Economic analysis of interventions to improve village chicken production in Myanmar.

A cost-benefit analysis using deterministic and stochastic modelling was conducted to identify the net benefits for households that adopt (1) vaccination of individual birds against Newcastle disease (ND) or (2) improved management of chick rearing by providing coops for the protection of chicks from predation and chick starter feed inside a creep feeder to support chicks' nutrition in village chicken flocks in Myanmar. Partial budgeting was used to assess the additional costs and benefits associated with each of the two interventions tested relative to neither strategy. In the deterministic model, over the first 3 years after the introduction of the interventions, the cumulative sum of the net differences from neither strategy was 13,189Kyat for ND vaccination and 77,645Kyat for improved chick management (effective exchange rate in 2005: 1000Kyat=1$US). Both interventions were also profitable after discounting over a 10-year period; Net Present Values for ND vaccination and improved chick management were 30,791 and 167,825Kyat, respectively. The Benefit-Cost Ratio for ND vaccination was very high (28.8). This was lower for improved chick management, due to greater costs of the intervention, but still favourable at 4.7. Using both interventions concurrently yielded a Net Present Value of 470,543Kyat and a Benefit-Cost Ratio of 11.2 over the 10-year period in the deterministic model. Using the stochastic model, for the first 3 years following the introduction of the interventions, the mean cumulative sums of the net difference were similar to those values obtained from the deterministic model. Sensitivity analysis indicated that the cumulative net differences were strongly influenced by grower bird sale income, particularly under improved chick management. The effects of the strategies on odds of households selling and consuming birds after 7 months, and numbers of birds being sold or consumed after this period also influenced profitability. Cost variations for equipment used under improved chick management were not markedly associated with profitability. Net Present Values and Benefit-Cost Ratios discounted over a 10-year period were also similar to the deterministic model when mean values obtained through stochastic modelling were used. In summary, the study showed that ND vaccination and improved chick management can improve the viability and profitability of village chicken production in Myanmar.

Evaluation of strategies to improve village chicken production: controlled field trials to assess effects of Newcastle disease vaccination and altered chick rearing in Myanmar [corrected].

Previous research identified Newcastle disease and poor management of chicks (birds younger than 6 weeks of age) as major constraints to village chicken production in Myanmar. Based on these findings, controlled trials were conducted in 124 randomly selected households in nine villages in Myanmar over a period of 12 months to evaluate strategies to enhance survival of village chickens. Two intervention strategies were assessed: Newcastle disease vaccination using the thermostable I-2 vaccine and changes to the management of chick rearing (confinement and supplementary feeding). These interventions were applied in two trials: (1) a randomised controlled trial to compare I-2 vaccination, altered chick management and no intervention (apart from placebo treatment) at household level and (2) nested within this trial, a double-blinded controlled trial at bird-level to compare serological titres between I-2 vaccinated and placebo-treated birds both between and within households. Outcomes measured in the first trial were crude incidence rate of mortality, proportional mortality rate for deaths due to disease stratified by age group of birds and mortality attributed to Newcastle disease, number of sales, income from sale of birds, consumption of birds and hatching of birds. Odds of having protective titres two weeks after vaccination were up to 125 times higher in I-2 vaccinated birds and up to 47 times higher in control birds in contact with I-2 vaccinates compared to birds without I-2 contact. Vaccination against Newcastle disease reduced the proportions of mortalities assumed to be caused by disease in growers and chicks. Crude mortality incidence was lower in households that applied management changes to chick rearing. In household-months when birds were sold, numbers sold were higher and income from sale of birds were about 2.50 US dollars per month higher in households allocated to altered chick management. Altered chick management resulted in more households having hatchings of chicks. After a lag period of 7 months, these households were also more likely to consume home-produced chicken meat. This 7-month period reflects the age when birds are consumed and sold and highlights the lag periods that should be expected before beneficial effects of interventions focussed on chicks occur. This field research has shown that I-2 vaccination markedly increases the prevalence of protective titres and reduces proportions of mortality attributed to disease and that chick management using confinement and supplementary feeding can improve health and production of village chickens. These interventions are simple and sustainable intervention strategies.

Protein utilisation and turnover in lines of chickens selected for different aspects of body composition.

1. Protein utilisation and turnover were measured in male chickens sampled from a line selected for high breast yield and a randombred control line (lines QL and CL, experiment 1) and in male chickens sampled from lines selected for either high or low abdominal fatness (lines FL and LL, experiment 2). In each experiment, 18 birds per line were given iso-energetic (12.9 MJME/kg) diets containing either 120 or 220 g CP/kg from 21 to 29 d (experiment 1) and 33 to 43 d (experiment 2). 2. Measurements were made of growth rate, food intake, body composition, excreta production and Ntau-methylhistidine excretion as a measure of myofibrillar protein breakdown, and fractional rates (%/d) of protein deposition, breakdown and synthesis were calculated. 3. In experiment 1, there were no significant differences between the line means for the fractional measures of protein turnover, but there was marked differential response in the two lines in the fractional rates of protein deposition, breakdown and synthesis, to increase in protein intake. The positive slope of the regressions of fractional (%/d) protein deposition and synthesis rates on protein intake (g/d/kg BW) were approximately 1.4- and 2.0-fold higher respectively in the QL than the CL line birds, and the negative slope of the regression of fractional breakdown rate on protein intake was approximately threefold greater in the CL than the QL line birds. 4. In experiment 2, fractional deposition rate was 6.2% lower, but fractional breakdown rate 9.4% higher in the LL than the FL birds, whilst there was essentially no difference in response of the FL and LL birds in the components of protein turnover to increase in protein intake. Line differences in deposition and breakdown rates were thus a reflection of the considerably higher (20%) food and hence protein intake in the FL than the LL birds. 5. The differential line responses in protein turnover in the two experiments suggest that selection for increased breast muscle yield and for reduced body fatness manipulate different physiological pathways in relation to protein turnover, but neither selection strategy results in an improvement in net protein utilisation at typical levels of protein intake by birds on commercial broiler diets, through a reduction in protein breakdown rate.

Response of broilers selected on carcass quality to dietary protein supply: live performance, muscle development, and circulating insulin-like growth factors (IGF-I and -II).

The effect of dietary protein supply on muscle development and circulating concentrations of insulin-like growth factors (IGF)-I and -II was examined in chickens selected for increased breast yield and decreased fatness (quality, QL) and in its control line (CL). CL and QL chickens were fed isoenergetic diets containing 121.5 or 215.8 g CP/kg during a 12-d period; comparisons were performed at 33 d of age. Birds given the high protein diet grew faster, ate less feed, had lower feed conversion ratio (FCR), and higher muscle weights than their counterparts given the low protein diet. The muscle weight response to protein supply differed between muscles in both lines, with pectoralis major appearing more sensitive than sartorius. The response of the gastrocnemius muscle depended on the line. Selection for carcass quality increased (P < 0.01) body weight, growth rate, feed intake, pectoralis major and sartorius muscle weights, and pectoralis major muscle proportion. There was, however, no line difference in FCR or in sartorius muscle proportion. The weight and proportion of the gastrocnemius muscle were higher (P < 0.05) in the QL than the CL chickens on the high protein diet, but there was no line difference for the low protein diet. Plasma levels of IGF-I, and to a lesser extent IGF-II, were lower (P < 0.01) in protein-restricted chickens. No difference in circulating IGF-II was observed between the lines. Concentrations of IGF-I were higher (P < 0.05) in QL than CL chickens, which may contribute to improved body composition for this genotype.

Transcripts of the MHM region on the chicken Z chromosome accumulate as non-coding RNA in the nucleus of female cells adjacent to the DMRT1 locus.

The male hypermethylated (MHM) region, located near the middle of the short arm of the Z chromosome of chickens, consists of approximately 210 tandem repeats of a BamHI 2.2-kb sequence unit. Cytosines of the CpG dinucleotides of this region are extensively methylated on the two Z chromosomes in the male but much less methylated on the single Z chromosome in the female. The state of methylation of the MHM region is established after fertilization by about the 1-day embryonic stage. The MHM region is transcribed only in the female from the particular strand into heterogeneous, high molecular-mass, non-coding RNA, which is accumulated at the site of transcription, adjacent to the DMRT1 locus, in the nucleus. The transcriptional silence of the MHM region in the male is most likely caused by the CpG methylation, since treatment of the male embryonic fibroblasts with 5-azacytidine results in hypo-methylation and active transcription of this region. In ZZW triploid chickens, MHM regions are hypomethylated and transcribed on the two Z chromosomes, whereas MHM regions are hypermethylated and transcriptionally inactive on the three Z chromosomes in ZZZ triploid chickens, suggesting a possible role of the W chromosome on the state of the MHM region.

Insulin-like growth factor (IGF)-I but not IGF-II promotes lean growth and feed efficiency in broiler chickens.

The efficacy of exogenous IGFs to stimulate growth and modulate protein and fat deposition was examined in a number of broiler chicken lines. From around 600 g body weight the chickens received a continuous infusion of vehicle (0.1 M acetic acid), human recombinant IGF-I or [Gly1]IGF-II at 300 microg/kg body weight per day, or a combined infusion of 150 microg/kg/day of each IGF for 2 weeks. Experiment 1 used commercial broiler female chickens and included measurements of nitrogen balance, Ntau-methylhistidine excretion and muscle protein synthesis rates. In Experiment 2 the same treatments were applied to three experimental lines of chickens selected for high food consumption (relatively fat), high food utilisation efficiency (relatively lean), or at random (control). IGF-I, but not IGF-II, significantly increased growth rate and food utilisation efficiency by around 10-15% in each experiment, an effect which was consistent across all genotypes. Nitrogen balance was significantly increased by IGF-I in Experiment 1 as was carcass nitrogen content in Experiment 2, indicating that the increased growth was in lean tissue. Carcass fat was consistently reduced in chickens receiving IGF-I and was related to the levels of circulating IGF-I (r2 = 0.30, P < 0.01) but not triiodothyronine. Protein synthesis rates were unaffected by treatment and could not account for increased growth rate. However, there was a significant reduction in Ntau-methylhistidine excretion indicating a reduced rate of muscle protein breakdown in IGF-I-treated chickens (1. 56%/day vs 2.05%/day for IGF-I-treated vs controls, P < 0.05). The efficiency of feed utilisation was inversely related to the rate of protein breakdown (r2 = 0.25, P < 0.01). In conclusion, these experiments are the first to report an enhancement of growth and food utilisation efficiency by broiler chickens receiving exogenous IGF-I. Our results show that IGF-I may be important in controlling the growth and efficiency of food utilisation of young chickens at least in part by modulating the rates of protein breakdown.

Inheritance of plasma insulin-like growth factor-I and growth rate, food intake, food efficiency and abdominal fatness in chickens.

1. The inheritance of, and genetic and phenotypic correlations between, plasma insulin-like growth factor-I (IGF-I) and 28-(28dW) and 56-d (56dW) body weight, 28- to 56-d body weight gain (BWG), food intake (FI), food conversion ratio (FCR) and abdominal fatness (AF) at 56 d were determined by sib analyses in a population of 327 pedigreed progeny produced by matings between 18 cockerels and 72 pullets from a broiler strain of chickens bred at random for 8 generations. 2. Plasma IGF-I was measured in fed (IGF-If) and fasted (IGF-I) birds at 42 d. 3. Heritability estimates (sire + dam) were: 28dW 0.35 +/- 0.11, 56dW 0.49 +/- 0.13, BWG 0.51 +/- 0.13, FI 0.55 +/- 0.13, FCR 0.73 +/- 0.14, AF 0.49 +/- 0.13, IGF-If 0.10 +/- 0.08, IGF-Is 0.08 +/- 0.08. 4. The low heritability estimates with their high standard errors for the IGF-I measures precluded the calculation of meaningful genetic correlations between these and the performance traits. There were moderate to strong positive genetic correlations between 28dW, 56dW, FI and AF.

Muscle protein turnover in chickens selected for increased growth rate, food consumption or efficiency of food utilisation: effects of genotype and relationship to plasma IGF-I and growth hormone.

1. Rates of muscle protein turnover, growth, and food consumption were determined in 4 lines of chickens selected for either weight gain (line W), food consumption (line F), efficiency of food conversion (line E), or at random (line C) and in two Australian commercial broiler strains (S and H). These measures were related to body composition and the circulating concentrations of plasma growth hormone (GH) and IGF-I. 2. N tau-methylhistidine excretion was 10-14% higher in line F and 7-13% lower in line E compared to line C, showing divergence in the rate of muscle protein breakdown with selection. 3. There were no differences between the 4 experimental lines (W, F, E and C) in muscle protein fractional synthesis rates, whether calculated from N tau-methylhistidine excretion or measured directly by 3H-phenylalanine incorporation. 4. No consistent differences were found between lines in circulating concentrations of either GH or IGF-I but plasma IGF-I concentrations were positively correlated over all lines with protein accretion rates. There was a strong inverse correlation over all lines between the rates of protein degradation and FCR. 5. The correlated responses in protein degradation rates are consistent with the notion of a positive genetic association between the overall efficiency of food utilisation for growth and the efficiency of protein metabolism.

The effect of dietary calcium upon growth rate, food utilisation and plasma constituents in lines of chickens selected for aspects of growth or body composition.

1. The effect of increasing dietary calcium from 10.3 to 20 g/kg on 5- to 17-day growth performance and plasma minerals, electrolytes, total protein, albumin and glucose in chickens from 4 lines selected for: high 8-week body weight (W), low abdominal fat (L), high abdominal fat (F) or at random (C) was studied in two experiments. 2. High dietary calcium significantly reduced weight gain and plasma phosphate and potassium but increased food:gain ratio, plasma total calcium, glucose and albumin. 3. Significant correlations were found between plasma total calcium and plasma phosphate (r = -0.5, P less than 0.01), plasma total calcium and protein (r = 0.4, P less than 0.01) and between plasma total protein and albumin (r = 0.55, P less than 0.01). 4. Genotypes differed in their response to dietary calcium content. There was a substantial response in line F but little effect in line L. 5. In contrast to the three other lines, in line F high dietary calcium significantly increased plasma ionised calcium without altering plasma phosphate or total calcium concentration. 6. It was concluded that genetic selection has produced lines which vary in their tolerance to high dietary concentrations of calcium. Birds selected for increased fatness were less tolerant to high dietary calcium than their lean-selected counterparts.

Effects of dietary calcium, available phosphorus and vitamin D on growth rate, food utilisation, plasma and bone constituents and calcium and phosphorus retention of commercial broiler strains.

1. The effects of different dietary concentrations of calcium (Ca), available phosphorus (AP) and vitamin D (D) on 5- to 16-day growth performance, and aspects of calcium and phosphorus (P) metabolism of chickens from three commercial strains were studied in two experiments. 2. Increasing dietary Ca reduced weight gain, tibia Ca and P content and increased plasma total Ca, Ca consumption and excretion, whilst dietary Ca at 32 g/kg increased tibia Ca:P ratio, plasma ionized calcium and reduced plasma P, tibia ash, P excretion, excreta moisture and Ca retention. 3. Increasing dietary AP reduced plasma total and ionized Ca and excreta moisture and increased P consumption and excretion, plasma P and tibia ash. 4. The addition of vitamin D increased plasma total and ionized Ca, tibia Ca:P ratio and reduced plasma sodium and P concentrations. 5. Strains differed in their tibia contents of Ca and Ca:P ratios, in response to Ca, AP and vitamin D diets whilst they differed in Ca excretion and excreta moisture caused by feeding either dietary Ca or AP. 6. It was concluded that dietary Ca, AP, vitamin D and strain of broiler chickens influenced the metabolism of Ca and P and that, as a consequence, the tolerance to high dietary Ca. A lean strain of chickens tolerated high dietary calcium better than its fat counterparts.

Rates of muscle protein breakdown in chickens selected for increased growth rate, food consumption or efficiency of food utilisation as assessed by N tau-methylhistidine excretion.

1. N tau-methylhistidine excretion, growth rate, food consumption and body composition was determined in 12 4 to 5 week old chickens sampled from each of 4 lines selected for increased body-weight gain (line W), for increased food consumption (line F), for improved efficiency of food utilisation (line E) or at random (line C), after 12 generations of selection. 2. The use of N tau-methylhistidine as an index of myofibrillar protein breakdown was validated in male and female chickens of lines E and F by following the fate of injected N tau-(14CH3)methylhistidine. Most of the radioactivity (79.3 +/- 1.1%) was excreted in 4 d, with the remainder retained in the carcase. In excreta, 94 +/- 2% of the radioactivity was associated with free N tau-methylhistidine and for the carcase, this value was 88 +/- 3%. 3. In the main experiment, final body weights averaged 497, 651, 588 and 537 g and food: gain ratio averaged 2.47, 2.21, 3.14 and 2.06 for lines C, W, F and E respectively, Carcase protein content (g/100 g body weight) was not different between the lines. 4. N tau-methylhistidine excretion was 5.86, 5.48, 6.43 and 4.99 mumoles/mole carcase-N/d for lines C, W, F and E, respectively. The rate for line F was significantly higher than for lines W and C and that for line E was significantly less than for the control line. 5. The N tau-methylhistidine excretion rate was positively correlated with food: gain ratio. 6. Selection for rapid growth, high food consumption or improved food utilisation results in changes in N tau-methylhistidine excretion which suggest proportionate changes in muscle protein turnover.

Energy and nitrogen metabolism of broilers selected over ten generations for increased growth rate, food consumption and conversion of food to gain.

Energy and nitrogen (N) metabolism were studied in 6-week-old male birds taken from 4 lines of chickens selected for 10 generations for increased weight gain (line W), increased food consumption (line F), increased conversion of food to gain (line E) or at random (controls, line C). Calorimetric measurements were made 8 times on each line while fed ad libitum in large open-circuit respiration chambers for 3 d, and 11 to 13 times without food in smaller closed-circuit respiration chambers for 24 h. The F line ate 60% more food, produced 90% more excreta and 34% more heat and retained 80% more energy and 35% more N in their bodies than lines E and C. Line W was intermediate. When differences in body weight were taken into account, the E and W lines had lower heat production than the C line, while the F line ate 40% more food, produced 30% more heat and retained 70% more energy and 30% more N than the E line. In lines W, F, E and C respectively, the mean metabolisability of dietary energy (%) was 69.4, 62.9, 70.1 and 67.8; the fasting heat production (mean +/- SE) was 481 +/- 9, 569 +/- 10, 485 +/- 9, and 508 +/- 9 kJ/kgW d; the net availability of metabolisable energy (NAME) was 0.68 +/- 0.05, 0.76 +/- 0.04, 0.85 +/- 0.06 and 0.73 +/- 0.04; the estimated daily maintenance energy requirements were 671 +/- 15,866 +/- 14,701 +/- 13, and 742 +/- 11 kJ ME/kgW; and the proportion of N retained per unit increase in N intake was 0.38 +/- 0.08, 0.50 +/- 0.06, 0.56 +/- 0.10 and 0.53 +/- 0.06. The contribution of line differences in the above traits to large line differences in efficiency of food utilisation is discussed.

Comparison of plasma very low density lipoproteins and lipogenic enzymes as predictors of fat content and food conversion efficiency in selected lines of broiler chickens.

Activities of lipogenic enzymes and plasma very low density lipoprotein (VLDL) concentrations were measured in lines of chickens with large differences in food conversion efficiency (FCE) and body fat. Hepatic activities of malate dehydrogenase [EC 1.1.1.40 (MD)] and ATP citrate lyase [EC 4.1.3.8 (CL)] were correlated with the proportion of both abdominal and total body fat (r = 0.50) but were poorly correlated with gain: food ratio. Activities of MD and CL in plasma were low and variable and were not correlated with any other characteristics. Plasma VLDL concentration was significantly correlated with the proportion of abdominal and total body fat (r = 0.59), and gain: food ratio (r = 0.36).

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.

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.