J.A. Shelford

Effect of adding lignosulfonate and heat to canola screenings on ruminal and intestinal disappearance of dry matter and crude protein.

The effect of adding 5% calcium lignosulfonate (LSO3) and heat to canola screenings on in situ ruminal and intestinal dry matter (DM) and crude protein (CP) disappearance in Holstein cows was investigated. Treatments consisted of untreated canola screenings, canola screenings that had been heated to 100 °C for 30 or 60 min and canola screenings that had 5% (wt wt−1) LSO3 added and were subsequently heated at 100 °C for 0, 30 or 60 min. Results indicate that treatment of canola screenings with 5% LSO3 and heated to 100 °C for 60 min was effective in reducing rumen degradation of DM and CP with a corresponding increase in disappearance in the lower gastrointestinal tract when compared to untreated and heat-treated canola screenings. Key words: Canola screenings, rumen by-pass protein, heat treatment, lignosulfonate

The effect of concentration and form of dietary nitrogen on the utilization and excretion of nitrogen by lactating dairy cows.

Three total mixed rations containing differing sources and levels of protein were fed to 18 lactating cows in a 3 × 3 Latin square design with the objective of quantitating nitrogen losses for specific feeding regimes. Feeding a total mixed ration containing 12.3% crude protein reduced the amount of nitrogen excreted and increased the proportion of dietary nitrogen secreted in the milk. The diet supplemented with corn gluten meal resulted in high blood urea nitrogen levels and higher losses of nitrogen in the urine. It was concluded that diet formulation impacts on nitrogen wastage. Key words: Lactating cows, nitrogen source, level and wastage

In vitro degradation of fresh substrates treated with exogenous fibrolytic enzymes

An exogenous fibrolytic enzyme product was applied to three different proportions of a total mixed ration (TMR) and fed to dairy cows. There was no enhancement of the hydrolytic capacity of rumen fluid from cows serving as inoculum donors as a result of enzyme supplementation. In vitro dry matter degradation of the TMR at 12 h of incubation was increased by 15% when enzymes were added to the concentrate portion, and by 17% when added to the premix portion of the TMR (P < 0.05), but adding enzymes to the supplement (pelleted portion of the concentrate) had no effect. Key words: Enzymes, fresh substrate, dry matter degradation

Effect of feeding textured concentrates with alfalfa cubes to lactating dairy cows producing low fat milk

Twenty–one multiparous Holsteins were used in a cross over design with two 28-d periods. Cows were randomly assigned to two treatments to assess the effect of textured and pelleted concentrates fed with alfalfa cubes on feed intake, milk yield, milk composition and rumen volatile fatty acid concentrations. Those animals receiving the textured concentrate had significantly (P < 0.05) higher milk yield and milk fat percentage than did those animals fed the pelleted concentrate. A significant difference in the ratio of milk protein to milk fat was also observed with the cows receiving the pelleted concentrate having a ratio of 1.31 and the cows receiving the textured concentrate a ratio of 1.02. No significant (P < 0.05) differences were observed between the textured and pelleted feeds in total or individual volatile fatty acid concentrations. These results indicate that the feeding of textured concentrates can lead to an increase in milk fat production when compared with the feeding of pelleted concentrates...

Use of the Cornell Net Carbohydrate and Protein System and rumen-protected methionine to maintain milk production in cows receiving reduced protein diets

Twenty-two primiparous and forty-eight multiparous lactating Holstein cows were used in a production trial. Cowswere randomly assigned to two treatments to assess the effects of formulating a lower crude protein (CP) diet using the Cornell Net Carbohydrate and Protein Model (CNCPS), which included rumen-protected methionine and a bypass protein on group feed intake, milk yield, milk composition and blood urea nitrogen (BUN) status. Those animals receiving the lower CP diet were able to maintain milk production (P > 0.05) and milk component yield (P > 0.05) when compared with the animals receiving the control diet. Although no statistical analysis could be undertaken on the dry matter intake data, due to insufficient degrees of freedom, group intakes appeared to be similar. Multiparous cows were also observed with the cows receiving the diet supplemented with bypass methionine and bypass protein had significantly lower BUN levels when compared with the control cows. These results indicate that the CNCPS mo...

A comparison of textured versus pelleted concentrates on rumen degradability, dry matter intake, milk yield and composition in lactating Holstein cows

A study was undertaken to compare the feeding of a ground-pelleted concentrate mixture with a textured one. Parameters studied were in situ rumen degradability characteristics of the concentrates, dry matter intake and yield of milk and milk components. A concentrate mixture consisting of barley, corn, canola meal and a vitamin-mineral premix was manufactured in two forms. In the one form, all ingredients were ground and pelleted while in the second, only the canola meal and premix were pelleted while the corn and barley were steam rolled prior to mixing. Initially the degradability characteristics and digestive tract disappearance of the two concentrates were determined in an in situ trial using two non-lactating Holstein cows fitted with rumen and duodenal cannulae. Nylon bags containing 2–3 g of material were prepared in quadruplicate (two replicates per cow per incubation time) and incubated in reverse order 72, 48, 24, 12, 8, 4, 2 and 0 h for each concentrate. Total intestinal disappearance was deter...