L‐aspartic acid and urea supplementation of low‐protein layer diets1

1. Urea supplementation of low‐protein (125 g/kg) conventional‐type diets for layers, whether containing fish meal or not, did not appear advantageous.

2. Supplementation of the low‐protein diet with aspartic acid did not affect egg production rate or efficiency.

3. Soyabean meal supplementation of the low‐protein diet increased egg weight significantly whereas aspartic acid did not.     

Factors affecting the variability in cracked and dirty eggs and egg production profitability on an integrated poultry operation

1. A number of factors causing variability in the percentages of cracked, and dirty eggs and weekly standard margin (WSM) of returns from eggs over production costs were examined on an integrated commercial poultry plant in Scotland.

2. As the bird aged, the percentage of cracked eggs increased (P <0.01) and the percentage of grade A eggs and WSM decreased (P <0.01). Cracks in dirty eggs (10.1%) were more than double those in all eggs laid (4.9%).

3. Seasonal effects on percentage cracked eggs and percentage grade A eggs were one‐third the magnitude of those due to age but were significant (P <0.05).

4. Variability in percentage cracked eggs, dirty eggs and WSM accounted for by the factors measured, were 72, 64 and 92% respectively.

5. The variability in WSM was significantly affected by percentage lay, food consumption and age but not by percentage cracked eggs, originally dirty and grade A eggs.

6. Flock management and climate inside the laying house each increased the amount of variability accounted for in the percentage cracked eggs and dirty eggs by at least 10%.     

On estimating non‐additive genetic parameters in chickens 1

1. Several economically important traits in two Leghorn populations (over 9000 birds) were examined for additive and non‐additive components of genetic variance and sex‐linked effects. Data were analysed by two different statistical models based on least‐squares procedures.

2. Six different covariances were first calculated between relatives; i.e., full‐sibs, 3/4‐sisters, half‐sisters, dam‐daughters, grandam‐granddaughters and aunt‐nieces.

3. From the covariances, weighted least‐squares equations were used to obtain estimates of variance components for additive genetic, dominance, maternal and sex‐linkage effects.

4. The estimates of non‐additive components were highly variable but generally small compared with the additive genetic estimates.

5. In general this study suggests that for most traits, with the possible exception of rate of egg production, there is relatively little non‐additive genetic variation.

6. The consequences of possible negative correlations between additive effects and maternal effects are considered as they might apply to egg production in poultry.     

Broiler growth and feeding behaviour in three different lighting regimes

1. Female broiler chicks reared in a 12‐h photoperiod which included a simulated “dawn” and “dusk” grew slightly faster than those reared in a 12‐h photoperiod of uniform light and others kept in continuous light.

2. This was apparently because the chicks subjected to dawn and dusk ate more food than those subjected to 12‐h uniform light and converted food more efficiently than those in continuous light.     

Ultrastructural changes in leaf and needle segments treated with herbicides containing picloram

The herbicide Tordon 50D (picloram+2,4-D) affected the integrity of the nucleus and cell membranes in Pinus radiata needle segments and caused the swelling of internal chloro plast membranes and the eventual disintegration of the chloroplasts. Tordon 22K (picloram) only affected chloro plast structure. Both herbicides had similar adverse effects on cell membranes and chloroplasts of Eucalyptus viminalis.     

The effect of soil aggregate size and water content on herbicide concentration in soil water

Suspensions of wettable powders of metribuzin and simazine were sprayed onto samples of two soils of two particle size grades, > 2.5 mm and <0.5 mm. The soils were either air-dry or at a water content of 12%. After either 1 h or 1 week, water was added to give a soil to water ratio of 1:1. Samples of solution were analysed after 1, 24 and 48 h. With metribuzin the intial concentration for both soils after wetting was greater from the >2.5 mm samples than the <0.5 mm samples, following application to dry soil, but by 48 h the differences were negligible. With simazine WRO soil did not show this effect at all and with Kirton soil only small differences were seen. If the soil was wet at the time of application, particle size had no effect except with simazine in Kirton soil. Generally metribuzin concentrations were higher after application to wet than to dry soils for at least 24 h after wetting whereas simazine concentrations were higher from initially dry soils and the differences had virtually disappeared 24 h after wetting. With the WRO soil herbicide concentrations in soil water were higher if the soil was wetted 1 h after spraying than if left for 1 week but the differences rarely persisted for 48 h. No such trend was observed with Kirton soil. It is concluded that the differences observed in these experiments could be responsible for variations in the performance of soil-applied herbicides.     

The selectivity of methabenzthiazuron between barley, perennial ryegrass and Poa trivialis

In field experiments methabenzthiazuron at 1.1 kg ai/ha applied pre-emergence gave good control of Poa trivialis L. in perennial ryegrass S23 which was undersown in spring barley (Zephyr); no significant damage to barley or perennial ryegrass resulted from 2.2 kg ai/ha. However this dose applied when barley had three to four leaves decreased the subsequent barley yield. In pot experiments in the glasshouse methabenzthiazuron was active mainly due to uptake through the soil. Much greater damage to barley and perennial ryegrass resulted when herbicide-treated soil was placed below seed level than above the seed. The difference was less marked with P. trivialis. The latter started to develop secondary roots near the soil surface earlier than either perennial ryegrass or spring barley.     

Persistence and movement of ethofumesate in soil*

Persistence of ethofumesate [(±)2-ethoxy-2.3-dihydro-3,3-dimethylbenzofuran-5-yl-methansulphonate] in soil was associated with soil temperature. Ethofumesate applied at 4.5 kg/ha in November persisted about twice as long in soil as that applied the following March. In another field study, 88–91% of the herbicide had dissipated after 24 weeks in sandy loam soil, compared to 72–77% in loam soil when it was applied at rates of 2.2, 3.4, 4.5, and 9.0 kg/ha. The rate of degradation was independent of the initial rate of chemical applied. The time required for 50% of the herbicide to dissipate in sandy loam and loam soils was 7.7 and 12.6 weeks, respectively. The movement of ethofumesate in these two soils over a 24-weeks sampling period was confined mainly to the upper 7.5 cm of the soil profile.     

Endocrine and sperminogenic testicular function. 8. Relationships between testicular and plasma testosterone concentrations as well as between the number of Leydig cells in testicular tissue and their cell nucleus volume in boars of different ages]

Testicular tissue and blood samples (V. spermatica interna) were taken from 32 boars during castration. The animals were different age groups. Against this background, studies were conducted into the correlations between testicular and plasma testosterone, on the one hand, and the amount of interstitial cells of Leydig in testicular tissue as well as the latters' cell nuclei volumes, on the other. The results seemed to support the conclusion that any age-dependent increase of testicular and plasma testosterone concentrations was caused unambigously by an absolute increase in volume of androgenic testicular tissue, in concomitance with testicular growth, in other words, by rise in the total number of interstitial cells of Leydig.     

Structure-activity relationships of 1,2,3-benzothiadiazoles as synergists for carbaryl against the house fly (Musca domestica)

Fifty six 1,2,3-benzothiadiazoles and related compounds were evaluated as carbaryl synergists against the house fly (Musca domestica). Many of these were excellent synergists, the most active being those containing various combinations of halogen, alkyl, or alkoxy substituents in the 5- and/or 6-positions of the ring.Regression analysis on the data from 14 compounds for which substituents constants were available established that synergistic activity can be satisfactorily described by equations in terms of the hydrophobic bonding constant (π) and the homolytic free radical constant (σ ·).The results with compounds related to the 1,2,3-benzothiadiazoles suggest that synergistic activity is associated primarily with the diazosulfide moiety.