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PubMed2026

Antimicrobial Resistance Phenotypes and Genotypes of Cecal Digesta Escherichia coli of Pullets Fed Omega-3 Fatty Acids or Yeast Bioactives (Glycobolites).

Antimicrobial resistance (AMR) is a significant threat to poultry production and food safety. In laying hens, commensal Escherichia coli can serve as a reservoir of AMR and virulence genes. Although omega-3 fatty acids (N-3 FAs), yeast bioactives (YB), and spacing allowance (SA) influence gut health and immunity, their combined effects on AMR profiles of gut bacteria remain unclear. A total of 2,832 chicks were raised in enriched cages under high (HSA, 348&#xa0;cm2/bird) or low (LSA, 284&#xa0;cm2/bird) SA and fed a control diet (C), C+3% N-3 FA, or C+0.05% YB. At 4, 16, and 35&#xa0;weeks of age (woa), cecal contents were cultured on ChromoCult agar to isolate E. coli. Susceptibilities of isolates to 14 antibiotics were determined. Of the 428 isolates, 35.7% were resistant to at least one antimicrobial, and overall, AMR prevalence decreased with age (P&#xa0;<&#xa0;0.05). At each of 4 and 16 woa, N-3 FA-fed birds showed the lowest prevalance of ampicillin-resistant (P&#xa0;<&#xa0;0.05). The prevalence of streptomycin resistance was higher in N-3 FA than in YB-fed birds at 16 woa (P&#xa0;=&#xa0;0.02) but lower than in control-fed birds. Whole-genome sequencing and analysis of 237 selected isolates identified 19 antimicrobial resistance genes (ARGs) and 29 plasmids, with the distribution of 15 (78.9%) ARGs and 19 (65.5%) plasmid replicons affected by either diet, SA, or age (P&#xa0;<&#xa0;0.05). Several virulence genes were identified in sequenced E. coli isolates, with the prevalence of those encoding fimbriae, pili, protectin, and toxins being higher in younger pullets (P&#xa0;<&#xa0;0.05). Overall, isolates of phylogroups A and B1 were predominant; however, at 4 woa, phylogroup D isolates were most prevalent, depending on diet and SA (P&#xa0;<&#xa0;0.05). Isolates of serotype O23:H16, ST2 were the most prevalent. Of the 237 sequenced isolates, 13 were related to human extraintestinal pathogenic Escherichia coli (ExPEC) strains. Overall, these findings suggest that N-3 FA YB and SA modulate AMR and virulence genotypes of E. coli in laying hens, highlighting their potential use of these agents in mitigating AMR.

Antimicrobial resistance↗
PubMed1976

The effects of estradiol administration of the hepatic activities of some enzymes of carbohydrate, amino acid and lipid metabolism in the immature pullet.

Two experiments were performed to examine the effects of intramuscular estradiol administration on the hepatic specific activities of some enzymes of lipid, carbohydrate and amino acid metabolism in the immature fowl. Estradiol increased the specific activities of the hepatic lipogenic enzymes, ATP citrate lyase and malate dehydrogenase (decarboxylating) (NADP), but had no effects on the activities of the glycolytic, gluconeogenic and amino acid metabolising enzymes except for pyruvate kinase and glutamate dehydrogenase which were reduced in activity in both experiments. The results indicate that the estrogen-induced increase in hepatic lipid biosynthesis is due to a specific effect on lipid metabolism and not to a general increase in liver metabolism.

ATP Citrate (pro-S)-Lyase↗
PubMed1975

A genetic analysis of adult mortality in Leghorn by heavy-breed reciprocal crosses.

1. Genetic mechanisms of resistance to disease in 1930 pullets and 296 cockerels were investigated by using a Leghorn line (G), a heavy-breed line (H), and their reciprocal crosses G x H and H x G plus two synthetic lines, GnH and HnG which were segregating for line-intact Z chromosomes. 2. The most frequent cause of death was leukosis. 3. Gmale x Hfemale pullets had a significantly higher adult mortality (40-9%) than the reciprocal cross (27-3%). 4. A direct effect of the Z sex chromosome on the incidence of leukosis or on total adult mortality could not be demonstrated. 5. Maternal breed effects and heterosis were relatively more important than Z sex chromosome and autosomal breed effects as causes of both leukosis and total laying house mortality. 6. The heavy-breed line had higher cellular resistance to the leukosis/sarcoma virus subgroups A and B than did the Leghorn line.

Animals↗
PubMed1975

Immune response and the B blood group locus in chickens.

Chickens of three blood group genotypes, B1B1, B1B2 and B1B19, were compared in their ability to produce antibodies. The B locus is the major histocompatibility locus in this species. Homozygous B1 pullets had significantly higher adult mortality than did the B1 heterozygotes. In two separate experiments the B1B1 females produced significantly fewer antibodies to Salmonella pullorum than did the B1 heterozygotes. Also the B1B1 pullets responded with lower antibody titers following immunization with ferritin, bovine serum albumin and parainfluenza-3 virus, although the differences were not significant. The results of this study suggest that an immune response gene is associated with the major histocompatibility locus in chickens, paralleling the H-2 locus and Ir genes in mice.

Alleles↗
PubMed1975

Effect of regression of Rous sarcoma tumors upon egg production in an inbred line of White Leghorns.

Reserach was conducted to determine whether development and subsequent regression of a Rous sarcoma virus (RSV) induced wing-web tumor influenced egg production. Fifty-seven six-week old pullet chicks of inbred line 6 of the United States Department of Agriculture, Regional Poultry Research Laboratory, East Lansing, Michigan, were inoculated subcutaneously in the left wing-web with 0.1 ml. of a 10-minus 3 dilution of a pseudotype of Bryan high titer RSV designated BH-RSV (RAV-1). Thirty chicks were left uninoculated. Each chick was examined for tumor growth at regular intervals to 10 weeks post-inoculation. A tumor was considered regressed if it disappeared completely. Ninteen regressor and 22 uninoculated females were placed in laying cages at 4.5 months of age and egg production data obtained over seven 28-day periods. The difference in hen-day egg production between regressors and uninoculated controls favored regressors by 2.7 eggs/bird and was statistically significant. Physiological stimulus from cellular immunity, linkage and pleiotropy are discussed as possible caused of the higher egg production in regressors.

Animals↗
PubMed1978

Vaccination against infectious bronchitis and the immunosuppressive effects of infectious bursal disease.

An immunosuppressive effect was demonstrated in chickens which were infected with infectious bursal disease virus (IBDV) early in life and prior to or shortly after vaccination with infectious bronchitis virus (IBV). This effect was evident by an increased susceptibility to respiratory tract infection with IBV and reduced virus-serum neutralizing antibody levels. Chickens which were hatched from dams susceptible to infectious bursal disease (IBD) were less responsive to IBV immunization attempts, if exposed to IBDV, than were those individuals hatched from IBD immune dams. However, in some cases, chickens from IBD immune dams were also more susceptible to IBV challenge when they had been exposed to IBDV and when compared to birds unexposed to IBDV but vaccinated against IB. An effect of cyclophosphamide on the bursa of Fabricius also had an immunosuppressive action on IBV immunity which was similar to the results from IBDV exposure. The data engendered from these trials may explain the unsatisfactory immunity sometimes observed under field conditions when broilers and replacement pullets are vaccinated at an early age.

Animals↗
PubMed1975

Lack of feedback regulation of cyclic 3':5'-AMP accumulation by free fatty acids in chicken fat cells.

Fat cells isolated from the mesenteric adipose tissue of chickens (pullets) responded to glucagon with an increase in lipolysis and a sustained rise in cyclic adenosine 3':5'-monophosphate (cyclic AMP) over a 30-min incubation. The prolonged accumulation of cyclic AMP due to glucagon in chicken fat cells was primarily intracellular. In addition, there was little increase in cyclic AMP accumulation due to theophylline alone or potentiation of the increase due to glucagon. These data indicate that chicken fat cells, unlike rat fat cells, are relatively insensitive to theophylline. Neither lipolysis nor cyclic AMP accumulation by chicken fat cells was inhibited by free fatty acid to albumin ratios (3 to 7) which markedly reduced both events in rat fat cells. However, in the absence of albumin from the medium, lipolysis in chicken fat cells was reduced, but not to the same extent as in rat fat cells. Chicken fat cells did accumulate more intracellular free fatty acids in response to lipolytic agents than did rat fat cells. The uptake of oleate by rat and chicken fat cells was identical. Glucagon-induced accumulation of cyclic AMP by chicken fat cell ghosts was unaffected by added oleate. Under identical conditions glucagon-induced adenylate cyclase activity of rat fat cell ghosts was markedly inhibited by added oleate. Triglyceride lipase activity of the pH 5.2 precipitate from a 40,000 x g infranatant of homogenized fat cells from chickens was less sensitive than that from rat fat cells to the ratio of oleate to albumin. These results suggest that the maintenance of cyclic AMP levels in chicken fat cells incubated with lipolytic agents results from the relative insensitivity of chicken fat cells to free fatty acid inhibition of cyclic AMP accumulation.

Adenosine Deaminase↗
PubMed1976

[Marek's disease--characterization of the VUB-70 strain in vivo].

In the course of serial passaging of the strain of Marek's disease (MD) (VUB-70) in White Leghorns the author investigated the morbidity, mortality, development of the MD-specific changes, and the effect of sex on these indices, for the purpose of characterization of the biological properties of an isolated strain of MD in vivo. The incubation period lasted from 41 to 46 days p. inf. on the first day of life. Pullets showed greater sensitiveness towards infection not only through higher morbidity and mortality, but also due to a larger number of tumorous changes. In MD-positive animals the same proportion of macroscopic and microscopic changes was found. The average occurrence of Marek's disease amounted to 74.4 p. c. On the basis of the biological properties in vivo the VUB-70 strain was characterized as a medium pathogenic strain of the acute form of Marek's disease.

Acute Disease↗
PubMedDate not supplied

[The influence of infectious bronchitis virus on egg production, fertility, hatchability and mortality rate in chickens (author's transl)].

In 35 flocks comprising almost 100,000 White Plymouth Rock birds producing hatching eggs, infectious bronchitis (IB) caused a decline in production which appeared to be connected with the age of the birds, when the outbreak started (table I). In outbreaks of IB in pullets 3-4 weeks before they are ready to lay there is a considerable risk of delay of production and a generally too low yield (fig 1). Egg laying birds, 25-34 weeks of age, suffered a drop in production from 20-80% (on an average 40%) and normal yield was never regained. After 6-8 weeks the production rate usually stabilizes around 6-12% below normal production. IB outbreaks in the middle of the production period (35-45 weeks) resulted in a decline of egg production of 40-90% (on an average 55%). Recovery of production usually occurred after 6-8 weeks (fig. 2). Observations of clinically typical outbreaks without any laboratory verification indicate that IB outbreaks at the end of the egg production period resulted in irreparable decline of production. Marked alterations in exterior and interior quality of the egg have been observed. Both mishapen appearance, rough and thin shell, bleached shell color and watery albumen have occurred. These facts did sometimes cause transient increased "sorting out" of haching eggs. Also fertility rate was noticed to be affected temporarily during and after an attack of IB. In 17 flocks drops of 1.7-22.4% (on an average 7.4%) were registered (fig. 3). Also hatchability decreased 3.0-43.8% (on an average 13.7%) (fig. 4). In most of the registered outbreaks of IB the weekly mortality remained below 1%, but in single cases the figure could rise up to about 4% (fig. 5), most often in flocks where complicating factors such as secondary infections caused by E. coli or M. gallisepticum were present.

Animals↗
PubMedDate not supplied

Interaction of infectious bursal disease and coccidiosis in layer replacement chickens.

During a floor-pen study on anticoccidial programs for layer-replacement pullets, there was a natural outbreak of infectious bursal disease (IBD). The interaction of coccidiosis and IBD was characterized by: excessive deaths from coccidiosis; and apparent failure of some anticoccidial drug treatments. Immunity to coccidiosis was not blocked by the IBD infection, although immunity was less in some treatments than would be expected with the degree of coccidiosis exposure.

Animals↗
PubMed1975

[Bacteriological and physicochemical studies of the meat from poultry with acute Marek's disease].

Studied were bacteriologically a total of 114 birds affected with acute Marek's disease (40 broilers, 44 growing layers, and 30 adult layers) as well as 100 healthy control birds of the same three categories. A chemical analysis was performed of the red and white meat of 20 of the diseased pullets and 20 of the diseased adult layers as well as of 34 of the affected broilers. The investigation included the same numbers of the control birds. Extractions of the sampled meat were studied in terms of catalase number, pH value, and peroxydase activity. It was found that enterobacteria in the viscera of the diseased birds were three to nine times more frequently encountered than in the same organs of the controls. In two cases Salmonella bacteria were also isolated from the affected chickens. In three cases there were enterobacteria in the red musculature of these birds. The meat of the diseased birds had higher water content, higher catalase number and pH value, with lower contents of proteins, fats, and mineral matter. The only exception was the red meat of these birds which had higher content of crude protein as compared with the red meat of the normal birds.

Acute Disease↗