The Research Column

Extending the voluntary waiting period (VWP) from calving until first insemination is one way of extending the lactation length beyond 305 days, which will result in an extended lactation length and CI. With an extended CI, the risk of diseases per year can be expected to reduce as there will be fewer calving events per year. It has been shown that cows with an extended VWP (150 days) had a lower incidence of metabolic disorders, lower veterinary costs and lower culling rates compared with cows with a short VWP (60 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 applied in these studies varied considerably. Variations include differences in the duration and amount of grain feeding, the type of grain, the amount and duration of the feed restriction, the number of experimental cows, and the sensitivity of the cows themselves to the SARA challenges.

Studies evaluating RFI divergence between dairy cows have usually been performed during established lactation. Whether shortening the feeding period and increasing the number of cows would enhance the ability to detect physiological differences between the most efficient and  least efficient cows is largely unknown.

Cheese production is from fermentation processes by starter cultures used to generate lactic acid enabling gel syneresis, whey expulsion, and curd formation. Natural whey cultures (NWC) are undefined cheese starters obtained by the traditional back-slopping procedure. They play a key role in cheese specificity, uniqueness, and development of sensory characteristics.

Methane emissions and rumen fermentation characteristics of the dairy cows fed 100% plantain (PLT) or 100% perennial ryegrass (RG; Lolium perenne) were measured in two experiments (E1 and E2). The forages were in a vegetative growth stage in E1 and were in a reproductive growth stage in E2. The CH4 emissions from 16 cows in each experiment were measured in respiration chambers for two days.

Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 days before their expected calving date. Both groups received the same diet, except for the source of trace minerals (TM). The STM group was supplemented with Co, Cu, Mn and Zn sulfates and Na selenite, whereas the OTM group was supplemented with Co, Cu, Mn and Zn proteinates and selenized yeast.

The study used 2616 calves entering a calf-rearing facility for veal calves in Canada. The results nevertheless are considered relevant to rearing of heifer calves on farm. Faecal consistency scores were assigned twice daily for the first 28 days following arrival, where a score of 2, indicating runny consistency, and 3, indicating watery consistency, were classified as diarrhoea. Severe diarrhoea was classified by a score of 3. Serum total protein was measured upon arrival and the source of the calf (i.e., whether the calf came from a calf seller, local farm, or auction) was recorded.

Discipline: calf rearing; Keywords: individual housing, starter intake, group housing, automatic feeding system, target weight, respiratory problems.

The question addressed is when pre-weaning calves housed individually can be grouped successfully without increasing stress and the incidence of disease. This research by Drs Bach in colleagues was published in The Journal of Dairy Science, Volume 93 of 2010, pages 413 to 419. The title of the paper is: Optimizing weaning strategies of dairy replacement calves.

Discipline: carbon footprint; Keywords: climate change, rumen fermentation, manure, beef cattle, dairy cattle, smallstock, pigs, poultry, game.

Discipline: technology adoption; Keywords: structural changes, labour, efficient operations, holding pen, udder washer, breeding technologies, coputerized milking systems.