An experiment was carried out to study the effect of early weaning on body weight and growth rate of Awassi lambs raised at Abu-Ghurib Experiment Station, Baghdad, Iraq. Sex, type of birth and weaning age significantly influenced the body weight and growth rate of lambs at all the ages studied. Dam's age and weight at lambing, however, did not affect the growth rate of the lambs. The average body weights of lambs at 4 and 6 months of age were 23·8±0·28 and 32·3 ± 0·36 kg. The average daily gain in weight up to 120 and 180 days of age was 162·3 ±2·57 and 153·7 ±1·94 g/day respectively. Males were heavier than females and singles were heavier than twins at all the ages. Lambs weaned at 60 days of age were heavier and had a faster growth rate than those weaned at 90 or 120 days of age. Males born to 2-year-old dams grew fastest while the females born to them had the lowest body weights and growth rate.

Seven non-pregnant Murrah buffalo heifers aged 20–34 months and weighing 170–260 kg were used in a 7 × 4 incomplete latin square design to study the effect of feeding mixed diets on voluntary intake over a period of 84 days. Voluntary intake and rate of passage were determined during the last 10 days and digestibility of feed nutrients during the last 6 days of each 21-day experimental period.

Maize stover, dry grass and wheat straw were fed ad libitum mixed with either a fixed quantity of berseem hay (MH, GH and WH rations, respectively) or concentrates (MC, GC and WC rations, respectively) to total co. 0·80% of body weight (BW). Berseem hay fed free choice mixed with limited (0·70% BW) concentrates (HC ration) comprised another treatment. The mean daily total dry-matter intake (DMI g/kgW0·75) and total digestible nutrient intake (given in parenthesis) by animals were 62·2 (1·94), 72·2 (2·20), 74·3 (2·30), 75·2 (2·94), 79·5 (2·59), 85·9 (2·78) and 88·5 (2·98), respectively on MH, GH, WH, HC, MC, WC and GC rations. The digestible crude protein intake on the HC ration was higher than on the remaining six rations. Feeding a fixed quantity of either berseem hay or concentrates resulted in lower consumption of basal roughages suggesting that the physical capacity of the gut limited intake.

Dry-matter digestibility (%) and mean retention time (h), given in parenthesis, were 57·6 (69·4), 56·3 (64·6), 56·7 (67·5), 72·2 (79·9), 59·2 (620), 59·4 (620) and 58·9 (66·0), respectively on MH, GH, WH, HC, MC, GC and WC rations. The digestibilities of D.M. and proximate principles, except crude fibre (CF), of the HC ration were higher than those of the remaining six mixed diets. Concentrate feeding tended to hasten the movement of digesta of the roughage portion of the mixed diet through the digestive tract. The longest mean retention and rumen retention times were associated with the highest digestibilities. The wheat straw-berseem hay mixed diet was as good as dry grass or maize stover-berseem hay mixed diets with regard to its nutrient intake and weight gain by the heifers.

1. Series of yields (root weight) of twenty-five plots of Barnfield mangold field are analysed into components representing (a) deterioration, (b) slow changes other than steady deterioration, (c) annual fluctuations. The two first of these components are exhibited graphically from 1876 to 1930.

2. Yields are well maintained on the dunged strip, except for the last few years. This falling off does not appear in the other strips, and may be due to a falling off in the quality of the farmyard manure in the last five years.

3. On the strip receiving farmyard manure and on that receiving superphosphate the plots receiving nitrate of soda yielded more highly than any others; on the strips receiving complete minerals, and on that receiving superphosphate and potash, the two plots receiving rape cake in one case, and sulphate of ammonia and rape cake in the other, gave higher yields than nitrate of soda; on the strip receiving no minerals the result is intermediate, there being little to choose between these three plots. On all strips sulphate of ammonia is the least satisfactory of the four nitrogenous dressings tested.

Copper has been detected in a large number of plants, and is probably present in very minute amounts in all vegetation. Estimations of copper content of a number of plants have been made, notably by Fleurent and Levi(1), Maquenne and Demoussy(2) and McHargue(3).

The genetic parameters of lifetime production traits and their relationship with milk yield in first, second and third lactations were estimated from information on 753 Tharparkar cows. The heritability estimates for milk yield in first, second and third lactations were 0·22 ± 0·10, 0·33 ± 0·14 and 0·49 ± 0·17 and for number of lactations completed, lifetime milk production, number of days in milk and herd life 0·58 ± 0·23, 0·51 ± 0·22, 0·54 ± 0·22 and 0·34 ± 0·20 respectively. The genetic and phenotypic correlations among the four lifetime production traits were in the range of 0·83–1·0 and 0·84–0·85 respectively. The phenotypic correlations of milk yield in first, second and third lactations with lifetime production traits were significant and ranged between 0·15 and 0·56. The corresponding genetic correlations ranged between 0·26 and 0·83. For the first three lactations, the genetic correlations of lifetime traits with the third lactation were high and that between lifetime milk yield and yield in third lactation the highest (0·83 ± 0·17). The direct and correlated responses from single trait selection were also estimated.

Evans & Roberts (1979) considered that loworder polynomials such as mean, linear and quadratic were adequate to describe the trends that occur in treatment contrasts in long-term agricultural experiments. This conclusion was based on experience with experiments on levels of fertilizers and rates of stocking on similar pastures. In such experiments, the marked seasonal pattern in the data disappears when comparisons between treatments are followed. However, further experience with experiments comparing cultivars has shown that some comparisons still show a seasonal pattern. Such patterns may be accounted for by periodic regression (Bliss, 1970).

Low quality roughages are a major feed resource for ruminants in Australia and many other parts of the world. Factors limiting the intake of these roughages include their high cell wall component and low crude protein content. Palatability may also be important. Low quality roughages are frequently dusty. Hence, the present experiment was initiated to determine whether water would affect the intake of paspalum hay (Paspalum dilatatum).

The gross energy of forages can be classified into three fractions, namely the unavailable fraction, the digestible energy fraction and the potentially digestible energy (PDE) fraction. The PDE fraction can only be made available by appropriate treatment and supplementation (Pigden & Heaney, 1969). In young forages the PDE fraction is relatively insignificant, but as the plant matures, the PDE fraction increases very rapidly. By treating matured forages with delignifying agents, increased nutrient digestibilities have been demonstrated Chandra & Jackson, 1971; Wilson & Pigden, 1964), but no significant improvement on the voluntary intake was achieved unless the treated material was supplemented with a source of nitrogen (Donefer, Adeleye & Jones, 1969). While Zafren (1960) used ammonium hydroxide (NH40H) as the treatment alkali, with the claim that the ammonium acetate resulting from the neutralization of the excess alkali could serve as an extra source of nitrogen in the treated straw, other investigators (Donefer et al. 1969) have adopted the method of supplementing the treated straw with a source of nitrogen. Since the efficiency with which dietary nitrogen is converted to microbial nitrogen in the rumen has a considerable influence on the efficiency the animal as a whole, studies herein reported were carried out to test the effectiveness with which rumen micro-organisms utilize different nitrogen sources in degrading cellulose in vitro.

Coles (1957) has reported the results of a hatchability trial in which four pens of hens each received 10% of a different sample offish meal (A–D) in their diet as the only experimental variable. There was a high level of egg production in each pen, but differences in hatchability as indicated in Table 1. The pen with lowest hatchability received fish meal D, which was darker in colour than the others. It was suggested that this might indicate a scorching of the meal with heat damage, and that in turn this might be responsible for the lower hatchability. The meals have now been analysed to investigate this point.

is generally used to describe the lactation curve in cattle, where yn (kg) is the average daily milk yield in the nth week of lactation (n = 1, 2, 3, …, N), a is a scale parameter, and b and c are shape parameters. The model was first proposed by Wood (1967) and is widely used in practice to describe the lactation curve for fat, protein, lactose and wholemilk production; it has also been used as a basis of a mathematical model for poultry egg production (McNally, 1971). Having estimated a, b and c by regression analysis, the total lactation yield Y (kg) can then be calculated as

Data for the quantity of ammo acids consumed and their flow rates at the proximal duodenum for 33 diets fed to sheep have been statistically analysed by both univariate and multivariate methods. Analysis of variance of net loss (g/day) between mouth and duodenum of individual and total acida was not conclusive. Canonical variate analysis which takes regard of the correlations between different acids both within and between diets provided a conoise method of discriminating between diets. The advantage of this method in generating a unified account of digestion within the rumen is that it effectively reduces the problem from one of many dimensions to a situation where only the first few transformed variables need to be considered.

Black pigment is very frequently, but not invariably present in the mammary tissue of Large-Black, Berkshire and other dark-coloured sows. It is stated that the presence of this pigment (apart altogether from the question of the pigs being “on heat”) renders the bacon less saleable, owing to its discoloured or “seedy” appearance. If this is the case, it ought to be possible to remedy this fault, by breeding from individuals in which this pigment is absent, and so building up a strain of increased commercial value.

If on the other hand it be the case that the presence of black pigment is not in itself objectionable, but that the changes in the mammary area due to the occurrence of heat are what are not desired, the remedy is to be sought in spaying, a practice which must be carried out on a sufficient scale and be efficiently performed. That imperfect spaying (in which one, or a part of one, ovary is left behind, while the bed is wholly or partly removed) sometimes happens is shown by the facts described in this paper.

The expenses of the investigation described in this paper have been very largely defrayed by a grant made by the Development Commissioners through the Board of Agriculture and Fisheries.

The ability to detect and measure water stress accurately is critical for optimizing crop production. The Crop Water Stress Index (CWSI), the linear relationship of the difference between foliage and air temperatures as a function of the air vapour pressure deficit, is one widely used method. Under well-watered conditions, a ‘baseline’ is derived that is crop specific and presumed fairly constant, despite differences in development and physiology. This study reports changes in the baseline of the CWSI for lucerne crops not subjected to water shortage over 3 years. Studies of lucerne in California from April 1986 to October 1988 used the CWSI to plan irrigations. It was necessary to re-establish the baseline periodically throughout the experiment. In the first year it was similar to that reported in the literature, but in the second year it had a statistically significant steeper slope and higher intercept. In the third year, the regression equation was similar to that in the first year. The changes in the baseline are thought to be a result of crop age rather than year-to-year weather fluctuations. The baseline needs to be determined periodically as the crop matures, to ensure accurate interpretation of plant water stress.

In a study of two coarse-wool breeds (Awassi and Hamdani) the birthcoat and adult fleece were sampled from six body positions. Mean fibre diameter, mean fibre length, mean staple length and the percentages of fibre types were studied in relation to the birthcoat fibre type arrays.

The birthcoat of the two coarse wool breeds showed only plateau and saddle fibre type arrays. In Awassi lambs, plateau arrays were all P3 type whereas in Hamdani 28·6% of the plateau arrays were Po and the rest were P3 indicating a stronger base in the latter. S/P ratios, calculated from fibre types, were 2·22 and 2·27, at birth, and 3·56 and 2·93 at 4–8 weeks of age, in Awassi and Hamdani respectively. Awassi birthcoats showed more precipice within the CT group than those of Hamdani and plateau arrays were more endowed with the precipice than were saddle arrays.

A composite sample from the back and mid-side, in Awassi, and from the back and britch, in Hamdani, was found to be most representative of the birthcoat fibre types.

In the adult fleece of the Awassi breed, the mean fibre length following plateau arrays exceeded those following saddle arrays.

In Hamdani, the saddle arrays developed into coarser fibres in average diameter than those of plateau arrays whereas in Awassi no difference occurred. Awassi plateau arrays were followed by higher within-staple variability in distribution of fibre length than were saddle arrays, whereas in the distribution of fibre diameter there was no difference. In Hamdani, however, saddle arrays were followed by slightly higher within-stable variability in both length and diameter than were plateau arrays.

Birthcoat samples that had a transition in the CT group or had saddle array developed into adult fleeces with greater frequency of normal distribution in both fibre length and diameter, within staple. Adult fleeces that showed frequent bimodal distribution of both diameter and length, within staple, were those with birthcoats that had a precipice in length, or in coarseness and length, within their CT group or those with birthcoats that had plateau arrays.

1. The apparent cleanliness of the premises in which chicks are reared has little bearing on the growth rate of chicks within a given environment.

2. Bacterial counts of faeces from chicks reared under clean or extremely contaminated conditions showed no difference between the two sets of conditions.

3. Delaying feeding until 72 hr. after hatching retarded growth to at least 7 weeks of age. If the age of the chicks was calculated from the time at which the chicks were fed rather than the date of hatch, the weights of the chicks fed 72 hr. after hatching corresponded with those of the chicks fed immediately.

4. The contents of the duodenum and mesenteric intestine showed higher bacterial counts when feeding was delayed for 72 hr. than when feed was given shortly after hatching. This effect was no longer evident after the chicks were 1 week old.

5. Administration of penicillin in the water did not reduce the difference in growth rates between the chicks given feed immediately and those from which feed was withheld.

6. Antibiotics may decrease the thickness of the intestinal wall without stimulating growth.

1. Experiments were carried out in four seasons at Barberton, South Africa, occupying approximately 2¼ acres of ground. Three soil treatments were used, viz. Normal (N), Compressed (C) and Grubbed (loosened) (G).

2. Measures of consolidation of the soil were made with a specially designed apparatus, and large differences established (pp. 516–520).

3. Estimations of water content and nitrate content were carried out. No great differences were found (pp. 520–524).

4. Fortnightly samples of the plants were taken, from which numerical data were collected designed to estimate morphological development (primary data, pp. 526–529).

5. Derived data on net assimilation rate, relative leaf-growth rate and efficiency index were calculated (pp. 529–533).

6. Growth in total dry weight was found to conform approximately with an exponential law up to the time of flowering. Up to this stage also net assimilation rate was found to remain constant.

7. Growth differences between treatments were related to variation in net assimilation rate only (p. 531).

8. The results were analysed statistically. Significant results alone are emphasized.

9. In all respects growth and development on the consolidated soil was more rapid than that on the grubbed soil, normal being generally intermediate.

10. The results are discussed with reference to the question of nitrogen supply, water supply and aeration of the soil.

Fifteen cultivars of orchardgrass (Dactylis glomerata L.) were grown in the field at Hiroshima University, Japan, to investigate seasonal changes in leaf water relations and cell membrane stability (CMS) measured by the polyethylene glycol (PEG) test. Leaf water potential and osmotic potential were measured from August 1988 to August 1989. Solute concentration in leaf cell sap was also estimated.

Cell membrane stability increased, leaf water potential and osmotic potential decreased and turgor potential increased with decreasing environmental temperatures during autumn and winter. The significant increases observed in CMS may enable plants to tolerate freezing temperatures during winter. Decrease in leaf water potential may be a result of water-deficit effects due to soil freezing at low temperatures and the decrease in osmotic potential may help plants to maintain turgor and tolerate freezing conditions. Plants maintained higher turgor as the osmotic potential decreased to values as low as – 3·98 MPa during winter; the maintenance of turgor helps to maintain water uptake under water deficit conditions at low temperatures.

Sugar and K were the major osmotic contributors in orchardgrass leaves. Sugar and Ca concentrations increased and Mg and P concentrations decreased at cold temperatures. K concentration increased in six cultivars and decreased in nine others at cold temperatures. Sugar concentration in cell sap was negatively correlated with osmotic potential. It was concluded that seasonal changes in CMS may be mainly associated with the osmotic potential of the leaf tissues.

1. Four experiments in 1958 and five in 1959 compared responses to potassium (as combinedrilled muriate of potash) in the absence of nitrogen and in the presence of single and double doses of nitrogen (as broadcast sulphate of ammonia) on soils selected because they contained very little acid-soluble potassium.

2. Responses to 0·5 cwt. K2O/acre were obtained at six centres (two significant), but the effects of a further 0·5 cwt. K2O/acre were more variable and gains and losses (each at four centres) were almost equally balanced.

3. Gains from nitrogen were associated with previous cropping. N1 raised yields at seven centres (six significantly), but N2 raised yields further at only five centres (three significantly) and depressed yields significantly at three centres where barley followed a root crop or ley.

4. Potash did little to improve the strength of straw and therefore standing capacity in a wet season (1958) and had little effect upon the size of the grain, whereas nitrogen increased lodging and reduced the average size of the grain.

5. Increases in potassium uptake were associated with yield increases, whereas increases in nitrogen uptake were associated with both higher nitrogen percentage in grain and higher yields.

In a previous communication we have summarised the results obtained by us in a study of the nature and extent of atmospheric pollution in different parts of the city of Leeds and in further studies of some of the effects of smoke upon plant growth.