Eight soil Mn tests, namely, CH3COONH4-, Mg(NO3)2-, H3PO4-, hydroquinone-, 3m-NH4H2PO4-,1·5m-NH4H2PO4- and EDTA-extractable Mn and total Mn were evaluated for their ability to predict Mn uptake by maize (Zea mays L.) on 63 soils of diverse origin. Regression equations were derived by comparing Mn uptake with each test in combination with pH. The best prediction of Mn uptake was provided by a combination of CH3COONH4-extractable Mn and pH; 52·9 % of the variability in Mn uptake was accounted for by these two variables. EDTA and H3PO4-extractable Mn were superior to the other soil Mn tests in predicting Mn uptake.

The effect of soil properties on the extractability of soil Mn by each extractant was analysed statistically. Only with hydroquinone-extractable Mn did the soil variables investigated account for a major portion of the variability in the Mn test. The soil variables most often correlated significantly with the Mn test were pH and total Mn. Organic carbon and clay contents were significant only in determining EDTA- and Mg(NO3)2-extractable Mn, respectively.

The environmental and genetic control of reproductive growth was studied in S. 170 a variety of Festuca arundinacea Schreb. The variety had induction requirements for short days and low temperatures before inflorescence production could occur, but some genotypes became induced with only short-day treatments. Low temperatures and short days in controlled environment rooms were less effective in bringing about induction than winter conditions in an unheated glasshouse. Only non-additive genetic effects could be shown to be significant in the control of induction requirements. Field studies showed that all inflorescence characters were subject to genetic and genetic x environmental control, and they also indicated that seed weight per inflorescence and seed fertility were most likely to show a response to selection. Diallel analysis under glasshouse conditions showed that the seed fertility and 1000 seed weight of the parental crosses were subject to maternal control, but these effects were not detectable in the next generation. Genetic control of seed fertility and 1000 seed weight in the diallel progeny was mainly additive.

Complete diets were given ad libitum to dairy cows over a whole lactation in order to study the voluntary intake of food, lactation performance and efficiency of feed conversion. The effect of including four levels 16, 24, 32 and 40 % of coarsely milled barley straw in the loose mix was studied for diets based mainly on barley or on sugar beet pulp, using a double 4 × 4 Latin square design.

The results confirmed that cows can perform normally when given complete diets for extended periods. Dry matter and digestible energy intake was depressed at the higher levels of straw inclusion and milk butterfat content at the lowest level. The net efficiency of conversion of metabolizable energy (M.E.) into milk was higher at the higher levels of straw. It is concluded that complete diets for the self-feeding of dairy cows should contain a minimum of about 24 % of coarsely milled straw and that estimated metabolizable energy intake and production were depressed by including straw at higher levels.

The components of yield were studied in a local strain of field beans (Baladi) and two Egyptian varieties (Rebaya 40 and Giza 1). Although no significant differences between varieties were detected in yield per plant, there were differences in components of yield. The Egyptian varieties produced heavier seeds but less pods and seeds than the local strain. The higherpod number in Baladi resulted from a capacity to produce more pods per stem rather than from anability to produce more stems per plant.

Correlations between yield and other plant characters and between components of yield were computed. The path-coefficient analysis was employed to partition the correlation coefficients and to compare the relative importance of the primary yield components in predicting yield. Pods per plant showed the highest correlation with yield and selection for high yield can be based on it. Seed weight was negatively associated with pod number and seeds per pod but the r values were too low to be of predictive value. Multiple correlations indicated that 95–98% of the variability in yield was accounted for by the components pod number, seeds per pod and seed weight.

Eighty-nine lactating sows, which had farrowed at least once before, were given 140 injections with 2000, 1800 or 1500 i.u. pregnant mare serum hormone. Seventy sows served as controls. 124 injections with 2000 i.u. P.M.S. were followed by 113 oestrus reactions and 88 pregnancies, and 16 injections with 1800 or 1500 i.u. by eleven instances of oestrus and six of pregnancy.

Oestrus occurred in 69% of the positive reactors on the 5th day after injection, and in the rest either earlier or later. The interval between the P.M.S. injection and the onset of oestrus was similar to that between weaning and oestrus in the controls.

The difference between the pregnancy rate of 71% following injection with 2000 i.u. P.M.S. and that of 83% in the control sows from the first oestrus after weaning was found to be statistically highly significant.

Mean litter size and weight were not affected by different time intervals between farrowing and P.M.S. injection, nor were there any statistically significant differences in size and weight of litters at birth or at weaning at 8 weeks of age between those of hormonally treated sowsand the controls.

The shortening of the farrowing interval by P.M.S. injection had no after-effect on the sizeand weight of litters subsequently obtained with or without hormone application.

Injections with 1800 or 1500 i.u. P.M.S. were followed by a reduced pregnancy rate, but the few litters thus obtained were similar in mean size and weight to those obtained with 2000 i.u.or those of the controls.

Sows that did not come on heat or become pregnant following P.M.S. injection came into heat at the same times after weaning of their litters as the control sows.

The shortening of the farrowing interval by an average of 22 days was considered to be of sufficiently high economic value to warrant the introduction on the farm where the experiment wasconducted of the routine application of 2000 i.u. P.M.S. to all gilts and sows on the 28th day after farrowing.

A subclinical calcium or phosphorus dietary deficiency on many hill pastures and a relationship between this and the premature loss of permanent incisor teeth are postulated. The effects of small individual supplements of calcium (12 g calcium carbonate suspended in water) or phosphorus (13 g monosodium phosphate in solution) supplied three times a week between mid-February and the end of May to Scottish Blackface ewes which grazed reseeded pasture in April and May were compared with those of no mineral supplement and with those of no mineral supplementon hill pastures throughout.

Neither supplement had any significant effect on the number or weights of lambs born or reared on reseeded pastures. Both resulted in significantly greater ewe live-weight gain during the treatment period, in a significant improvement in the firmness and permanence of the incisor teeth, and in significantly higher serum Ca levels during lactation. All effects increased with advancing age.

The use of hill pastures during late pregnancy and early lactation without any mineral supplement could result in significantly poorer ewe live-weight gain during the treatment period depending on season. This was also associated with significantly lighter single lambs at 6 weeks and with slower deterioration of the incisor teeth.

It is suggested that minerals lost from the body during lactation on reseeded pastures are not replaced during the autumn recovery period on hill pastures and that a gradual depletion occurs throughout life, leading possibly to demineralization of the alveolar bone and premature loss of the incisor teeth. It is suggested that this is indicative of a higher mineral requirement for maintenance of the permanent dentition than is necessary for normal acceptable growth andreproductive performance. Mineral content of hill herbage may therefore be too low to supply requirements at the levels of OM intake normal on hill pastures.

A total of 512 pigs were given from 50 lb live weight one of 16 diets, i.e. with 4 lysine levels at each of 12, 14, 16 and 18% protein, at one of 4 levels of intake. They were killed at 100, 150, 200 or 250 lb live weight.

Live-weight gain was not improved significantly by increasing the protein level above 16, 14, 12and 12%, respectively, for the 50–100, 100–150, 150–200and200–2501bstages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the protein to 18%. Gain in lean meat and in the efficiency of conversion of feed to lean meat were improved by increasing the above protein levels slightly.

Live-weight gain was not improved significantly by increasing the lysine level above 1·04, 0·74, 0·70 and 0·59%, respectively, for the 50–100, 100–150, 150–200 and 200–250 lb stages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the lysine level to 1·22%. Raising the lysine level at each level of protein had no significant effect on the rate and efficiency of lean meat gain.

Live-weight gain was significantly improved by increasing the level of feed intake almost to ad libitum levels for the 50–100, 100–150 and 150–200 lb stages. There was a suggestion of a similar effect in the 200–250 lb pigs although it was not statistically significant. Conversion of feed to live-weight gain was improved in the 50–100 lb pigs only by increasing the level of feed intake: in the older pigs increasing the level of feed intake caused a worsening in feed conversion ratio. Increasing the level of feed intake gave a significant improvement in rate of lean meat gain but a significant worsening in the efficiency of conversion of feed to lean meat during all stages up to 200 lb.

Interaction effects of these factors and sex, on growth performance, are described.

Yields of maize and cotton given N, and sometimes K but no P, were related to equilibrium values of the monocalcium phosphate potential (½pCa+pH2PO4)eq', at which P is neither lost nor gained by the soil. The responses to phosphate fertilizer were not clearly related to phosphate potentials though small responses at large values of (½pCa+pH2PO4)eq were sometimes explained by very small values of δI/δQ (the rate of change of ½pCa+pH2PO4with change in the amount of P on the soil) or by soil reaction. In only one set of maize experiments, response to P was related to δI/δQ. (½pCa+pH2PO4)0 and (pH2PO4)0', determined without adding P to the solution, were equally useful and both were just as well related to yields without P as (½pCa+pH2PO4)eq' (pH2PO4)0 appeared more useful than the logarithm of the total P concentration measured without added P. It wa not necessary to find the equilibrium phosphate potential, or to measure Ca concentration, but correcting the phosphate concentration for pH (so that only H2PO4-ions were taken into account)was worth while.

Two field experiments have been conducted to investigate the pattern of tillering, ear emergence and survival of the component tillers of three barley varieties, representing old and new varieties. The varieties were grown under contrasting nitrogen fertilizer levels and plant spacings. The results reported are for the variety means and variety x nitrogen and variety x spacing interactions. After the main stem (M) the most frequently occurring tiller was the tiller appearing in the axil of the first true leaf (T2), followed by the coleoptile node tiller (T1) and the tiller in the axil of the second true leaf (T3). The T1 tiller occurred most frequently in the newest variety, Deba Abed, and least in the oldest one, Spratt Archer. Survival rates of the shoots were highest in M, followed by T2, T1 and T3. Higher-order tillers occurred relatively infrequently and had low survival rates. M contributed the largest percentage of the grain yield, followed by T2, T1 and T3. The 13% grain yield advantage of Deba Abed over Spratt Archer was mainly accounted for by the difference in production by the T1 tiller. The results are discussed in. relation to the only other known paper on component tillers in barley.

Controlled-environment experiments showed that development of the coleoptile node tiller (T1) was suppressed much more than that of the tiller appearing in the axil of the first true leaf (T2) by high temperature (24/15 °C; 19/10 °C; 10/6 °C), by reduced photoperiod (16 h; 12·5 h) or by low light intensity (1100 ft-c; 1000 ft-c), but minimally in the newest variety, Deba Abed. Unlike previous field experiments, the T1 tiller appeared on more Spratt Archer than Maris Badger plants. Maris Badger plants produced more T1 tillers in a high-low temperature regime (19/10 °C; 10/6 °C) than in continuous low temperature (10/6 °C). In a field experiment T1 tiller number (and yield), but not the number of other major shoots, were severely reduced by late sowing of Spratt Archer, progressively reduced in Maris Badger, but minimally in Deba Abed. This seemed to be associated with higher temperatures at later sowings.

The effect of nitrogen fertilizer and irrigation treatments on the leaf-area index (L) and net assimilation rate (E) of a monthly cut sward of Italian ryegrass (Lolium multifolium) is considered.

Response to nitrogen was due to increase in both L and E, whereas response to irrigation was largely due to increase in L.

The data show little evidence of a seasonal decline in E. This may have been due to the mid-season replacement of old tillers by new, and by the encouragement to new leaf production caused by periodic harvesting.

Fifty-nine Mutton Merino and cross-bred 2-year-old and older ewes were allotted to two groups according to age, weight and breeding performance in the preceding 1966/67 in-season. In the experimental ewes the treatment started on 22 March 1967 and consisted of vaginal sponges (Syncro-Mate) inserted for 17 days and 750 i.u./ewe of P.M.S. injected on the day of the removal of the sponges.

As from 1 March, all the ewes were ‘teased’ daily but hand service commenced on 20 April, to coincide with the 13th day after the removal of the sponges.

At the time of sponge insertion, approximately a third of the ewes, in each group, were already cycling. The treatment advanced the average post-treatment oestrus by 8 days, out of a possible 15 days, synchronized it in 70% of ewes and shortened the tupping season in 97% of treated ewes to 9 days (23 days in controls), but otherwise the performance of the treated ewes (and their offspring) did not differ from that of the controls. In both groups forty ewes lambed (68%) and fifty lambs were born (85%). Out of nineteen dry ewes, five were in anoestrus and in at least nine, an early death of the embryo could be suspected. Among the reproductive activities during the preceding in-season, date of weaning, days of suckling and barrenness may be implicated in the failure to breed in the spring.

Subjectively assessed body condition scores, determined on the live animal, were related to the percentages of chemical fat in the fleece-free empty bodies of 30 adult Scottish Blackface ewes. The results show that body condition scores can provide an acceptable and useful estimate of the proportion of fat in the live animal, and that the level of prediction is superior to that afforded by live weight.

Calcium metabolism in dairy cows has been studied at three periods, namely 2 weeks before and 2 weeks after parturition, and also at peak lactation. Of the four parameters studied—percentage absorption from the diet, endogenous excretion, exchangeable pool size and bone accretion rate—only the last showed significant changes, falling at parturition and rising to pre-calving levels subsequently. There was no increase in the percentage absorption of calcium from the diet after calving but total calcium absorption rose because of increased dietary intake.

Investigations into the non-protein nitrogen composition of grass silages using the 50 cm strong cation-exchange column of Spackman, Stein & Moore (1958) to determine the basic amino acids led to difficulties in the determination of ethanolamine in the presence of high concentrations of ammonia, and of histidine in the presence of δ amino-n-valeric acid. An alternative technique for the ion exchange chromatography and estimation of histidine, lysine, ornithine, ethanolamine, arginine and ammonia on a weak cation-exchange resin has been developed. This method enables small amounts of ethanolamine to be determined in the presence of large amounts of ammonia and values for the ethanolamine content of a number of silage samples are presented. When used in conjunction with the technique of Spackman et al. (1958) the δ-amino-n-valeric acid content of grass silages could also be determined in the presence of histidine.

The estimation of amines produced by the microbial decomposition of herbage proteins during ensiling has previously involved their initial separation from the amino acids followed by quantitative partition chromatography. An alternative method for the estimation of these amines by ion-exchange chromatography on a weak cation-exchange resin is described. This method permits the colorimetric determination of β-phenylethylamine, tyramine, tryptamine, 5-hydroxytryptamine, putrescine, cadaverine and histamine without interference from the amino acids. The efficiency of this technique has been investigated using standard solutions of the naturally occurring amines and samples of good quality and of high pH spoilt silages.

In an experiment to investigate growth in relation to nitrogen concentration and nitrogen uptake, Proctor was compared with four other varieties of barley at two levels of irrigation and two levels of nitrogen fertilizer by means of weekly samples throughout the growing season. The varieties were Deba Abed, a new variety recommended for high fertility conditions where feeding quality grain is required, and three exotic varieties, chosen for their high concentration of nitrogen in the grain.

Irrigation stimulated tillering, although certain varieties responded more strongly than others; irrigation also led to a higher specific growth rate. Certain of the exotic varieties had high growth rates early in the season but growth fell off earlier due to earlier ear emergence. Maximum leaf area index was greater in the irrigated treatment at the high nitrogen fertilizer level. The adapted varieties had higher maximum leaf area indices than the exotic varieties, although some of the exotics had higher rates of leaf area growth early in the season; there were also differences in the way in which the varieties responded to irrigation. Irrigation and variety both affected the rate at which the percentage nitrogen in the shoot fell with time.

Analysis of these data indicates that nitrogen uptake early in the season was an important factor determining the total amount of nitrogen taken up by the plant. It was also shown that the relative rate of decline of the specific growth rate and the specific rate of nitrogen uptake differed between varieties. Analysis of the specific growth rate indicated that differences in leaf growth, rather than net assimilation rate, led to the varietal differences. The differential response to irrigation is discussed with reference to drought resistance.

A method of establishing indwelling catheters in the jugular vein and carotid artery of the pig by way of the blood vessels of the ears is described. The methods used to maintain these catheters patent for long periods are also detailed.

Experiments to determine the net availabilities of the metabolizable energy (NAME) of a cereal-based diet and a maize-oil diet for maintenance and lipogenesis and the effect of environmental temperature on the NAME of the cereal-based diet are described. Four 1- to 2-year-old Light Sussex cockerels were used.

The relationship between ME intake and energy retention was linear for each diet. The NAME'S of the cereal-based diet given at 22° and 28 °C (70.6 ± 1.83 % and 73.6 ± 3.54%, respectively) were significantly (P < 0.05) lower than the NAME of the maize-oil diet (84.1 ± 1.85%). It is concluded that the beneficial effect of maize oil on the efficiency of energy utilization is due to a reduced heat increment rather than a reduction in the basal component of the heat production. The higher efficiency from the maize-oil diet led to an increase in the energy retained as fat.

The mean fasting heat production at 28 °C was 15 % lower than at 22 °C (43.2 ± 1.45 and 51.2 ± 1.09 kcal/kg/day, respectively). The NAME of the cereal-based diet was not significantly different when the birds were kept at 22° or 28 °C. The lower metabolic rate at 28 °C was reflected in a lower maintenance requirement and in an increase in the deposition of body fat.