes a loss of crispness to an unacceptable degree. The predicted shelf lives – estimated by employing E_p for WVP of LDPE and OPP, and the GAB model – were close to the actual shelf lives. Therefore, the estimation by empirical models and activation energy was found to be applicable for rapid and accurate shelf life prediction.     

Methods of Emulsifying Linoleic Acid in Biohydrogenation Studies In Vitro May Bias the Resulting Fatty Acid Profiles

The effects of three emulsifying methods on ruminal fatty acid biohydrogenation (BH) in vitro were compared. Using a static in-vitro gas test system, four replicates of each treatment were incubated in buffered ruminal fluid. Hemicellulose (300 mg dry matter) was supplemented either with or without linoleic acid (9c12c-18:2, 5% in diet dry matter) and incubated for 4 and 24 h. Three methods of emulsifying 9c12c-18:2 were tested: (1) ethanol, (2) Tween^® 80, and (3) sonication. The products were then compared to non-emulsified 9c12c-18:2. Out of the three emulsifying methods tested, ethanol and sonication resulted in stable 9c12c-18:2 emulsions, indicating good 9c12c-18:2 distribution, while the Tween^® 80 emulsion was less stable. BH was strongly inhibited by treating 9c12c-18:2 with ethanol and sonication at different steps of the BH-pathway, resulting in changed concentrations of certain BH intermediates. The fatty acid profile generated from the major BH-pathways of 9c12c-18:2 with Tween^® 80 was comparable to that without emulsification after 24 h of incubation. We conclude that it is not recommended to emulsify lipids before incubating them in vitro when investigating fatty acid BH. If emulsification of 9c12c-18:2 is necessary, Tween^® 80 seems to be the method that interferes least with BH.