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Varying the time since the last meal (i.e. fasting) is a means of manipulating foraging behaviour. Management practices that restrict grazing time, and/or change the timing of the grazing session, may be analogous to changes introduced with different fasting regimes, suggesting that the same pattern of responses on foraging behaviour could be expected. Concepts related to eating patterns of grazing dairy cows are briefly reviewed, and impacts of short-term (i.e. within day) fasts on ingestive behaviours are discussed. Finally, several experiments that examined impacts of short-term fasts on eating patterns, ingestive behaviours and performance of lactating dairy cows are reviewed. Management practices that create shorter grazing sessions (i.e. longer fasting periods before grazing), and/or involve afternoon grazing, result in longer initial grazing bouts, higher intake rates, reductions in rumination time during the grazing session, as well as more pronounced changes in rumen pH, concentrations of rumen fermentation metabolites and rumen load. All of these changes have been associated with improvements in performance of grazing dairy cattle. These concepts and findings have implications in defining optimal grazing strategies, as well as allowing cattle performance, sward conditions and nutrient balances to be predicted and analysed in an integrated manner.

Psychrotrophic yeasts were isolated from Antarctic soils, selected based on their ability to grow in apple juice at low temperatures, and were evaluated as potential biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, an isolate of Leucosporidium scottii, designated At17, was identified as a good biocontrol agent for blue and gray mold of two apple cultivars. The selected isolate produced soluble and volatile antifungal substances that were inhibitory to apple pathogens. Siderophore production was also demonstrated, but it did not appear to play a role in pathogen inhibition. The selected yeast had the capacity to form a biofilm when grown in apple juice, which is considered an important attribute of postharvest antagonists to successfully colonize wounds and intact fruit surfaces. At17 was resistant to commonly used postharvest fungicides, so application of a combination of low-dose fungicide along with the biocontrol agent could be used as an integrated management practice.

The objective of this study was to investigate the effect of different body condition score (BCS) at 30 days before calving (230 days) induced by a differential nutritional management from 2100 days until 230 days on productive parameters, the interval to first ovulation and blood parameters in primiparous and multiparous Holstein cows under grazing conditions until 60 days post partum. The experimental arrangement was a randomized complete block design, where cows were blocked according to BW and expected calving date and then randomly assigned to different nutritional treatments from -100 to -30 days relative to calving to induce different BCS. As the assignment of cows to treatments was random, cows had to lose, maintain or gain BCS; thus, different planes of nutrition were offered with approximately 7, 14 or 20 kg dry matter per day. The BCS score was assessed every 15 days and animals were reassigned in order to achieve the desired BCS at -30 days. Only animals that responded to nutritional treatment were considered and this was defined as follows: primiparous and multiparous high cows (PH and MH) had to gain 0.5 points of BCS, primiparous low (PL) had to lose 0.5 points of BCS and multiparous low (ML) had to maintain BCS at least in two subsequent observations from 2100 to 230 days. From 230 days to calving, primiparous and multiparous cows (P and M cows) were managed separately and cows were offered a diet once a day. From calving to 60 days post partum, cows of different groups grazed in separate plots a second year pasture. Cows were also supplemented individually with whole-plant maize silage and commercial concentrate. Cows had similar BCS at 2100 days and differed after the nutritional treatment; however, all groups presented similar BCS at 21 days post partum. The daily milk production and milk yield at 60 days post partum was higher in M than P cows. The percentage of milk fat was higher in PH cows compared with PL cows. Concentrations of non-esterified fatty acids (NEFA) were affected by the BCS at 230 days within parity, and in PH cows the concentration of NEFA was higher than in PL cows. The concentrations of total protein were higher in M cows. A lower probability of cycling was found in PL than in PH cows (P , 0.05) and in ML than in MH cows (P , 0.05). Treatment affected various endocrine/metabolic profiles according to parity, suggesting that the metabolic reserves signal the productive/reproductive axis so as to induce a differential nutrient partitioning in adult v. first-calving cows.

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