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Sainte-Anne-de-Bellevue, Canada

Alfonso-Avila A.R.,Laval University | Charbonneau E.,Laval University | Lafreniere C.,University of Quebec | Berthiaume R.,Valacta
Canadian Journal of Animal Science | Year: 2015

This study sought to determine the effect of added glycerol on microbial protein synthesis, ruminal degradation and utilization of alfalfa at different concentrations of nonstructural carbohydrates (NSC), using in vitro gas production. The 2×3 factorial plus one treatment consisted of oven-dried alfalfa with two NSC levels [high: 17.9 (HNSC) or low: 7.4% dry matter (DM) (LNSC)] and three glycerol treatments [control without glycerol, 15% crude glycerol (CG) and 15% pure glycerol (PG)], the additional treatment was LNSC+exogenous sugars (LNSC+ES: LNSC with 5% sucrose+5% starch). Five pre-planned contrasts were evaluated from the seven treatments: (1) HNSC vs. LNSC alfalfa; (2) with glycerol vs. without; (3) interaction of alfalfa and glycerol; (4) CG vs. PG, and; (5) LNSC+ES vs. HNSC. Gas production over 24 h was higher for HNSC than LNSC (202 vs. 179 mL g−1 DM) and with glycerol than without glycerol (202.2 vs. 168 mL g−1 DM). A decrease in the acetate:propionate ratio was observed for HNSC compared with LNSC (2.87 vs. 3.27) and for the addition of glycerol vs. no glycerol (2.78 vs. 3.65). Reduced microbial mass (185.5 vs. 240.5 mg g−1 DM) was observed for CG compared with PG. The LNSC+ES treatment had lower microbial protein synthesis and propionic acid production in relation to HNSC. No significant interaction was observed between the effect of NSC content of alfalfa and glycerol utilization. When effects were studied separately, results indicate that increasing NSC in alfalfa stimulates the synthesis of microbial protein. Also, the addition of glycerol promotes the synthesis of glucose precursors. Finally, the type of glycerol has an impact on results obtained suggesting caution when extrapolating results for PG to CG. © 2015, Agricultural Institute of Canada. All Rights Reserved. Source

Denis-Robichaud J.,University of Montreal | Dubuc J.,University of Montreal | Lefebvre D.,Valacta | DesCOteaux L.,University of Montreal
Journal of Dairy Science | Year: 2014

The objectives of this study were (1) to determine the correlations between blood β-hydroxybutyrate (BHBA) and milk components [BHBA, acetone, fat, protein, and fat:protein (F:P) ratio], and (2) to establish optimal thresholds for milk components to predict hyperketonemia in dairy cows. Data on 163 cows from 37 herds were used in this cross-sectional study. Herds were visited once during the study period, and cows between 2 and 90 d in milk were blood sampled within 4. h of milk sampling for the Dairy Herd Improvement test. Blood BHBA concentrations were measured using a cow-side electronic meter, Precision Xtra, which was considered the gold standard test in this study. Milk BHBA and acetone concentrations were measured in Dairy Herd Improvement milk samples by flow-injection analysis; whereas, milk fat and protein were tested using Fourier transform infrared spectroscopy. Hyperketonemia was defined by a blood BHBA concentration ≥1.4. mmol/L. The prevalence of hyperketonemia (based on blood BHBA values) in this study population was 21.0%. Pearson correlation coefficients between blood BHBA and milk BHBA, acetone, fat, protein, and F:P ratio were 0.89, 0.73, 0.21, 0.04, and 0.17, respectively. Receiver operating characteristic curves were generated and thresholds for each individual milk component were determined based on the maximal sum of sensitivity and specificity. Optimal threshold values for hyperketonemia were milk BHBA ≥0.20. mmol/L, acetone ≥0.08. mmol/L, fat ≥4.2%, and F:P ratio ≥1.3. Based on these thresholds, milk BHBA and acetone had greater sensitivity (84 and 87%, respectively) and greater specificity (96 and 95%, respectively) than the other milk components (fat, protein, and F:P). Series and parallel testing slightly improved the accuracy of milk BHBA and acetone values to predict hyperketonemia. A multivariable model that accounted for milk BHBA and milk acetone values simultaneously had the highest accuracy of all tested models for predicting hyperketonemia. These results support that milk BHBA and milk acetone values from flow-injection analysis are accurate diagnostic tools for hyperketonemia in dairy cows and could potentially be used for herd-level hyperketonemia surveillance programs. © 2014 American Dairy Science Association. Source

Gibbons J.,Agriculture and Agri Food Canada | Haley D.B.,University of Guelph | Higginson Cutler J.,University of Guelph | Nash C.,University of Guelph | And 7 more authors.
Journal of Dairy Science | Year: 2014

We compared 2 methods for identifying lame cows and estimating the prevalence of lameness in tiestalls. Cows (n. = 320) in 9 tiestall herds were scored as lame both by the presence of limping while walking and by stall lameness scores (SLS). The SLS was based on the number of the following behaviors that the cow showed while standing in the tiestall: weight shifting, standing on the edge of the stall, uneven weight bearing while standing, and uneven weight bearing while moving from side to side. Two observers watched video-recordings of the cows. Intraobserver agreements for the 4 SLS behaviors ranged from 92 to 100%, and interobserver agreement ranged from 81 to 100%. The overall prevalence of lameness based on an SLS of ≥2 was similar to that of limping (39 vs. 40%). The sensitivity of the classification based on the SLS was 0.63 and the specificity was 0.77 in identifying cows with a limp; accuracy varied across farms from 62.2 to 80.4%, with a mean of 71.7%. A cow with an SLS of ≥2 had 4.88 times the odds of limping than a cow with an SLS of <2. The prevalence of lameness on farms based on SLS was highly correlated with the prevalence of limping (Pearson correlation. = 0.88; n. = 9), and prevalence estimates from the 2 methods diverged most when the mean herd prevalence was lower. The SLS method provides an estimate of the prevalence of lameness in tiestall herds comparable with traditional gait scoring, but does not require that the cows be untied. The SLS method could be used to improve lameness detection on tiestall farms and obtain estimates of lameness prevalence without the need to walk the cows. © 2014 American Dairy Science Association. Source

Santschi D.E.,Agriculture and Agri Food Canada | Santschi D.E.,Laval University | Lefebvre D.M.,Valacta | Cue R.I.,McGill University | And 2 more authors.
Journal of Dairy Science | Year: 2011

The Canadian dairy industry operates under a supply management system with production quotas (expressed in kilograms of butterfat per day) owned by dairy producers. Any management strategy influencing production responses must, therefore, be evaluated to estimate its effects on quota needed to sell the milk produced. In the present study, half of the cows from 13 commercial herds (850 cows, average of 70 cows per herd) were assigned to be managed for a short dry period (SDP; 35 d dry) and the other half was managed for a conventional dry period (CDP; 60 d dry) to evaluate the economic impact of a steady state involving either CDP or SDP. Economic variables included in the partial budget were: variations in revenues from milk and components as well as animals sold; costs related to feeding, reproduction, replacement, housing, and treatments. All variables were first estimated on a cow basis for each herd individually, and average results were used to calculate the partial budget for an average herd. Yearly milk and component yields per cow increased, which implies that fewer cows are required to produce the same amount of quota. Accordingly, 2 scenarios were investigated: in the first one, available quota was kept constant, and herd size was adjusted to avoid over-quota production. Consequently, the partial budget was calculated considering that 5 fewer cows were present in the herd. In this situation, switching to an SDP management increased net annual income for the farm by $2,677 (Can$), which represents $41.38 per cow. In the second scenario, the number of cows was kept constant, but additional quota (5.5 kg/d, $25,000/kg) was bought to allow selling all of the milk produced. In this case, net farm income was increased by $17,132 annually with SDP, which represents $245.18 per cow. This budget includes interest on the purchase of quota. A comparison of partial budgets for individual herds involved in the study revealed considerable variation among herds. Switching from a CDP to a SDP management would be beneficial for average dairy herds in eastern Canada. © 2011 American Dairy Science Association. Source

Santschi D.E.,Laval University | Santschi D.E.,Agriculture and Agri Food Canada | Lefebvre D.M.,Valacta | Cue R.I.,McGill University | And 2 more authors.
Journal of Dairy Science | Year: 2011

A total of 850 cows distributed among 13 commercial Holstein herds were involved in this study to compare the effects of 2 different dry period (DP) management strategies on milk and component yields as well as body condition score (BCS) over complete lactations. Within each herd and every 2 mo, cows were assigned to a short (35 d dry; SDP) or conventional (60 d dry; CDP) DP management based on previous lactation 305-d milk yield, predicted calving interval, and parity: primiparous (n. =414) and multiparous (n. =436). Cows assigned to CDP were fed a far-off dry cow ration from dry-off until 21 d prepartum, and were then switched to a precalving ration. Cows assigned to SDP were fed the precalving ration throughout their DP. Rations were different across herds, but the late-lactation, precalving, and early lactation rations were identical for both treatment groups within each herd. Additional milk was obtained at the end of lactation from cows assigned to SDP due to the extended lactation. Average daily milk yield in the following lactation was not different between treatments for third- or greater-lactation cows, but was significantly decreased in second-lactation SDP cows. However, when expressed as energy-corrected milk, this difference was not significant. Although lower for primiparous than multiparous cows, body weight and BCS were not affected by DP management strategy. Milk production and BCS responses to treatments varied among herds. Results from the present study suggest that a short DP management strategy could be more appropriate for today's dairy cows, although not suitable for all cows or all herds. © 2011 American Dairy Science Association. Source

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