Two metabolism trials were conducted with 12 crossbred wether lambs, each surgically equipped with a ruminal catheter and abomasal and ileal cannulae, to study the effect of K infusion in different sites of the digestive tract on site of absorption and flow of minerals. The treatments consisted of the infusion of 33.6, 12.0 or 12.0 g K/d as bicarbonate into either the rumen, abomasum or ileum, respectively. Each trial consisted of a minimum 5-d preliminary period, five 3-d collection periods to determine mineral balance and a 6-d sampling period to determine mineral flow and site of absorption. Chromic oxide was incorporated into the diet for use as a marker. Magnesium was absorbed primarily from the preintestinal region. Ruminal infusion of K tended to decrease preintestinal Mg absorption. Absorption of Mg in the entire tract was decreased (P less than .05) 43% when K was infused into the rumen. There was a slight absorption of Mg in the small intestine, followed by a net secretion into the large intestine. Serum Mg levels tended to be depressed in lambs infused with K intraruminally. Calcium flow from the preintestinal region was decreased (P less than .05) by infusion of K into the rumen. Only lambs infused with K in the rumen had a net secretion of Na into the small intestine. The large intestine was the primary site of net Na absorption for ruminal-infused lambs. Phosphorus flow from the preintestinal region was decreased (P less than .05) by infusion of K into the rumen. Potassium flow from both the preintestine and small intestine was increased (P less than .05) by ruminal K infusion. The infusion of K into the rumen, abomasum or ileum increased (P less than .05) the total absorption of K, with the small intestine being the major absorptive site. The infusion of potassium bicarbonate into the rumen of sheep raised (P less than .05) the pH of the ruminal contents 15%. Ruminal infusion of K depresses Mg absorption, while the infusion of K into the abomasum or ileum does not affect Mg absorption. Therefore, the role of K in grass tetany may be via this depression of Mg absorption.

An experiment was conducted to investigate the compartmental mean residence time, (CMRT) of feed residues in segments of gastrointestinal digesta of mature Holstein steers. The objective was to evaluate assumptions that feed residues flow through ruminal digesta as sequential mixing pools having age-dependent (GN) and age-independent (G1) distributed residence times respectively (GN → G1 flow). The basal diet was a semi-tropical hay containing 98 g crude protein and 503 g apparently digestible DM per kg DM. The hay was consumed and feed residues of different size and/or previous digestion from the hay were inserted into the reticulo-rumen (rumen) and abomasum. Marker profiles appearing at the duodenum and faeces were fitted to various compartment models to estimate CMRT. Post-abomasal CMRT did not differ among solutes or feed residues of different size and previous digestion and constituted only 5⋅8 % of the CMRT for the entire gastrointestinal tract. Markers initially applied to orally or ruminally dosed feed residues exhibited profiles in duodenal digesta and faeces conforming to GN → G1 flow. Previously undigested, masticated feed residues inserted into the dorsal rumen digesta had longer ruminal CMRT in the GN pool but not the G1 pool than did similarly inserted faecal small particles or normally ingested hay. These results support model assumptions of GN → G1 flow within rumen digesta. The results support mechanisms proposed for the GN pool as the 'lagrumination pool' and the G1 pool as the 'mass action turnover pool'. If further validated, rumen CMRT in cattle could be estimated from marker profiles in more easily obtained faeces to estimate ruminal CMRT required for feed evaluation systems. Compartmental models: Digesta flow: Forage particle sizeThe compartmental mean residence time (CMRT) of feed residues in the digesta of the reticulo-rumen (rumen) is determined by various forces that constrain and propel ruminal escape of undigested feed residues. A major force constraining escape is the competition among ingested feed residues with resident residues of previous meals as the result of the continual mixing of ruminal digesta. If this competition for escape is passive for all feed residues, regardless of their attributes or age in the pool, then CMRT is a function of the mass of resident feed residues and the continued intake rate of feed residues, i.e. mass action dilution turnover rate of the continued intake. Matis (1972) observed that newly ingested feed residues require ageing before acquiring properties required for escape, properties such as particle size reduction for example. Matis (1972) proposed an age-dependent distribution of residence times to model this initial process constraining escape in contrast to an age-independent, mass action turnover. The age-dependent turnover of undigested feed residues in ruminal digesta could be modelled as a single agedependent mixing pool or a sequence of age-dependent → age-independent mixing pools. Ellis et al. (1991Ellis et al. ( , 1994 proposed the 'un-...

The validity of using rare earth elements as flow markers of undigested residues was evaluated by comparing mean gastrointestinal residence time (GMRT) of rare earths specifically applied to cottonseed hulls (CSH) to that of the indigestible fiber of CSH. Feces were collected from five lambs fed a mineral supplemented diet of CSH containing 52 g CP/kg DM and five lambs fed a CSH plus cottonseed meal diet (CSH+CSM) containing 123 g CP/kg DM. Rare earth elements (La, Yb, and Tb) specifically bound to CSH were included in the diet for a 5-d period and then deleted from the diet for a 3-d period. Following the last fecal collection, lambs were slaughtered for collection of digesta from segments of the gastrointestinal tract. Potentially indigestible NDF (PIF) was determined in diets and digesta from each segment of the gastrointestinal tract. Mean turnover rate, time delay, and GMRT for each rare earth element was estimated by fitting an age-dependent compartment model to profiles of markers appearing in the feces (compartmental model-marker method, CMM). The GMRT also was computed by the indigestible entity pool dilution method (IEPD) as grams of PIF in sampled segment/mean intake rate of PIF proceeding slaughter, g/h. The GMRT computed by the CMM and the IEPD methods did not significantly (P < 0.05) differ (99.6 vs 94.8 h and 58.9 vs 59.5 h for CMM vs IEPD and CSH and CSH+CSM diets, respectively). Regression of GMRT estimated for rare earths vs PIF yielded a highly significant regression (P = 0.001) with a regression coefficient of 0.94 +/- 0.016. It was concluded that rare earth elements applied to specific feeds are valid flow markers for the undigested residues derived from such marked feeds.

Private voluntary social welfare organizations (PVSOs) are operating under increasingly competitive conditions. "Strategic Planning" (SP) is a management tool designed to meet those conditions. In an exploratory study of 154 PVSOs the authors examined management's reasons for adopting strategic planning, the attention given to external analysis, and the degree of change and satisfaction achieved. PVSOs use SP because they are required/urged to do so by external agencies. External analysis received the least attention. One-half of the organizations achieved major change which was associated with high levels of satisfaction. Widespread stakeholder participation and the use of consensus strategies detracted from both major change and high satisfaction outcomes.

Two experiments were conducted to measure effects of source and level of roughage on the flow of corn residues through the gastrointestinal tract of cattle. In Exp. 1, steers (195 kg) were fed diets of ground corn with 0,30 or 60% of ground Coastal bermudagrass hay (Cynodon dactylon) K.3 Pers.) at intakes of 1, 1.5 or 2% of BW in a 9 x 9 Latin square. Experiment 2 consisted of two 4 x 4 Latin squares with either rice hulls (square 1) or ground Coastal bermudagrass hay (square 2) providing 0, 7.5, 15 or 30% of the total diet fed at 1.5% of BW. After a 28-d adjustment period, a portion of the corn in one meal was replaced with cracked corn stained with brilliant green. The concentrations of stained corn residues appearing in the feces subsequent to dosing were fitted to a onecompartment, agedependent model and compartmental mean residence time (CMRT) and time delay (7) were estimated. In Exp. 1, increasing the level of intake of the ration from 1 % to 1.5 or 2.0% of BW increased (P c .05) CMRT by 52% and reduced (P < .05) z by 41%. In Exp. 2, source of roughage had no effect (P = .95) on CMRT or 2. Combined results of the two experiments indicated that increasing proportion (P) of either roughage was associated with an exponential decline in CMRT of stained corn residues (CMRT = 121.1 * e-.0315q from rations consumed at 1.5 and 2.0% of BW. No consistent effect of roughage type or proportion was noted on time delay in the two experiments collectively. These results indicate that increasing the proportion of roughage in the diet exponentially reduces residence time of corn residues in the ruminoreticulum (CMRT) without affecting residence time in the postgastric segments (7).