Effect of postnatal nutritional status on subsequent growth and reproductive performance of gilts

Two trials involving 128 gilts were conducted to determine the effect of nutritional status during the first 28 d postnatally on subsequent growth and reproductive performance. Nutritional status was altered by adjusting litter size at birth to either 6 or 12 pigs and maintaining a lactation length of either 13 or 28 d. Pigs weaned at d 13 were fed on an ad libitum basis or at 50% of ad libitum through d 28. After d 28, all pigs were fed the same diets through the first parity. By market weight (d 154) pigs recovered differences in body weight imposed during the early postnatal period. Postnatal nutritional status did not alter age at puberty. Gilts weaned at d 28 from litter size 6 produced 2.4 more (P less than .05) ova than gilts from litter size 12; however, when weaned at d 13, gilts from litter size 6 produced 2.3 fewer ova than gilts from litter size 12. Feed restriction for 15 d postweaning did not depress ovulation rate in gilts. Subsequent litter size was not affected by postnatal litter size, lactation length or feed restriction, even though growth rate and ovulation rate had been altered by treatments imposed during the first 28 d postnatally. Assuming no difference in fertilization, these data suggest that prenatal mortality was altered by the early postnatal treatments and was the limiting factor for litter size. Until factors that influence prenatal losses are characterized and controlled, the alteration of nutritional status by changes in postnatal litter size, lactation length or feeding level will not detrimentally affect subsequent litter size in gilts.     

Etiology of ammoniated hay toxicosis

Some animals consuming hay treated with anhydrous ammonia have developed neurological signs including hyperexcitability, circling and convulsions. A series of experiments was conducted to identify tentatively the toxin and determine its mode of action. Three out of four sheep fed ammoniated orchardgrass hay (approximately 4% ammonia on a dry basis) developed convulsions. Two of the three sheep died within 18 h of the onset of signs. The concentrations of blood lactate and pyruvate were elevated in the symptomatic sheep (P less than .05). A proposed toxin, 4-methyl imidazole, did not induce the syndrome when 750 mg/d (approximately 10 times the dietary amount) were administered orally. Four out of five calves that received milk from cows fed ammoniated oat hay (approximately 5% ammonia on dry basis) displayed hyperexcitability and circling. Concentrations of blood lactate and pyruvate were also elevated in the calves. The crude alkaloid fraction of the toxic milk produced neurological signs similar to those of the calves when injected into mice. A fluorescent compound was found in the alkaloid fraction of toxic milk and ammoniated hay, but not in control milk or untreated hay. The fluorescent compound was quite labile; hence, characterization has been unsuccessful thus far.     

Untersuchungen zur Nutzbarkeit des generativen Speicherpotentials von indeterminierten Ackerbohnengenotypen (Vicia faba L.)

Investigations on the utilization of the generative storage potential of indeterminated field bean genotypes ( Vicia faba L.)
The gradation in seed yield between and within the inflorescences of a field bean plant results from a hierarchical control by way of internal competition in connection with hormonal regulation. Following this hypothesis in genotypes with different yielding capacity (2 inbred lines, 1 hybrid) the two proximal flowers/inflorescence of the nodes 3–6 (counted from the bottom of the plant) were either removed or treated with growth regulators. AMO-1618 was applied for inhibition of the gibberellic acid biosynthesis, or chlorflurenolmethylester (CFM) for reduction of indole-3yl acetic acid translocation as both phytohormones might be concerned with the hierarchical control of the storage system. — Independent from yield level a reduction of the used storage potential in control plants up to 50% by treatments was fully compensated for in other regions and positions of the plant. AMO-1618 application in some cases indicated an increased seed yield/plant, whereas CFM only increased the number of sterile pods/plant. These effects are discussed in relation to the storing efficiency and to yield stability of an indeterminated faba bean plant.     

Genetic variation among American seed sources of Ailanthus altissima (Mill.) Swingle

Variability among and within seed sources of naturalized Ailanthus altissima (Mill.) Swingle in seed and height growth characteristics indicated that significant differences exist both at the seed source and between individual trees. Genetic variance was distributed in an approx. 1 : 2 ratio among seed sources and individual mother trees respectively. Results of the study suggest that artificial selection of ailanthus for breeding purposes would be most efficient if primary selection were directed toward individual trees.     

Comparison of the effects of infection with Trichostrongylus colubriformis, T. vitrinus and T. rugatus in merino lambs

Groups of six worm-free merino lambs were infected with 100,000 larvae of T. colubriformis, T. vitrinus, T. rugatus or a mixture of the three species and were slaughtered 21 days later. Nematodes were distributed predominantly in the first 3 m of the small intestine where they caused subtotal villus atrophy. T. vitrinus caused severe erosion of the epithelium; erosion was less severe with T. colubriformis infections and mild with T. rugatus infections. Plasma concentrations of albumin declined during the experiment and were most marked in sheep infected with T. vitrinus. Plasma phosphate concentrations declined during infection with all three species, while plasma concentrations of globulin and calcium declined only in sheep infected with T. vitrinus. Food intake was reduced in all groups, but was most marked with sheep infected with T. vitrinus. T. vitrinus appeared to be more pathogenic than the other species.     

Cross-resistance to pyrethroids and other insecticides in Aedes aegypti

Two substrains of Aedes aegypti, already resistant to DDT and pyrethroids, were further selected using either DDT or permethrin by mass exposure of the females only. DDT selection over 14 generations raised the resistance to DDT so far that no accurate LC₅₀ values could be determined. Selection with permethrin raised the tolerance to an irregular plateau 7–10 times the original. DDT selection in the adults raised the DDT resistance of the larvae, but this could be partly overcome using a dehydrochlorinase inhibitor. The resistance to pyrethroids was increased but tolerance of dieldrin, malathion and propoxur compounds was little changed. Permethrin selection of the adults raised resistance to pyrethroids more than DDT selection but also increased DDT resistance. Similar patterns were found for the larval insects. A strain from Demerara in Guyana showed both DDT and pyrethroid resistance, including strong resistance to pyrethrins together with dieldrin and propoxur. It was concluded that two major independent resistance mechanisms existed in the selected strains, a dehydrochlorinase affecting DDT alone, and an unknown mechanism, probably nerve insensitivity (kdr) affecting both DDT and pyrethroids.     

The growth of swine bone marrow cells in the presence of heterologous colony stimulating factor: Characterization of the developing cell population

Conditioned medium prepared from the mouse fibroblast cell line L 929 which is known to produce colony-stimulating factor active on mouse bone marrow cells was also able to stimulate the growth of swine bone marrow cells in a liquid culture system. During the first 4 days of culture mononuclear phagocyte and granulocyte colonies developed. Prolonged cultured cells were classified belonging to the macrophage lineage by morphological and cytochemical criteria. These cells fulfill also functional characteristics for macrophages, like expression of Fc receptors, immune phagocytosis and production of prostaglandins. These bone marrow-derived macrophages could also be activated with LPS and lymphocyte-derived mediators.     

Eradication of over-wintering mildew (Podosphaera leucotricha) in apple buds by nitrogen-containing surfactants

The eradicant activities of 24 nitrogen-containing preparations, comprising primary, secondary or tertiary amines, amine acetates, diamines, amine oxides or quaternary ammonium salts, were assessed in trials with potted dormant apple rootstocks, heavily infected with the powdery mildew fungus Podosphaera leucotricha. The surfactants consisted of mixtures in which C₁₂/C₁₄ or C₁₆/C₁₈ alkyl or alkenyl compounds predominated. Of the amine acetates (at 50g litre^?1), only the formulation containing C₁₂/C₁₄ primary amine acctates was considered worthy of further evaluation. Some amine oxides and quaternary ammonium compounds (at 35 g litre^?1) were good eradicants and were as effective as ‘PP222’ a (nonylphenol-ethoxylate mixture) which was included for comparison. All the compounds showing good activity contained one C₁₂/C₁₄ alkyl group whereas C₁₆/C₁₈ compounds, whether saturated or unsaturated, were relatively inactive. In a field trial, C₁₂/C₁₄ (dimethyl) amine oxide, C₁₂/C₁₄bis (2-hydroxyethyl) amine oxide, and C₁₂/C₁₄ amine acetate (35 g litre^?1) greatly reduced the amount of primary mildew on trees that were previously heavily infected, but there were signs that the fruit yield was reduced.     

Cockroach control in sewers in Singapore using bioresmethrin and piperonyl butoxide as a thermal fog

Cockroaches have considerable importance as vectors of disease. In tropical areas, large populations of Periplaneta americana may be found in sewers and the refuse chutes of large apartment blocks. These cockroach populations are not accessible to residual insecticide treatment with sprays but may be controlled with thermal fogs of pyrethroids. An experiment on the use of bioresmethrin (5-benzyI-3-furyimethyl-(+)-trans chrysanthemate) as 0.15% and 0.25% w/v solutions with equal amounts of synergist in kerosene discharged from a TIFA fog generator was made at Toa Payoh in Singapore. Effective control was obtained with 0.15% bioresmethrin plus 0.55% piperonyl butoxide in kerosene blown into the sewers and waste chutes initially, at four weeks, at eight weeks later and then followed by treatment every two months.