A growing-finishing study using Angus steer calves was conducted in three phases: 1) grazing stockpiled 'Kentucky-31' tall fescue (Festuca arundinacea Schreb.) with high (65%; HE KY-31) and low (0%; LE KY-31) infestation rates of Acremonium coenophialum Morgan-Jones and Gams and 'Kenhy' and 'Johnstone' tall fescue with low (< 1%) infestation rate of Acremonium coenophialum from October 24 to December 19; 2) drylot feeding of Johnstone and HE KY-31 haylage (December 19 to April 10); and 3) feedlot finishing on a common high-concentrate diet (April 11 to August 1). In Phase 1, ADG was greatest (P < .05) for Kenhy, intermediate for Johnstone and LE KY-31, and lowest (P < .05) for HE KY-31. Implantation with estradiol 17-beta increased ADG (P < .01) by 23, 27, 7, and 2% for steers grazing Johnstone, HE KY-31, LE KY-31, and Kenhy, respectively. Dry matter digestibility and DMI of stockpiled Johnstone and HE KY-31 were not different (P > .10). During Phase 2, steers consuming Johnstone haylage had greater (P < .01) DMI, ADG, and gain:feed ratio (G:F) than steers consuming HE KY-31 haylage. During Phase 3, steers previously consuming Johnstone had greater DMI (P < .10); however, steers previously fed HE KY-31 had greater ADG (P < .05) and G:F (P < .01). By the end of the study, steer body weights were not different (P > .10) between treatments. These data indicate that growth-decreasing effects of endophyte-infested fescue were evident at hypothermal-ambient temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of grazing low-endophyte (Acremonium coenophialum Morgan-Jones and Gams, less than 1% infection) Johnstone (J) or high-endophyte (60% infection) Kentucky-31 (K) tall fescue (Festuca arundinacea Schreb.) on grazing behavior and voluntary intake were studied. Six Angus steers (average initial BW = 326 kg) grazed 1.21-ha plots of each forage cultivar (three steers per cultivar) in four 28-d periods beginning May 27. Daytime observations (0630 until 2130) revealed that J steers spent more (P less than .10) time grazing and lying down and took more (P less than .05) prehensile bites than K steers did; conversely, steers grazing K spent more (P less than .10) time standing and idling than J steers did. Idling time showed a forage x period interaction (P less than .10). Mean OM bite size (grams per bite) was not affected (P greater than .10) by forage but differed (P less than .10) among periods. Limited nighttime observations (2130 until 0630) revealed no effects (P greater than .10) of forage on grazing time or number of prehensile bites taken. Voluntary intakes of OM and NDF did not differ (P greater than .10) between steers grazing J and K; however, a forage x period interaction (P less than .10) existed such that, during Period 1, steers grazing J had greater (P less than .01) OM and NDF intakes than did steers grazing K. These data suggest that cattle grazing endophyte-infected tall fescue display altered daytime grazing behavior and that reduction of voluntary intake attributable to endophyte infection may be less severe under free-grazing than has been reported for controlled environmental conditions.

Four crossbred wether lambs (38 kg) with permanent ruminal and abomasal cannulae were used in a 4 X 4 Latin square arrangement of treatments to determine the effect of feeding frequency (FF) on forage fiber and N utilization. Lambs were offered 900 g of good quality (vegetative) Kentucky-31 tall fescue hay in equal portions either 2, 4, 8 or 16 times daily. Water consumption increased (P less than .05; linear) with increased FF. Apparent total tract digestibilities of dry matter, organic matter and cell wall constituents were not affected (P greater than .05) by FF, but apparent total tract digestibility of crude protein decreased (P less than .05; linear) with increased FF. Ruminal and post-ruminal digestion of acid detergent fiber (percent of total tract digestion) differed (P less than .05; cubic) among FF treatments. Although N retention was not affected (P greater than .05) by FF, increased FF decreased (P less than .05; linear) mean ruminal ammonia-N concentrations. Both the quantity of total N reaching the abomasum and the efficiency of microbial crude protein synthesis tended to increase (P greater than .05) with increased FF. In addition, the daily quantity of microbial N reaching the abomasum was affected (P less than .05; cubic) by FF. Ruminal pH was not affected (P greater than .05) by FF, whereas total volatile fatty acid concentrations (VFA) decreased (P less than .05; linear) with increased FF. Responses in molar proportions of individual VFA to FF were variable, and suggest that increasing FF elicits significant changes in the distribution of fermentation end-products.(ABSTRACT TRUNCATED AT 250 WORDS)

. 2004. Current and residual effects of nitrogen fertilizer applied to grass pasture on production of beef cattle in central Saskatchewan. Can. J. Anim. Sci. 84: 91-104. Four rates of nitrogen fertilizer (0, 50, 100 and 200 kg N ha -1 ) were applied for 4 yr to two replications of a 32-yr-old crested wheatgrass (Agropyron cristatum) pasture at Lanigan, Saskatchewan, after which no fertilizer was applied for a further 4 yr. The pastures were grazed by pregnant yearling Hereford heifers using a "put-and-take" stocking system. Soil cores (0-60 cm) were taken to monitor soil NO 3 -N concentrations either in early spring, before grass growth commenced, or in late fall, after grass growth had ceased. Pasture measurements included available forage at the start of the grazing season, total forage production and the concentrations of crude protein, acid detergent fiber (ADF), ash, Ca, P, Mg, K, Cu, Zn, Fe and Mn. Heifers, fistulated at the esophagus, were used in 1984 and 1985 to obtain samples of the grazed herbage, which were analyzed for organic matter digestibility (OMD), protein and minerals, except P and K. Heifer intakes of digestible organic matter (DOMI), protein and minerals, except P and K, were estimated from their concentrations in fistula extrusa and estimates of intake obtained from extrusa digestibility and fecal output using Cr 2 O 3 as a fecal marker. Phosphorus intake was estimated from fecal P concentration. Plasma samples were also collected and analyzed for concentrations of minerals.Soil NO 3 -N concentrations increased during the years of fertilizer application. One year after fertilizer application at 50 kg N ka -1 ceased, soil NO 3 -N was not significantly different from the control (P > 0.05) but soil NO 3 -N concentrations remained elevated for 4 yr following cessation of fertilizer applications on the 100 and 200 kg N ha -1 treatments (P < 0.05). Total forage production was increased by fertilizer application, but the magnitude of the response was determined by the amount of rainfall during the growing season (P < 0.001). Following cessation of fertilizer applications, the forage available at the start of three of four grazing seasons remained elevated by previous fertilizer applications (P < 0.05). Fertilizer increased the number of animal grazing days (AGD) and total livestock production (P < 0.05) in each year of application and in 3 of the 4 yr following withdrawal of fertilizer applications, the degree of the response depended on rainfall, but had no effect on the average daily gain of the heifers in any year (P > 0.05).Fertilizing crested wheatgrass pastures had little affect on the nutrition of the grazing heifers but plant maturation decreased (P < 0.05) the concentrations of most nutrients. The total utilization of nutrients was increased with increasing increments of fertilizer because of the increased stocking rates (AGD). It is therefore suggested that if the benefits of fertilizer application are to be captured it is important to increase the stocking rate. There was evidence of ...

. 1992. Effects of time and level of energy supplementation on intake and digestibility of low-quality tall fescue hay by sheep Can. J. Anim. . Eff'ects of time and level of energy supplementation on forage intake, nutrient digestibility and ruminal pH were investigated with sheep fed low-quality tall fescue hay either alone (control; C) or supplemented (S) with concentrate at 10 (low; L) or 20% (high; H) of ad libitum forage intake; supplement was offered at 08:00 or l5:00 h. Supplementation increased (P < 0.05) digestible dry matter intake (DMI), total tract organic matter digestibility, N intake, and N digestibility, but decreased (P < 0.05) mean and minimum ruminal pH compared with C. Offering supplement at 08:00 h increased (P < 0.05) forage and total DMI, N intake, fecal N excretion and maximum ruminal pH, but lowered (P < 0.05) total tract digestibility of acid detergent fibre (ADF) and organic matter, and mean and minimum ruminal pH compared with 15:00 h. A high level of supplementation increased (P < 0.10) digestible DMI, postruminal digestion of neutral detergent fibre (NDF), and hemicellulose (HC), but lowered (P < 0.0I) ruminal digestion of HC and NDF (P < 0.10), mean ruminal pH (P < 0.i0) and total tract ADF digestion (P < 0.05) compared with L. These data suggest that the substitution effects of concentrate f'eeding on forage intake can be mitigated by changing the time of day when supplement is off'ered in relation to forage. 15 h. La compl6mentation a accru (P < 0,05) la prise de matidre sdche digestible, la digestibilit6 globale de la matidre organique, I'ingestion et la digestibilit6 de N, mais elle a abaiss6 (P < 0,05) le pH moyen et le pH minimum du rumen par comparaison avec le r6gime t6moin. La distribution du compl6ment ir 8 h plut6t qu'ir 15 h a accru (P < 0,05) l'ingestion de foin et la consommation totale, l'ingestion de N, I'excr6tion f6cale de N et le pH maximum du rumen. En revanche, elle abaissait (P < 0,05) la digestibilit6 globale de la lignocellulose (ADF) et de la m.o., ainsi que le pH moyen et le pH minimum du rumen. Au niveau sup6rieur de compl6mentation, on a observd une augmentation (P < 0,10) de f ingestion de matibre sbche digestible et de la digestibilit6 post-ruminale de la NDF et de I'h6micellulose, en mOme temps qu'une diminution (P < 0,10 et P < 0,01) de la digestibilit6 ruminale respective de ces deux groupes de fibres et une baisse du pH moyen du rumen (P < 0,10) et de la digestibilit6 globale de I'ADF (P < 0,05), par rapport au niveau bas de rThis paper