Increasing intake by the development of optimal grazing management in relation to animal behaviour at pasture.

End of Project ReportIn each month from July to December, grazing activity for each of 12 animals was recorded over a number of days continuously using vibrarecorders. The work was done at Killarney National Park and the animals were heifers of the Kerry breed living under semi-natural conditions with abundant pasture available. In July (16 hour day-length) - all animals began grazing at dawn and grazed for about 2.5 hours. This first bout was followed at intervals of about 2 hours by shorter bouts each about one hour in duration. In late afternoon another bout commenced which continued for 4 to 5 hours through until after dusk. During darkness, about midnight, there was a short bout of grazing. All of the animals behaved thus and the pattern was repeated each day. Total grazing time was near 11 hours each day. By October day-length had decreased. There was still a bout at dawn and a bout at sunset. As in July there were three smaller bouts but all occurred during darkness. The total grazing time was close to 11 hours as before. The pattern of grazing was consistent between animals and days. In August-September-October and November there were always two major bouts of grazing related to dawn and dusk. Grazing total time was always near 11 hours. As day-length decreased the smaller daylight bouts were progressively replaced by bouts during darkness. Similar patterns were also found in studies of grazing Holstein/Friesian heifers and of housed non-lactating cows at Moorepark. The primary feature of the grazing pattern is the bout. The bout implies that there is a control that determines when grazing commences and ends. Rumen capacity plays a part but does not explain why minor bouts are only one hour and major bouts are more than 4 hours. The rigid association of the two major bouts with dawn and dusk implies that light also plays a part. That the total grazing time is constant suggests that yet another control is operating that is related to the state of the animal relative to a target state. And this control relates to a 24-hour period. Domestic bovines do not display any patterns of behaviour related to seasonal or lunar cycles. The patterns appear to be circadian and in that case it would not be surprising to find that the suggested light cue was present as a means of measuring the day.EU Structural Funds (EAGGF

Measurement of the Ds lifetime

We report precise measurement of the Ds meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p beams. The measurement has been done using 918 reconstructed Ds. The lifetime of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL

Hadronic Production of Lambda_c from 600 GeV/c pion, sigma and proton beams

We present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for anti-Lambda_c compared to Lambda_c+ as a function of xF and pt2 distributions for Lambda_c+. These data were measured in the same apparatus using incident pi-, sigma- beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of xF. In the forward hemisphere with xF >= 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda_c formation, as suggested by the leading quark picture.Comment: 6 pages, 5 figures (postscript), RevTeX, submitted to Phy. Rev. Let

First Observation of the Cabibbo-suppressed Decays Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+ and Measurement of their Branching Ratios

We report the first observation of two Cabibbo-suppressed decay modes, Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+. We observe 59+/-14 over a background of 87, and 22+/-8 over a background of 13 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600GeV/c Sigma- beam. The branching ratios of the decays relative to the Cabibbo--favored Xi_c+ -> Xi- pi+ pi+ are measured to be B(Xi_c+ -> Sigma+ pi- pi+)/B(Xi_c+ -> Xi- pi+ pi+) = 0.48+/-0.20, and B(Xi_c+ -> Sigma- pi+ pi+)/B(Xi_c+ -> Xi- pi+ pi+) = 0.18+/-0.09, respectively. We also report branching ratios for the same decay modes of the Lambda_c+ relative to Lambda_c+ -> p K- pi+.Comment: 15 pages, 5 figures, version 2 as accepted in PL