Green and Blue Monochromatic Lights Promote Growth and Development of Broilers Via Stimulating Testosterone Secretion and Myofiber Growth

Methods of light treatment such as light schedule, intensity or illuminance, and color are important factors that influence avian productivity. Therefore, artificial illumination has been widely used in modern poultry husbandry. Although progress had been made in understanding of the effects of light schedule and intensity on avian growth, effects of light color on avian growth are not clear. In this study, 276 male Arbor Acres broilers were reared under white, red, green, and blue lights from light-emitting diode lamps as light sources. Broilers’ growth and productive performance were increased under green light during the early period (0 to 26 d of age) or blue light during the later period (27 to 49 d of age). Furthermore, both blue and green lights were more effective to stimulate testosterone secretion and myofiber growth that led to increased body growth. These results indicate that light-emitting diode lamps have value in the modern broiler husbandry.     

Is there a benefit from an early booster vaccination in the control of equine influenza?

Conventional equine influenza vaccination schedules consist of a primary course of two vaccinations given 4-6 weeks apart followed by a third vaccination (booster) given approximately 5 months later. In between the primary course and the third vaccination, horses are generally considered not to be adequately protected against influenza. This study aimed to investigate whether Thoroughbred foals would benefit from a vaccination schedule in which the third vaccination was given earlier than in conventional vaccination schedules. The vaccines used were an inactivated whole virus equine influenza vaccine and an inactivated whole virus combination vaccine containing equine influenza and equine herpesvirus antigens. Four groups of foals were vaccinated with the two vaccines according to a conventional and an accelerated vaccination schedule in which the third vaccination was given 14 weeks after the first administration. In both groups, the fourth vaccination was given at the normally recommended interval of 26 weeks after the third vaccination for the combination vaccine and 52 weeks after the third vaccination with the influenza only vaccine. The horses were 4-11 months of age and seronegative for influenza. Immunological responses after vaccination were monitored for several months using the single radial haemolysis test. The results indicated that 28 weeks after the first vaccination, antibody levels in horses vaccinated according to the accelerated schedule were not significantly higher than in horses vaccinated according to the conventional schedule. In addition, the total level of antibody production (area under the curve) was not significantly different at that point although antibody titres were slightly higher (but not significantly so) between 16-30 weeks in the accelerated schedule. Between the third and fourth doses, horses vaccinated according to the accelerated schedule had antibodies against influenza below the level required for clinical protection for 39 and 18 weeks for the influenza only and the combination vaccine, respectively, whereas those vaccinated according to the conventional schedule had antibody titres below the level for clinical protection for 9-15 weeks in the corresponding period for both vaccines. Horses vaccinated according to the accelerated schedule with the combination vaccine had lower antibody titres after the fourth vaccination than those vaccinated according to the conventional schedule after the third vaccination, although antibody titres prior to vaccination were similar. For the influenza only vaccine, titres after the accelerated fourth administration were not different to those after the conventional third vaccination. There was no benefit from early booster vaccinations with the vaccines used in this study, so for these vaccines the conventional schedule provided better protection than the selected accelerated alternative. This may contrast with some other vaccine formulations, although a direct comparison using similar protocols has not been made.     

A field trial to assess the effect of vaccination against feline herpesvirus, feline calicivirus and feline panleucopenia virus in 6-week-old kittens.

A trivalent (feline panleucopenia, feline herpesvirus, feline calicivirus), modified live, commercially available cat vaccine was used at either 6, 9 and 12 weeks of age (early schedule) or 9 and 12 weeks of age (conventional schedule), and the serological response to vaccination was assessed. The level of maternally derived antibody present at 6 weeks of age was also established. The use of early vaccination at 6 weeks of age induced an antibody response to each virus by 9 weeks of age in a significant proportion of kittens compared with unvaccinated littermates. There was no difference between the conventionally and early-vaccinated groups in terms of antibody response to any antigen by 12 and 15 weeks of age.     

Differences in Pulmonary Functional Indices Derived from the Single-Breath Diagram for CO2 (SBD-CO2) in Horses Related to Age,Sex and Usage

Although pulmonary function tests have been used to evaluate horses with clinically normal lungs and those with recurrent airway obstruction (RAO), comprehensive studies of equine respiratory function, considering factors such as sex, age and usage are not available. Studies on the influence of these factors on pulmonary function in healthy horses are required for interpretation of measurements made in those with respiratory disease. The study was performed with 63 warmblood horses and the status of their pulmonary health was evaluated by clinical examination. The functional aspect of pulmonary health was assessed by indices derived from the single-breath diagram for CO₂ (SBD-CO₂). Differences in pulmonary functional indices between the sexes, age groups and usage groups adjusted for pulmonary health were analysed with hierarchical linear models. It was shown that the effects on pulmonary function of age, sex and usage of a horse were significant and have to be considered when establishing the true pulmonary functional status of a horse suffering from RAO. The multivariate statistical model used included the covariates age, sex and sporting discipline of the horses and accounted for the complex, non-linear interactions between the different covariates.     

Growth performance of Hubbard × Cobb 500 and Ross × Ross 708 male broilers fed diets varying in apparent metabolizable energy from 14 to 28 days of age

The cost of energy-contributing ingredients has increased over the last several years. Defining minimum dietary energy specifications for broilers is a strategy to mitigate high diet cost. Two experiments were conducted to evaluate the effects of diets with graded concentrations of AME_n fed to Hubbard × Cobb 500 (experiment 1) and Ross × Ross 708 (experiment 2) male broiler chicks from 14 to 28 d of age. Both experiments were identical in experimental procedures with the exception of genetic strain. Broilers were fed a common corn-soybean meal-based starter diet from 1 to 13 d of age. At 14 d of age, dietary treatments were provided with 1 of 6 concentrations of AME_n (3,000, 3,030, 3,060, 3,090, 3,120, and 3,150 kcal/kg). In experiment 1, BW gain, feed intake, and FCR of Hubbard × Cobb 500 broilers decreased linearly with increasing AME_n. Linear broken-line response of FCR was estimated at 3,062 kcal of AME_n/kg based on broken-line methodology. In experiment 2, Ross × Ross 708 broilers did not respond to graded concentrations of energy, as indicated by linear and quadratic regression of BW gain, feed intake, caloric conversion, and FCR data. Therefore, Hubbard × Cobb 500 male broilers respond to AME_n from 14 to 28 d of age and may be fed diets formulated at 3,062 kcal of AME_n/kg without loss of performance. Conversely, growth performance of Ross × Ross 708 male broilers was not affected by varying AME_n (3,000 to 3,150 kcal/kg) from 14 to 28 d of age. In addition, the response to AME_n may not be as pronounced with the modern broiler compared with broilers used in previous research.     

Arterial Acid-Base Measurements in 1–3 Days Old Piglets

A method of percutaneous arterial blood sampling in piglets has been developed and determinations of arterial pH, pCO₂, pCO2, BE, HGO3 , LA and Hb have been performed in 121 piglets 1–3 days of age. The validity of these measurements has been tested and proved valid for clinical practice with the exception of pO₂ and LA values. The correlations with age were statistically significant but poor and therefore the mean values are presented as reference values. These were: pH: 7.423±0.082, PCO₂: 4.98±0.74 kPa, BE: 0.4±4.1 mmol/1, HCO³_‒: 23.0+3.2 mmol/1 and Hb: 88±14 g/1.     

Characterizing behavioral sleep using actigraphy in adult dogs of various ages fed once or twice daily

Adult dogs possess strong diurnal locomotor activity/rest rhythms, and sleep/wake patterns have been characterized. However, behavioral sleep/wake data are lacking related to aging and daily feeding pattern. Three groups (young adults [Y], 1.5–4.5 years; middle-aged adults [M], 7–9 years; and senior, 11–14 years) of beagles (N = 48) wore the Actiwatch activity monitoring system (Respironics Co., Inc., Bend, OR) for 3 days while housed indoors with 12-hour light/dark schedule and fed once or twice daily. Actiware-Rhythm software (version 5.52; Respironics Co., Inc., Bend, OR) was used to estimate behavioral sleep or wake from locomotor activity data. All dogs demonstrated diurnal sleeping patterns. Total wake minutes during the light phase declined with age (P < 0.05) and differed by 7.7% and 10.2% for middle-aged adults and seniors, respectively, compared with young adults. Further analysis revealed that increased light phase nap bouts (P < 0.008), not increased nap duration, caused this decline. Total sleep minutes during the night increased with age, as middle-aged adults and seniors slept at least 38 (P = 0.01) more minutes than young adults. Increased sleep time at night resulted from a longer sleep interval duration (P = 0.05), delayed morning activity onset time (P = 0.02), and marginally fewer waking bouts (P = 0.07). Independent of age, twice-daily feeding significantly influenced daytime sleeping patterns but did not affect total minutes recorded as sleep during the day. Interestingly, napping bouts decreased significantly (P = 0.01) and napping duration increased (P = 0.0001) when fed twice-daily. Twice-daily feeding was also associated with earlier sleep onset time at night and onset of morning activity, as well as shortened sleep interval. Clear changes in behavioral sleep patterns were observed with age and daily feeding schedule.     

Flock dynamics of desert Barki sheep in relation to age structure

Reproduction data of 8689 ewe records spread over 40 years (from 1960 to 2000) representing 2952 breeding Barki ewes were used in this study. The flock belonged to the Desert Research Center in Egypt. Flock dynamics of nine age groups (2–10 yrs) were assessed. Two parameters were used to evaluate flock dynamics, net reproduction rate (R_o) (number of ewe- lambs reaching joining age and produced by each ewe during its lifetime in the flock) and intrinsic rate of increase (r_m) (flock growth when no resource is limiting). Age of ewe had a highly significant (P < 0.01) effect on number of ewes lambing per ewe joined (E_PJ), number of lambs born per ewe joined (L_BJ), number of lambs weaned per ewe joined (L_WJ) and number of ewe lambs reaching joining age per ewe joined (L_EJ.J). All estimates tended to increase with dams age up to four years and decreased thereafter. The results of R_o and r_m showed that the studied flock must consist of 5 age groups to maintain its size and replace itself. It may be recommended to cull the breeding ewe at the age of 6 years to accelerate genetic improvement.     

Adjustment of test-day milk,fat and protein yield for age,season and stage of lactation

The object of this study was to develop a method for the adjustment of test-day milk, fat and protein yield for age at calving, stage of lactation, and month of calving. Test-day records of 14 275 purebred Dutch Friesians were analysed by generalized least squares, (GLS). Functions of days in lactation and age in months were fitted to the age differences for different stages in lactation. A close fit to the GLS means was obtained for both milk fat and protein yield. From these functions, adjustment factors (CF_ageI) were computed depending on the cow's age in months and number of days in lactation. A multiplicative adjustment for age and stage of lactation by CF_ageI was compared with an adjustment using factors derived from the constant estimates (CF_ageII). Comparison was on the F-variable and constant estimates for age after adjustment. When CF_ageI was used instead of CF_ageII, lower F-values were obtained and the constants showed a more regular pattern. Additive adjustment factors for month of calving were derived from the GLS constant estimates. After correction, month of calving was only significant for protein yield. The adjustment of test-day yields for age at calving and stage of lactation was improved by using mathematical functions.     

Beneficial effects of alternative lighting schedules on the incidence of ascites and on metabolic parameters of broiler chickens

The beneficial effects of different lighting programmes on the incidence of ascites was investigated in an experiment with 360 three-day-old male broiler chickens. At 3 days of age, chicks were randomly divided over three rooms in a high-altitude farm, 2000 m above sea level. During days 14 to 28 ambient temperature decreased during the night but the minimum temperature did not descend below 15 degrees C. In the first room the continuous lighting schedule (CL, 23L:1D) was maintained and in the second room an intermittent lighting schedule (IL, 1L:3D), repeated six times daily, was imposed from 3 days of age. In the third room, an increasing photoperiod schedule (IP, 4 to 14 days, 6L:18D; 15 to 21 days, 10L:14D; 22 to 28 days, 14L:10D; 29 to 35 days, 18L:6D; 36 to 42 days, 23L:1D) was provided. Mortality associated with right ventricular failure and ascites was numerically lower in birds reared under the IL and IP schedules compared to birds reared under the CL schedule, which can be attributed to the temporary reduction in relative growth and feed intake in IL and IP birds. It was concluded that the beneficial effect of lighting schedules could be due to a reduced metabolic rate as a consequence of the altered growth trajectory, as also reflected in the lower haematocrit and plasma T3 levels of IL and IP birds compared to CL birds.     

Kinetics of solutes and particles of different size in the digestive tract of cattle of 0.5–10 years of age,and relationships with methane production

The digestive physiology of cattle is characterised by comparatively long digesta mean retention times (MRTs), a particle sorting mechanism (difference in MRTs of large vs. small particles) and a distinct digesta washing (difference in MRTs between particles and fluids) in the reticulorumen (RR). How these processes mature during ontogeny, and how they link to other digestion characteristics and methane production, is largely unknown. We used a set of passage markers (Co‐EDTA for fluids and hay particles of 2, 5 and 8 mm length mordanted with Cr, La and Ce, respectively) to measure MRTs in 12 heifers (0.5–2.1 years; hay only) and two groups of 15 lactating cows (2.4–10.0 years; forage‐only vs. forage‐concentrate diet). The MRTs differed between markers (Co < Cr < La < Ce) and were longer in heifers than cows, consistent with the lower feed intake in heifers. MRTs were mostly similar between cow groups and increased with age. Digesta washing was not affected by group, age, feed intake and number of chews per unit of feed. The degree of digesta washing was not related to CH₄ measures. Particle sorting was more prominent in cows than heifers but did not differ between cow groups or change with age in cows. This could be the consequence of the abrupt increase in intake from heifers to cows at a time when gut capacity is not yet fully developed; particle sorting might then clear smaller particles from the RR sooner allowing a higher intake. Surprisingly, CH₄ yield per ingested feed did not correlate with MRTs, and CH₄ yield per unit of digested fibre decreased with increasing MRTs and with increasing fibre digestibility. As this pattern occurred in heifers and both cow groups, it appeared independent of age, indicating a mechanism that has not been described in the literature so far and requires further investigation.     

Effects of distillers dried grains with solubles and mineral sources on gaseous emissions

Distillers dried grains with solubles (DDGS), an important ethanol industry co-product, has been used as a high-protein feed in poultry production. Limited studies exist on their effect on air emissions, however. In the current study, 4 diets (2 × 2 factorial design: 0 or 20% DDGS + inorganic or organic mineral sources) were fed to Hy-line W36 hens from 50 to 53 wk of age and the effects of DDGS level and mineral sources on air emissions were monitored continuously for a 23-d period in environmentally controlled chambers. The NH₃, H₂ S, CH₄, nonmethane hydrocarbons, N₂ O, CO₂, and CO₂-equivalent emissions ranged from 0.51 to 0.64 g/day-hen, 0.71 to 0.84 mg/day-hen, 33.9 to 46.0 mg/day-hen, 54.1 to 60.0 mg/day-hen, 66.0 g to 72.2 g/day-hen, and 83.1 to 92.1 g/day-hen, respectively. Feeding DDGS to laying hens resulted in 14% decreased NH₃ emissions but a 19% increase in CH₄ emissions without affecting other gaseous emissions. More than 30% of N, 80% of P, 80% of K, and 50% of Ca was retained in the manure. In conclusion, feeding laying hens a diet containing 20% DDGS may be beneficial for the environment. Substitution for organic trace minerals did not affect hen performance or air emissions.     

Localization of aromatase in Equine Leydig cells

Stallion testes secrete large amounts of estrogens, but the cellular location of the enzyme that converts androgens to estrogens, cytochrome P₄₅₀ aromatase, has not been determined. The goal of the present study was to immunocytochemically localize stallion testicular aromatase using a polyclonal antibody generated against human placental cytochrome P₄₅₀ aromatase. Testes were obtained from 12 stallions from 2 to 23 years of age, during both the breeding and non-breeding seasons. Immunoreactivity was confined to the Leydig cells in all testes examined. No immunostaining was observed in the Sertoli or germ cells. Heterogeneity in the level of immunostaining among individual Leydig cells was observed. The results of this study indicate that in postpubertal, adult, and aged stallions, testicular aromatase is located in Leydig cells.     

Indirect assessment of dihydropyrimidine dehydrogenase activity in cats

Use of 5‐fluoropyridimine antimetabolite drugs, specifically 5‐fluorouracil (5‐FU), has been discouraged in cats because of adverse events including neurotoxicity and death. Causes of toxicity have never been elucidated. In humans, toxicity has been associated with ineffective metabolism secondary to deficiencies in dihydropyrimidine dehydrogenase (DPD). Direct assessment of DPD activity is challenging; determination of uracil:dihydrouracil (U:UH₂) in plasma using high performance liquid chromatography (HPLC) has been reported as an indirect measurement. U:UH₂ was measured in the plasma of 73 cats. Mean U:UH₂ for all cats was 1.66 ± 0.11 (median 1.53, range 0.24–7.00). Seventeen (23%) cats had U:UH₂ >2, a value associated with decreased DPD activity in humans. Spayed female cats had significantly lower U:UH₂ as compared with intact females, and age and U:UH₂ were weakly but significantly negatively correlated (r = ?0.26). Studies correlating U:UH₂ and 5‐FU tolerability are required to further determine the validity and use of this test in cats.     

Nutrient oxidation and lipogenesis in hens

Introduction Indirect calorimetry based on measurements of gas exchange has been used successfully during the last century in order to estimate energetic values of feedstuffs and animals’ requirement for nutrients and energy. Recently, measurements of gas exchange have been used to calculate nutrient oxidation and lipogenesis in the intact body of man (T horbek et al. 1994), pigs (C hwalibog et al. 1992; C hwalibog and T horbek 1995), calves (C hwalibog et al. 1996; C hwalibog et al. 1997a), mink (T auson et al. 1997) and rats (C hwalibog et al. 1998). In the present paper a similar approach has been used to quantify nutrient metabolism in laying hens in accordance with a calculation method first proposed by C hwalibog et al. (1992) and later modified as outlined in Fig. 1. According to this biological model digested protein (DP) which is equal to PROT _{– group} is utilized for retention in eggs (OP), ovary and body (OBP), whereas deaminated amino acids are oxidized (OXP) with concomitant excretion of energy with nitrogenous substances in urine (UE_N) and contribution of energy (GLUC) to carbohydrate metabolism. Digested carbohydrate (DCHO) together with GLUC constitute the CHO _{– group}, which is retained in eggs (OCHO), oxidized (OXCHO) and used for lipogenesis (LIPO). Digested fat (DFAT) and lipids from lipogenesis constitute the FAT _{– group}, which is incorporated into eggs (OF), ovary + body (OBF) and oxidized (OXF). Both CHO and FAT metabolism contribute with energy containing products excreted with urine (UE_N-free). The energy from OXP, OXCHO and OXF make up the total heat production (HE). The validity of the method will be discussed later. The aim of this study was to demonstrate how data from gas exchange measurements in combination with nitrogen and energy balances can be applied in order to calculate nutrient oxidation and the quantities of substrates used for retention and lipogenesis processes, and furthermore, to elucidate differences in nutrient oxidation and lipogenesis in relation to different housing conditions and genotypes of laying hens.     

An investigation of the possible effects of subclinical iodine deficiency on ewe fertility and perinatal lamb mortality

A controlled supplementation trial was performed in an assumed iodine-deficient Romney ewe flock in the Manawatu. Significantly more twin litters were born to iodine-supplemented ewes than to control ewes. Furthermore, the perinatal mortality rate in lambs born to iodine-supplemented dams was significantly lower than in lambs born to control dams. Ewe age and the use of different lambing paddocks for iodine-supplemented and control ewes may have been confounding factors. In both iodine-supplemented and control ewes, serum T₃ and T₄ concentration values remained above the currently used “normal” range throughout the trial period.     

Genetic analysis of production traits in turbot (Scophthalmus maximus) using random regression models based on molecular relatedness

Reliable estimates of genetic parameters for growth traits as a trajectory of age are needed to optimize existing turbot breeding programmes. To evaluate the potential of early selection strategies, the use of biometric body measurements, length (L), width (W) and area (A), at early ages as alternative indicators for the selection trait at harvest was explored. Random regression model (RRM) based on molecular relatedness (MR) was used to analyse the trajectory of genetic parameters for growth traits in turbot from 162 to 756 days posthatch (dph). Heritability estimates for body weight (BW) ranged from 0.34 to 0.54. Heritability estimates for W, A and L were also moderate to high ranging from 0.18 to 0.43. Estimates for L and W declined with age, while those for A increased towards harvest age. Genetic (r_G) and phenotypic (r_P) correlations between BW and the three morphometric traits L, A and W were estimated using simple bivariate animal models at young (AC1), medium (AC2) and old (AC3) age classes. Correlations between BW and morphometric body traits were high, ranging from 0.7 to 0.9 in all three age groups. Genetic correlations between traits were highest (>0.9) in AC3. To explore the potential for early selection, genetic correlations were derived from the RRM between all days of measurement for all traits separately. From dph 300 onwards, intratrait estimates of r_G were moderate to high (above 0.7 for dph 410 and higher ages for traits BW, L and A). Results showed that genetic selection for BW, L and A is promising and that A and L could be successfully used as alternative indicator traits if measurements of BW are not available. Large BW and A at harvest could be achieved as a correlated response to early selection for these traits at around 500 dph.     

Genetic evaluation of growth in Barki sheep using random regression models

The objective of the current study was to estimate covariance components of growth at different ages from birth to yearling in Barki lambs. A total of 16,496 records for body weights at birth (W0), 3 (W3), 6 (W6), 9 (W9), and 12 (12) months of age for Barki lambs were available. Two statistical approaches were used; multi-trait (MT) and random regression (RR) animal models assuming two random effects only, additive genetic effect (σ²_a) and permanent environmental effect (σ²_pe) of the animal. Regarding the RR model, Legendre polynomials (LP) of different orders for the random parts were compared in order to evaluate the most appropriate model. Bayesian information and Akaike information criteria suggested that the optimal RR model included the third order for fixed effect of lamb age and σ²_pe, and fourth order of LP for σ²_a (LP₃₄₃). Estimates of direct heritability (h²_a) from LP₃₄₃ showed an ascending pattern, as it was 0.06 ± 0.03 for birth weight and reached to the peak at 9 months (0.42 ± 0.02). Thereafter, it declined again at the end of trajectory (12 months of age; 0.27 ± 0.03). The MT model showed a fluctuated pattern and lower estimates of h²_a (0.19 ± 0.03, 0.11 ± 0.02, 0.12 ± 0.02, 0.11 ± 0.03, and 0.16 ± 0.04 for W0, W3, W6, W9, and W12, respectively). Considerably, similar ascending patterns of the ratio of σ²_pe to phenotypic variance were reported from both RR (from 3 to 50%) and MT models (from 5 to 20%). Of interest, the RR model showed higher predicting ability of the breeding values compared with the MT model, which is an indicator for the suitability of RR models for analyzing the consecutive growth traits in sheep. Results suggested that the Barki sheep has a potential for genetic selection based on weight at different ages with selection likely to be more efficient at 9 months of age.

     

Effect of dimethylglycine on antibody response to influenza vaccination in horses

A double blind study evaluating the humoral response to influenza vaccination was studied in 20 age and sex matched mature horses. The horses had been immunized previously once or twice yearly but none had been vaccinated or was known to have been exposed to influenza within the preceding six months. Horses received either placebo or dimethylglycine (750 mg orally twice daily) from Days 1 through 45 and were vaccinated intramuscularly on Day 15 with a killed influenza virus vaccine containing both A₁ and A₂ serotypes. Serum hemagglutination titers were determined by 2 independent laboratories on identical serum samples drawn on Days 1, 15, and 45. No significant difference was found between the placebo and dimethylglycine treated group in the development of either A₁ or A₂ antibody titers following vaccination.     

Assessment of synovial fluid biomarkers in healthy foals and in foals with tarsocrural osteochondrosis

Although alterations in biomarkers of cartilage turnover in synovial fluid (SF) have been demonstrated in horses with osteochondrosis (OC), there have been few investigations of such alterations in animals <1 year old. In this study tarsocrural SF samples from foals aged 18, 22 and 52 weeks of age were assessed for: (1) ‘turnover’ biomarkers of type II collagen (CPII and C2C) and proteoglycan (CS846 and glycosaminoglycans [GAG]); (2) matrix metalloproteinase (MMP) activity; (3) insulin-like growth factor (IGF)-1; (4) transforming growth factor (TGF)-β1; (5) prostaglandin (PG) E₂; and (6) leukotriene B₄.Using a linear mixed model, the concentration of biomarkers was compared between animals that developed or did not develop radiographic evidence of OC at 24 or 48 weeks of age. The CPII:C2C ratio tended to be higher in OC-affected joints compared to controls at all ages, and this difference was statistically significant at 22 weeks of age. The concentrations of CS846 and IGF-1, and the CS846:GAG ratio were reduced in OC-affected joints relative to controls at 18 weeks of age only. At 52 weeks of age, the PGE₂ concentration was lower in joints with OC. Overall, there appears to be a consistent anabolic shift in type II collagen turnover in juvenile joints affected by OC. Aberrant proteoglycan turnover is not a hallmark of the late repair of this lesion but reduced concentrations of IGF-1 in SF may be associated with early-stage lesions.