Relationships between dietary and cow factors with the fecal phosphorus contents of dairy cows in Manitoba

A survey was carried out on 19 dairy farms in Manitoba that varied in size, diet composition, housing, and feeding strategy to identify factors that affect the phosphorus (P) content of feces. On each farm, 10 early, 10 mid, and 10 late lactation cows were included. Multiple regression analysis showed that high dietary P concentrations and free-stall instead of tie-stall housing were mostly associated with high P contents of feces. Hence, a closer matching of the requirements and supply of P of dairy cows enhances the utilization of dietary P on these farms.

Evaluating Sucralfate as a Phosphate Binder in Normal Cats and Cats with Chronic Kidney Disease

Control of hyperphosphatemia is an important part of the management of chronic kidney disease (CKD). The purpose of this study was to determine the efficacy of sucralfate as a phosphate binder in normal cats and normophosphatemic CKD cats. A 500 mg sucralfate slurry was administered orally q 8 hr for 2 wk, and serum phosphorus, urine fractional excretion of phosphorus, and fecal phosphorus concentrations were measured. In normal cats treated with sucralfate, significant changes in serum phosphorus concentration or urinary excretion of phosphorus were not detected, and vomiting occurred after 14.7% of administrations. Of the five normophosphatemic cats with CKD treated with sucralfate, three experienced clinical decompensation, including vomiting, anorexia, constipation, and increased azotemia. Administration of sucralfate did not result in significant changes in fecal phosphorus concentration in these cats. The effects of sucralfate administration on serum phosphorus concentration and urinary excretion of phosphorus in CKD cats was difficult to determine because of dehydration and worsening azotemia associated with decompensation. Due to side effects and the apparent lack of efficacy of the medication, the study was discontinued. This study was unable to confirm efficacy of this sucralfate formulation as a phosphate binder, and side effects were problematic during the study.

The effects of phytase supplementation on nutrient digestibility, plasma parameters, performance and carcass traits of pigs fed diets based on low-phytate barley without inorganic phosphorus

A total of 80 crossbred pigs (25.5 ± 2.6 kg) were assigned to one of eight dietary treatments. A positive control, based on Harrington barley, was formulated to meet requirements for total phosphorus. Three experimental diets (low in total phosphorus) were formulated based on either Harrington barley (0.28% phytate phosphorus) or the low phytate genotypes LP422 (0.14% phytate phosphorus) and LP 635 (0.09% phytate phosphorus). The four diets were fed with and without 1000 FTU kg-1 phytase. Calcium and phosphorus digestibility were significantly higher (P < 0.05) as a result of supplementation with phytase. For the barley diets formulated without dicalcium phosphate, calcium digestibility averaged 69.6, 73.3 and 72.2% while phosphorus digestibility averaged 36.5, 50.5 and 57.7% for pigs fed the Harrington, LP 422 and LP 635 diets, respectively. The addition of phytase to the diet consistently reduced the percentage of phosphorus excreted in feces and fecal phosphorus excretion declined as the level of phytate in the barley declined. The addition of phytase tended to improve weight gain (P < 0.10) and significantly improved feed conversion (P < 0.05). For pigs fed the barley diets formulated without dicalcium phosphate, daily gain averaged 0.90, 0.99 and 1.01 kg d-1 while feed conversion averaged 2.70, 2.39 and 2.38 for the Harrington, LP 422 and LP 635 diets, respectively. The overall results of this experiment indicate that the performance of pigs fed diets containing low-phytate barley formulated without a source of inorganic phosphorus is at least equal to that of pigs fed diets containing normal-phytate barley and inorganic phosphorus. In addition, the increased availability of organic phosphorus reduced the amount of phosphorus excreted thus reducing the amount of phosphorus that can potentially pollute the environment. Key words: Low phytate barley, phytase, pigs, performance, digestibility

Additivity of apparent ileal and fecal phosphorus digestibility values measured in single feed ingredients for growing-finishing pigs

Two experiments were conducted to determine apparent ileal and fecal P digestibility values in barley, wheat, peas and canola meal and to examine whether the apparent P digestibility values measured in single feed ingredients are additive when used in diet for mulation for growing-finishing pigs. In both experiments, five barrows, with average initial body weights of 40 and 35 kg, were fitted with a simple T-cannula at the distal ileum and fed five diets according to a 5 × 5 Latin sq uare design. In exp. 1, the barrows were fed five diets (diets 1, 2, 3, 4, and 5) formulated to contain five graded levels of barley (0, 22.5, 45.0, 67.5 and 90%, respectively) and canola meal (42.7, 36.6, 30.5, 24.4 and 0%, respectively). In exp. 2, the barrows were fed five diets (diets 1, 2, 3, 4, and 5) formulated to contain five graded levels of wheat (88.5, 66.4, 44.3, 22.1 and 0%, respectively) and peas (0, 16.8, 33.6, 50.4 and 67.1%, respectively). Chromic oxide (0.4%) was used as a digestibility marker in both experiments. The pigs were fed twice daily, at 0800 and 2000. The dietary allowance was 1800 g d-1. Each experimental period lasted 8 d. Representative fecal samples were collected during days 5 and 6. Ileal digesta were collected for a total of 24 h, at 2-h intervals, during days 7 and 8. The ileal and fecal P digestibility values in barley, wheat, peas and canola meal were associated with large standard errors, suggesting a large variability within each feed ingredient. There were no differences (P > 0.05) between the directly determined and predicted apparent fecal P digestibility values in diets 2, 3 and 4 of exp. 1. However, there were differences (P < 0.05) between the directly determined and the predicted apparent fecal P digestibility values in diets 3 (46.5 ± 1.0 vs. 38.7 ± 0.6) and 4 (48.2 ± 1.2 vs. 41.6 ± 1.2) in exp. 2, indicating that apparent fecal P digestibility values are not always additive in diet formulation. It is concluded that apparent P digestibility values are variable and not very reliable in diet formulation for swine. Key words: Phosphorus, digestibility, feeds, pigs