Two similar experiments were conducted in consecutive years using a total of 26 pregnant beef cows. The two groups of 13 cows were given 2 kg molassed sugar-beet pulp (SBP)/day for the last 16 weeks of pregnancy and 3 kg SBP/day for the first 6 weeks of lactation with oat straw ad libitum. One group was given 250 g of a fully soluble liquid supplement (LS) containing urea, phosphoric acid, calcium and sodium chloride, trace elements and vitamins poured on to the SBP. The other group received no supplementary phosphorus but was given the same amounts of supplementary nitrogen (as crystalline urea) and calcium (as calcium carbonate) together with the same amounts of sodium chloride, trace elements and vitamins as were present in the LS. The LS provided 3-7 g P/day. The overall mean phosphorus intakes of the two groups were about 5-5 g (unsupplemented) and 10-5 g P (LS)/day. During pregnancy, reduced phosphorus intakes did not affect either the voluntary intake or digestibility of the straw. There was, however, a reduction in the blood phosphorus concentration for the cows which did not receive LS.After calving, the voluntary straw intake, digestibility of straw organic matter, metabolizablo energy intakes and blood phosphorus concentrations of the cows which received no phosphorus supplement were severely reduced. Using the present data and that from an earlier, similar experiment, a highly significant relationship was established between blood phosphorus concentration and voluntary straw intake during the period 5-6 weeks after calving for those cows with a blood phosphorus concentration below 1-0 mmol P/l. This relationship was voluntary straw intake (kg D.M./day) = 1-55 + 5-01 x blood phosphorus concentration (mmol/1).These results, obtained with individually fed, housed cattle, tend to suggest that a total phosphorus intake of only about 10-12 g P/day (of which 3-7 g was in the form of phosphoric acid) was adequate to maintain normal blood phosphorus concentration and voluntary straw intake and digestibility by these beef cows over the last 16 weeks of pregnancy and the first 6 weeks of lactation. This should be contrasted with the results of a similar experiment conducted earlier which clearly indicated that a daily intake of about 12 g P/day derived solely from sugar-beet pulp and oat straw was markedly inadequate. major consequence of severe dietary phosphorus inadequacy is a reduced voluntary intake of The recommended daily minimum intakes of fibrous roughages (e.g. straw) and an accompanying phosphorus for 500 kg cows in late pregnancy and reduction in the digestibility of the dry matter in early lactation (7-5 kg milk/day) given by the (D.M.) consumed. In the short term (3 weeks Agricultural Research Council (1965) of 34 and feeding) in late pregnancy, 400 kg cows given a 38 g P have been reduced to 17 and 23 g P respec-low-phosphorus diet composed of molassed sugartively (Agricultural Research Council, 1980). A beet pulp and oat straw (6g P/day) had similar

Eight pregnant beef cows and four rumen-fistulated cows were given 1·67 kg barley dry matter per day and 5·1 kg chopped oat straw dry matter treated by one of four different methods. The straw treatments (given in a 4 × 4 Latin square design) were (A) nil, (B) sodium hydroxide (25 g/kg straw, dry matter basis), (C) a fully soluble liquid supplement containing urea, calcium, phosphorus, sodium, trace elements and vitamins (40 g/kg straw, dry matter basis), and (D) sodium hydroxide plus liquid supplement. In the absence of liquid supplement 0·3 kg per day of the straw dry matter was not consumed, and with the sodium hydroxide plus liquid supplement treatment the cows would have consumed more straw than was offered. Sodium hydroxide increased the digestibility of the straw organic matter from 0·46 to 0·50 (P <0·05), and this was further increased to 0·53 (P <0·01) for the combined sodium hydroxide plus liquid supplement treatment. The calculated metabolizable energy intakes from straw were increased from 31 (nil) t o 36 by either the sodium hydroxide or liquid supplement treatments (P <0·05) and to 41 by the combined treatments (P <0·001). Sodium hydroxide tended to increase the concentrations of n- and iso-butyric acids in the rumen liquor.

No abstract

1981). The effect of the method of presentation of a concentrated solution containing urea, minerals, trace elements and vitamins on the voluntary intake of oat straw by beef cattle. Animal Production, 33, pp 15-17 ABSTRACT Sixteen Hereford-cross cattle (mean live weight 263 kg) in groups of four were individually given 1-5 kg cubed barley per day with ad libitum access to oat straw. In a 4 x 4 Latin square design (21-day feeding periods) they were additionally given either no supplement (diet A) or lOOg/day of a fully soluble liquid supplement containing urea (equivalent to 1090 g crude protein per kg), calcium, phosphorus, sodium, trace elements and vitamins, presented either in the cubed barley (diet B), in the drinking water (diet C) or in a molasses lick (3 parts molasses :2 parts liquid supplement :1 part water) (diet D). Each method of supplementation significantly increased the mean voluntary straw dry-matter intake from approximately 2-9 to approximately 3-25 kg. Mean blood urea concentrations were significantly increased from approximately 1 0 to approximately 1 -9 mmol/1 by all three treatments. The coefficients of variation for the individual blood-urea values of the cattle when given each of the three treatments were very comparable, indicating that there was a reasonable individual uniformity of intake of liquid supplement irrespective of method of presentation.

The mean daily water intakes of individually penned wether sheep were determined over consecutive 7-day periods. Increased intakes of dry matter and/or crude protein resulted in higher intakes of water. The drinking pattern throughout the day was directly related to the type of food offered and its distribution during the day.