A survey of Canadian dairy nutritionists to assess current trace element formulation practices.

The purpose of this study was to identify current practices and perceptions around trace element feeding for dairy cows through a Canadian dairy nutritionist survey. An online survey with 23 questions was used to collect data from Canadian dairy nutritionists with the help of professional associations and social media. The survey was active from November 2021 to April 2022. The first 7 questions collected descriptive information on respondents, and the subsequent 16 questions focused on trace element feeding. A total of 92 participants from all over Canada filled out the survey, and about 26% of Canadian herds and cows were represented by these respondents. The participants had diverse views on the importance of diet formulations for trace elements to optimize cow health and productivity, with perceptions varying from very important to not important. In comparison, macronutrients and selenium were consistently rated as very important by between 58% and 74% of respondents. Software reference values were used by 54%, 72%, and 73% of participants to estimate trace element concentrations of forages, cereals, and protein sources, respectively, highlighting the importance of regularly updating the feed library of the software. More than 60% of nutritionists participating in this study had intentionally formulated diets above trace element software recommendations, considered mineral interactions occurring in the rumen, and used a trace element source known for its better bioavailability (e.g., organic, chelate) when they formulated diets. Herds with more than 80 cows were more likely to be given trace element supplements known for their greater bioavailability. The most used supplement with enhanced bioavailability was selenium. In addition, different trace element feeding strategies pertaining to different stages of lactation and breeds were reported. This finding can be explained by the absence of clear recommendations on trace element feeding by breed. The participants who adjusted trace element feeding according to the stages of lactation considered the transition period as the most challenging period, and they identified the need for a source of trace element known for its greater bioavailability for this period. Further research should aim to identify environmental risk of trace element overfeeding using the One Health approach. Moreover, strategies to avoid trace element overfeeding should be evaluated.

Preferences of Dairy Cattle for Supplemental Light-Emitting Diode Lighting in the Resting Area.

Light from the environment is important for vision and regulating various biological processes. Providing supplemental lighting in the stall area could allow for individually targeted or group-level control of light. This study aimed to determine whether dairy cattle had preferences for short-term exposure to white (full-spectrum) light-emitting diode (LED) light or no LED light, yellow-green or white LED light, and blue or white LED light in the stall area. In total, 14 lactating cows were housed in a free-stall pen with unrestricted access to 28 stalls. LED light was controlled separately for each side of the stall platform. Two combinations of light were tested per week, and each week consisted of three adaptation days and four treatment days. Lying behaviour and video data were recorded continuously using leg-mounted pedometers and cameras, respectively. Preference was assessed by the amount of time spent lying and the number of bouts under each light treatment. No differences occurred between treatments within each week for daily lying time and number of bouts. Similarly, no differences occurred between treatments within each time period. Further controlled studies of long-term exposure to different LED wavelengths and intensities are required to determine potential benefits on metabolic processes.

Application of iTRAQ to catalogue the skeletal muscle proteome in pigs and assessment of effects of gender and diet dephytinization.

In this study iTRAQ was used to produce a highly confident catalogue of 542 proteins identified in porcine muscle (false positive<5%). To our knowledge this is the largest reported set of skeletal muscle proteins in livestock. Comparison with human muscle proteome demonstrated a low level of false positives with 83% of the proteins common to both proteomes. In addition, for the first time we assess variations in the muscle proteome caused by sexually dimorphic gene expression and diet dephytinization. Preliminary analysis identified 19 skeletal muscle proteins differentially expressed between male and female pigs (> or = 1.2-fold, p<0.05), but only one of them, GDP-dissociation inhibitor 1, was significant (p<0.05) after false discovery rate correction. Diet dephytinization affected expression of 20 proteins (p<0.05). This study would contribute to an evaluation of the suitability of the pig as a model to study human gender-related differences in gene expression. Transgenic pigs used in this study might also serve as a useful model to understand changes in human physiology resulting from diet dephytinization.

Microbial fatty acid conversion within the rumen and the subsequent utilization of these fatty acids to improve the healthfulness of ruminant food products.

Consumers are aware of foods containing microcomponents that may have positive effects on health maintenance and disease prevention. In ruminant milk, meat, and milk products; these functional food components include eicosapentaenoic acid (20:5n3), docosahexaenoic acid (22:6n3), 9c11t-conjugated linoleic acid, and vaccenic acid (11t-18:1). Modifying ruminal microbial metabolism of fatty acid in rumen through animal diet formulation is an effective way to enhance these functional fatty acids in ruminant-derived food products. However, it requires an understanding of the interrelationship between supply of lipid through the diet and rumen fermentation. Lipids in ruminant diets undergo extensive hydrolysis and biohydrogenation in the rumen. Apparent transfer efficiency of eicosapentaenoic acid and docosahexaenoic acid from feed to milk is very low (1.9 to 3.3%), which is, to a large extent, related to their extensive biohydrogenation in the rumen. Therefore, feeding a rumen-protected supplement containing eicosapentaenoic acid and docosahexaenoic acid, can be used to bypass the rumen. Ruminant-derived foods also contain different types of conjugated linoleic acid isomers, which are intermediates of rumen biohydrogenation of linoleic acid (9c12c-18:2). The predominant isomer of conjugated linoleic acid is 9c11t, which has numerous health benefits in animal models. The concentration of conjugated linoleic acid in ruminant-derived food products can be significantly enhanced through animal diet modification. We conclude that most current functional food products from ruminants have potential for their health-supporting properties, and for this market to succeed, an evidence-based approach should be developed in humans.

Fatty acid profile of bovine milk naturally enhanced with docosahexaenoic acid.

Recent studies have shown that the fatty acid profile of dietary lipid has the potential for improving the health of consumers. The present study was conducted to determine the fatty acid composition of commercial milks, namely, Dairy-Oh! Homo-Milk (DOHM), which is naturally enhanced with docosahexaenoic acid (DHA), or regular Homo-Milk (HM). The milk was collected from local supermarkets. The most abundant saturated fatty acids in the milk were butyric (C4:0), lauric (C12:0), myristic (C14:0), palmitic (C16:0), and stearic (C18:0) acids. Among unsaturated fatty acids, oleic acid (cis-9-C18:1) was also considerably high (502.7 mg/100 mL of milk). The concentration of total trans-18:1 was higher (P < 0.05) in DOHM than in HM (134.7 vs 107.0 mg/100 mL of milk, respectively), whereas total cis-18:1 was higher (P < 0.05) in HM than in DOHM (566.4 vs 508.4 mg/100 mL of milk, respectively). The concentration of DHA was 24.0 times higher (P < 0.05) in DOHM than in HM. DOHM contained 2.8 times higher (P < 0.05) eicosapentaenoic acid (EPA) compared to HM. Milk fat from DOHM contained a greater concentration of cis-9,trans-11 conjugated linoleic acid (CLA, 16.4 vs 11.6 mg/100 mL of milk, DOHM vs HM, respectively). The total omega-3 polyunsaturated fatty acids content was 2.23 times greater (P < 0.05) in DOHM compared with HM, due to an increase in C18:3n-3, EPA, and DHA. The result of the milk fatty acid analyses indicates that milk fat from DOHM had increased contents of EPA, DHA, and cis-9,trans-11 CLA, which could have a more favorable impact on diet composition and healthfulness.