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Biomedical subjects

D J Farrell

Publications and source records attributed to D J Farrell.

At least 91 records · Page 5Linked to original sources
PubMed1984

The effect of food restriction during rearing on fasting heat production of layer strain pullets and hens.

Fasting heat production was measured in darkened respiration chambers at three chronological and three physiological ages during rearing and laying in a layer strain to determine the effects of food restriction during rearing. There were three rearing treatments (42 to 162 days of age) in which birds were allowed ad libitum food intake (F) or were restricted by time (TR), in which birds were allowed continuous ad libitum food intake for about 24 hr in every 72 hr, or by proportion (PR), in which birds were offered each day 60 to 70% of the quantity consumed by F birds the previous day. Liveweight at 163 days of age was reduced by 19 and 15% for TR and PR birds, respectively, compared to F birds. Ad libitum food consumption was allowed during the laying period. Chronological age measurements were carried out at 140 days of age (prelay), 332 days of age, and 370 days of age. Physiological age measurements were carried out at sexual maturity (first egg), peak production (28 days after first egg) and postpeak production (98 days after first egg). Fasting heat production, measured under conditions that minimized physical activity, was not altered after correction for liveweight changes by the food restriction treatments. Based on this and other published studies, it was postulated that physical activity may play an important role in determining the effects of food restriction in poultry.

Animals↗
PubMed1983

Energy metabolism of groups of broiler breeders in open-circuit respiration chambers.

Energy metabolism of broiler breeders housed in groups was measured in large open-circuit respiration chambers. The design, function and calibration of the chambers are described. Each of the three chambers has a capacity for 24 pullets or adult layers, or 16 adult broiler breeders. Control of ventilation rate is by calibrated choked-flow nozzles. Before experiments were started the system was assessed by CO2 infusion and recovery and ethanol combustion studies. Percentage CO2 recoveries were greater than 98 of infused and the mean (+/- SD) quotient of CO2 produced to O2 consumed from the combusion of ethanol was 0.67 (+/- 0.02). Forty-eight broiler breeder hens in lay were placed in the respiration chambers (16 per chamber) and fed at different rates from around maintenance to about twice this value. The energy required for maintenance (MEm) was 365 kJ/kgW0.75 d and the efficiency of utilisation of metabolisable energy (ME) for production (kp) was 0.70. Starvation heat production was about 350 kJ/kgW0.75 d and was shown to affect the derived values of the energetic parameters when included in the relationship between retained energy and metabolisable energy intake. Published results were recalculated and found to support this.

Air↗
PubMed1982

Calorimetric measurements of the energy and nitrogen metabolism of Japanese quail.

1. Respiration calorimetry measurements were made over 4 d on normally-fed groups of 10 male or 10 female quail during three periods commencing at 12, 19 and 26 d of age. Carcass compositions were determined on groups of birds of each sex at 2 and 5 weeks of age. 2. Expressed per unit body weight, food and metabolisable energy (ME) intake and weight gain decreased between 2 and 3 weeks of age, but remained constant thereafter. 3. No differences were observed between sexes for any variable measured. Efficiency of utilisation of ME for energy retention was only 0.33. This was mainly because the majority of energy was retained as protein tissue. 4. Nitrogen (N) retention (g/d) increased with increasing dietary N intake but when expressed as a proportion of N intake, declined from 0.46 at 2 weeks to 0.33 at 4 weeks. Fat retention increased substantially during week 4. 5. Carcass analyses showed that fat, protein and ash were higher for quail at 5 weeks than at 2 weeks of age. At 5 weeks carcass fat was only 60 g/ kg.

Animals↗
PubMed1981

Availability to pigs of amino acids in cereal grains. 1. Endogenous levels of amino acids in ileal digesta and faeces of pigs given cereal diets.

1. Endogenous levels of amino acids in ileal digesta were determined as the output from pigs given protein-free diets and by extrapolation to zero intake of linear regressions of ileal amino acid output v. dietary amino acid intake. The protein-free diets included 0 or 50 g cellulose/kg and extrapolations were made from two series of four diets which contained graded levels of wheat or barley as the only source of protein. Within each series, dietary fibre level (mg/g) was maintained at approximately 140 or 190 neutral-detergent fibre (NDF) respectively. Endogenous amino acid levels in faeces were also determined. 2. Endogenous amino acid output in faeces was linearly related to dietary fibre level; endogenous ileal output increased with dietary fibre up to approximately 100 mg NDF/g, after which endogenous output no longer increased. 3. The amino acid composition of endogenous ileal protein varied little among levels of output and among different experiments. The composition appears to be determined by the predominance of mucin protein, the slow absorption of some acids and the methods commonly used to measure output. The very high levels of proline and glycine in ileal digesta seemed characteristic only of protein-free and low-protein diets. 4. The amino acid composition of endogenous faecal protein also varied little among different estimates, but was considerably different from that of endogenous ileal protein. Furthermore, the similarity of bacterial and faecal proteins suggested that much of the endogenous faecal protein was of bacterial origin.

Amino Acids↗
PubMed1981

Availability to pigs of amino acids in cereal grains. 2. Apparent and true ileal availability.

1. Pigs prepared with re-entrant ileal cannulas were used to determine the ileal availability of amino acids in nine cereal grains including five wheats, sorghum (Sorghum vulgare Pers.), maize, barley and Triticale. 2. The average true availability of amino acids in these grains was 0.88 but there were consistent differences in availability among amino acids. Generally, lysine and threonine were among the least available amino acids while glutamic acid and arginine were among the most available amino acids in cereal protein. 3. There was much variation in amino acid availability within a grain species (wheat) as among the other grains.

Amino Acids↗
PubMed1981

Availability to pigs of amino acids in cereal grains. 3. A comparison of ileal availability values with faecal, chemical and enzymic estimates.

1. Availability values for amino acids in nine cereal grains determined by faecal analyses with pigs and by the Silcock available lysine test (Roach et al. 1967) and an in vitro digestibility assay were compared with ileal availability values for the same grains determined with pigs by Taverner et al. (1981 b). 2. There was a significant canonical correlation of ileal and faecal availability values. On average, apparent faecal availability of the indispensable amino acids was 4.2% greater than apparent ileal availability, but the difference was up to 12.6% for threonine. Furthermore, the difference appeared to increase as the digestibility of the grain decreased. 3. Silcock available-lysine values for the cereal grains were unrelated to the lysine truly absorbed by the pig. 4. There were close relationships of ileal protein and lysine availability values of nitrogen digestibility determined by an in vitro assay using pronase enzyme.

Amino Acids↗
PubMed1981

Availability to pigs of amino acids in cereal grains. 4. Factors influencing the availability of amino acids and energy in grains.

1. Protein digestibility and lysine availability were determined in a range of grain samples using an in vivo digestibility assay calibrated with ileal digestibility values. 2. Mean (+/- SE) values predicted for nitrogen digestibility were 0.92 +/- 0.011 in wheat and 0.88 +/- 0.021 in barely, and the predicted lysine availability in wheat was 0.86 +/- 0.021. 3. Chemical and physical characteristics of the grains were determined and those most closely associated with protein digestibility for wheat were the contents of hemicellulose, neutral-detergent fibre, the bulk density, and to a lesser extent, N and acid-detergent fibre content. These relationships were used to determine prediction equations for the availability lysine content of wheat.

Amino Acids↗
PubMed1980

A comparison of the energy and nitrogen metabolism of starved ducklings and chickens.

1. Respiration chambers were used to measure, over 24 h, the heat production of groups of starved ducklings from two batches and of starved broiler chickens from one batch up to 28 and 39 d of age, respectively. Duration of starvation prior to measurements and ambient temperature were adjusted according to the age of the birds. 2. Respiratory quotient of 0.705 for chickens was significantly lower than that of 0.713 for ducklings. 3. Starvation heat production (kJ/d) of ducklings was 804 kgW0-70 compared with 675 kgW0-74 for chickens. There were differences in heat production between the two batches of ducklings used when expressed per kg body weight (W). 4. Ducklings lost more body weight, body fat and protein than chickens during starvation. Gaseous ammonia-N was on average 9% of N excreted by ducklings and 4% of N excreted by chickens.

Animals↗
PubMed1980

A comparison of the energy and nitrogen metabolism of fed ducklings and chickens.

1. Energy measurements were made over 4 d on groups of three ducklings (aged from 5 to 22 d), and three broiler chickens (aged from 11 to 32 d) offered high- or low-energy diets. 2. Food, metabolisable energy (ME) and water intakes were significantly higher for ducklings than for chickens. The ratio of water:food was 4-2:1 and 2-3:1 for ducklings and chickens, respectively. The food conversion ratio differed between diets but not species. Performance was generally better for both species on the high-energy diet. 3. Heat production, energy, fat and protein retentions were higher for ducklings than chickens, and ducklings retained 0.44 of their energy as fat compared with 0.37 for chickens. Overall the ratio of protein (g) to fat (g) retention was 2.2:1 and 2.8:1 for ducklings and chickens respectively. 4. For ducklings, metabolisability of the high-energy diet declined from 0.774 to 0.747, and to a lesser extent of the low-energy diet, as they aged. There was no such decline for chickens. Net efficiency of utilisation of ME for gain was 0.64 for ducklings compared with 0.50 for chickens. 5. Fractional retention of dietary nitrogen (N) was 0.62 for ducklings and 0.55 for chickens. Gaseous ammonia-N was 4.5 and 2.2%, respectively, of N retained. 6. In a second experiment groups of ducklings only, were offered high- and low-protein diets from 12 to 22 d of age. Comparisons among four diets showed that food and energy intake was lower on the low-protein diet than on the other three. Energy retention on the high-energy diet was greater (P less than 0.05) than on the other three diets. 7. It was concluded that a high-energy diet is important for ducklings and chickens for maximum biological performance during the first 4 weeks of life.

Animals↗
PubMed1979

Energy and nitrogen metabolism of chickens infected with either Eimeria acervulina or Eimeria tenella.

1. The effects of sublethal infections of E. acervulina and E. tenella on the energy and nitrogen metabolism of groups of five broilers aged 16 d were studied for 16 d in respiration chambers. 2. The metabolisable energy content of the diet for chickens infected with E. acervulina was 0.689 of its gross energy content and N retention was 42.5 g/100 g N intake compared with 0.738 and 47.1 g respectively, in uninfected pair-fed controls. Chickens infected with E. tenella were similarly affected. 3. Efficiency of utilisation of ME by chickens infected with E. acervulina was 0.43 during the first 8 d after infection, and 0.52 during the second 8 d compared with an overall efficiency by non-infected chickens fed ad libitum of 0.73. Maintenance energy requirement of infected chickens was higher during the first 8 d after infection than during the second 8-d period. 4. Body composition measurements showed that of the total gain in weight of chickens infected with E. acervulina, only 7.5 g/kg gain was fat and 213 g/kg was protein compared with 45 g and 210 g respectively for non infected chickens fed ad libitum. 5. E. acervulina and E. tenella infections reduced the apparent digestibility of total mineral, calcium and phosphorus.

Animals↗
PubMed1979

Energy and nitrogen metabolism of chickens subjected to infection and reinfection with Eimeria acervulina.

1. The effects of E. acervulina on energy and nitrogen metabolism were studied in respiration chambers on four groups of four broilers aged 16 d: group C was infected with 1.1 x 10(6) oocysts/bird on day 1 and fed ad libitum, while groups A, B and D were pair-fed to group C to day 16 of the experiment. On day 17, groups A and C were given 5.0 x 10(6) oocysts/bird and fed ad libitum, while group B was pair-fed to group A and group D was pair-fed to group C to the end of experiment on day 32. 2. Dietary ME as a proportion of gross energy (0.68) and N retention (42 g/100 g N intake) were reduced in the infected group C compared with pair-fed controls (0.75 and 49 g, respectively) for the period 1 to 16 d. Subsequent challenge of group C saw no effects on the two variables, but metabolisability (0.65) and N retention (33 g) were significantly reduced in group A when infected for the first time on day 17. 3. The daily heat production and food intake of group A infected for the first time with E. acervulina on day 17, and group B, their pair-fed controls, were reduced during days 20 to 25 but no such reductions were observed in group C, receiving a challenge dose of E. acervulina, and group D, non-infected pair-fed to group C. The efficiency of utilisation of ME for growth of groups C and D was 0.60 over the 17 to 32 d period. 4. Challenge of immune birds did not affect the apparent digestibility of total minerals, calcium and phosphorus.

Animals↗
PubMed1978

The effect of ovariectomy on liver metabolism and maintenance energy requirement of hens.

Six pullets from each of an egg-producing and meat-producing strain were ovariectomised at 12 weeks of age. Ovarian regrowth occurred in two of the egg-producing and four of the meat-producing strain. 2. Measurements of heat production and energy balance were made after peak lay with ovariectomised and sham-operated laying pullets of both strains. Measurements on the ovariectomised pullets were made before and after implantation with oestrogen pellets. 3. Within each strain the ME requirements for maintenance (per kg W0.75), determined by linear regression analysis, were similar whether or not the starvation heat production data were included. 4. The ME requirements for maintenance decreased substantially after ovariectomy but subsequent implantation with oestrogen pellets did not increase these requirements. 5. Studies of hepatic enzyme activities indicated that the major influence of the mature ovary was on hepatic lipid metabolism. This was exerted through a specific stimulation of lipogenesis rather than a general increase in metabolism.

Animals↗
PubMed1977

The in vivo estimation of body fat content in laying hens.

A comparison was made between the determined water space of 16 laying hens weighing between 1-1 and 3-5 kg and that predicted from tritiated water space, with the object of estimating body fat content. 2. The predicted water space over-estimated the determined water space by 15%, but body fat content in living hens with fat levels representing 8-6 and 39% of carcass weight could be predicted with a coefficient of variation of 14%.

Adipose Tissue↗
PubMed1977

A comparison of the energy and nitrogen metabolism of broilers selected for increased growth rate, food consumption and conversion of food to gain.

Calorimetric measurements were made on 5-week-old male chickens sampled from the third generation of three lines selected for either increased live-weight gain (W), food consumption (F), or food conversion efficiency (E). A control line (C) was also measured. 2. Food intake and food conversion ratio were greater (P less than 0-05) in the F line than in the E anc C lines. 3. Metabolisability of the diet was 0-8% higher in the E line than in the other lines. 4. Metabolisable energy (ME) intake and heat production were greater (P less than 0-05) in the F line than in the E and C lines, and energy balance was greater (P less than 0-05) in the F than in the W and E lines. 5. During starvation, excreta energy and heat production were greater (P less than 0-05) in the F than the other lines. 6. Availability of ME (net energy) was the same (85%) for all lines but calculated daily maintenance energy requirements (kJ ME/kgW) were W, 860; F, 937; E, 796 and C, 810. 7. By 9 weeks the F line contained more fat and less water than lines E and C.

Animal Feed↗
PubMed1977

Effects of temperature treatments on the heat production of starving chickens.

1. Heat production was measured for about 24 h at six temperatures from 2 to 35 degrees C on individually starved broilers that had been subjected to four treatments; these were acclimated or unacclimated to these temperatures, or to these temperatures for 12 h and to 22 degrees C for 12 h (alternated) during each 24-h period. 2. Response curves relating heart production and environmental temperature for the four different treatments differed significantly. Only the unacclimated birds subjected to the alternated temperatures increased heat production at 35 degrees/22 degrees C. Major effects of acclimation were observed mainly in the cold. 3. The relationship between daily endogenous nitrogen (N) excretion and heart production (mg N/kJ) was constant at the different temperatures, but acclimation and alternating temperature increased N excretion. 4. Evaporative heat loss was reduced by alternating temperature at the high temperatures, and by maintaining temperature constant in the cold.

Acclimatization↗