| Publisher: Shahid Bahonar University of Kerman (Total: 2 journals)
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Journal of Livestock Science and Technologies
Number of Followers: 1  Open Access journalISSN (Print) 2322-3553 - ISSN (Online) 2322-374X This journal is no longer being updated because: the publisher no longer provides RSS feeds |
- Comparing genomic prediction models for genomic selection of traits with
additive and dominance genetic architecture
Abstract: ABSTRACTThe purpose of this research was to compare different statistical methods such as GBLUP, BayesA, BayesB, BayesC, BayesL, Ridge regression, Boosting and SVM for genomic evaluation of traits with additive and dominance genetic architecture. A genome consisting of 5 chromosomes was simulated, with 1000 single nucleotide polymorphism markers (SNP) uniformly distributed on each chromosome. In two different scenarios, 50 and 500 quantitative trait loci (QTL) were considered and in each scenario of QTL number, 0.00, 10, 20, 50 and 100% of QTLs were given dominance genetic effect. The prediction accuracy, bias and reliability of genomic breeding values were used for analyzing the results and comparing the methods. The results showed that not separating the dominance effects from the additive effects lead to a decrease in the accuracy and reliability and an increase in the bias of the predicted genomic breeding values. In all examined scenarios of the QTL number and percentages of QTLs with dominance effect, the Bayesian methods had higher prediction accuracy and reliability and their predictions had the least bias. Boosting predicted the genomic breeding values with the lowest accuracy and reliability and highest bias. The performance of SVM and Ridge regression was better than Boosting, but lower than Bayesian methods and GBLUP. In terms of computing speed, GBLUP and Boosting were, respectively, the fastest and the slowest method. It can be concluded that to increase the efficiency of genomic selection, first, the dominance genetic effects need to be included in the model and, second, methods with the highest predictive performance should be used.
- Effects of unprotected and calcium salts of palm and linseed oils on feed
intake, total tract digestibility, ruminal degradation and fermentation in
lambs
Abstract: The objective of present study was to assess the effects of unprotected and calcium salts of oils on total tract digestibility, ruminal degradation and fermentation in lambs. Four lambs fitted with ruminal fistula were used in a change-over design using 2 × 2 factorial arrangement. Levels of first factor (oils) were palm oil and linseed oil and levels of second factor were protected oil (calcium salts) and unprotected oil. Feeding of palm oil resulted in higher ruminal effective degradability of neutral detergent fiber (NDF) than linseed oil, and lambs fed protected oil had higher ruminal effective degradability of NDF than unprotected oil (P<0.05). Lambs fed palm oil had higher dry matter intake (DMI) and total tract digestibility of nutrients compared to those fed linseed oil. Acetate concentration in lambs fed palm oil was higher compared to linseed oil. Feeding of protected oil resulted in higher acetate concentration than unprotected oil (P<0.05). The lowest acetate concentration was found in lambs fed unprotected linseed oil (ULO) and the highest acetate concentration was observed in lambs fed unprotected and protected palm oil (UPO and PPO, respectively). Lambs fed palm oil had the highest gas and methane production compared to linseed oil. Protected oil resulted in higher gas and methane production than unprotected oil (P<0.05). Lambs fed PPO had the highest, and those fed ULO had the lowest methane production (P<0.05). Based on the results, protection of linseed oil is necessary to enhance ruminal degradation and fermentation, but this process is not necessary for palm oil.
- Fat-tailed and thin-tailed lambs responses to glucose and insulin
challenges during different energy balances
Abstract: The proportion of adipose depots varies considerably between fat-tailed (FT) and thin-tailed (TT) sheep breeds. FT breeds accumulate majority of body fat in fat-tail depot, whereas TT breeds deposit considerable proportion of body fat in visceral depots. These differences in proportion of adipose depots seem to affect body metabolism due to differences in metabolism of different depots. Hence, the current research aimed to evaluate the response of fat-tailed lambs (FTL) and thin-tailed lambs (TTL) to glucose and insulin challenges during negative energy balance (NEB) and positive energy balance (PEB). Glucose tolerance and insulin challenge tests were conducted on randomly selected lambs from each genotypes at the end of induced NEB and PEB. Glucose injection during NEB caused greater plasma glucose concentration in TTL, whereas in PEB, the enhancement in glucose concentration as a consequence of glucose injection was higher in FTL (P≤0.09). The area under the glucose curve was higher in FT compared to TT lambs during glucose tolerance test regardless of energy balance (EB; P≤0.03). The clearance rates of insulin (P≤0.09) and glucose (P≤0.006) in the respective insulin and glucose tolerance tests were higher during PEB compared to NEB regardless of the genotypes. These results demonstrated that induced NEB can enhance insulin resistance in both FT and TT lambs, severity of which is greater in FT than in TT lambs.
- Effects of different carbohydrate sources on the performance, ruminal and
blood metabolites and nutrients digestibility in fattening male-lambs fed
corn steep liquor
Abstract: The current experiment was conducted to evaluate the effects of replacing dietary corn/barley mixture with molasses, a ruminal fermentable carbohydrate source, at 0, 50 and 100 g/kg dietary dry matter (DM) in the diet of fattening lambs containing corn steep liquor (CSL, 130 g/kg DM), a ruminal degradable protein source. Twenty-four male Lori lambs (average body weight of 27.7±3.41 kg; 120.0±7.5 days of age) were randomly assigned into three groups of eight lambs each in a balanced completely randomized design. Results indicated that supplementing dietary CSL with increasing levels of molasses up to 100 g/kg DM linearly increased the digestibility of organic matter and ash-free neutral detergent fiber (P<0.05). Increasing the level of molasses in the CSL containing diets had no effect on ruminal pH (P>0.05), but linearly decreased rumen concentration of NH­­3-N (P<0.05). Except for total volatile fatty acids (VFAs) and molar proportion of butyrate which were increased linearly with increasing dietary molasses level, other VFAs were not influenced by the experimental diets. Increasing the level of molasses in the diet up to 100 g/kg DM linearly increased plasma total protein concentration while linearly reduced blood urea nitrogen concentration. Total weight gain and average daily gain were improved but feed conversion ratio decreased linearly with increasing dietary level of molasses. In conclusion, supplementing CSL with molasses at the level of 100 g/kg dietary DM increased the nutrient digestibility and performance of fattening lambs.
- Influence of LED light spectra and photoperiods on broiler breeders
production, reproduction, blood metabolites, immunological response, and
hepatic sterol regulatory element binding protein-1 (SREBP1) relative gene
expression
Abstract: Lighting is one of the important management factors affecting the health and welfare of birds. The objective of this study was to assess the effects of light-emitting diodes (LEDs) on production, reproduction, blood metabolites, immunology, and hepatic sterol regulatory element binding protein-1 (SREBP1) gene expression in broiler breeders. One-day-old Ross 308 female breeder chicks (n=100) were randomly assigned to 20 light-proof pens and reared under five lighting regimens, including green (GL) or white (WL) LED at two exposure photophases (8 or 12 hours) as a 2 ´ 2 factorial experiment plus a control group (incandescent lamp at 8L:16D duration; CON). The LED color affected the feed intake during the rearing period, being higher in white than in green light; however, green light resulted in more medium and large white follicles on the ovaries, higher mean corpuscular hemoglobin concentration, and plasma cholesterol level. In WL8 lighting, the relative weight of the bursa of Fabricius was higher (P≤0.05) than in CON birds. Plasma cholesterol level in GL12 was higher compared to CON. Conventional and WL12 regimens resulted in lower plasma alkaline phosphatase activity. Twelve hours of GL lighting resulted in higher eggshell weight and strength while it caused a small but significant decrease in egg shape index. Greater numbers of medium white (MWF) and large white (LWF) follicles were recorded in GL12 birds, and there were more small white follicles (SWF) in GL8 group (P≤0.05). The GL12 and CON lighting resulted in higher concentrations of WBC and Hb compared with WL. Hepatic expression of SREBP1 was higher in WL8 birds. The results indicated that green LED improved egg quality while white LED caused higher relative weight of bursa and hepatic SREBP1 expression, indicating the LED light may be beneficial to broiler breeder productivity. However, more studies are required to substantiate these findings.
- Phosphodiesterase inhibitor Theophylline in the aged laying hens:
investigation of the ovarian and fallopian inflammatory mediators,
hormones, and functions
Abstract: Inflammatory-dependent events in the aged commercial laying hens reduce production rate and egg quality. Our study was aimed to evaluate the phosphodiesterase (PDE) inhibitor Theophylline on the ovarian and fallopian-inflammatory traits in the commercial laying hens at the late stage of the production period. Twenty-four White Leghorn hens aged 92 weeks were used for four weeks to be orally supplemented by Theophylline (3 mg/kg/Body weight, BW). Ovulation rate and follicular growth were measured by laying frequency and, visual evaluation after euthanizing, respectively. The mRNA expressions of follicular and fallopian cyclooxygenases 1 and 2 (COX-1,-2), and cytokines were detected by real-time PCR. Plasma concentrations of ovarian hormones (Two hours after lighting) were measured via enzyme-linked immunosorbant assay (ELISA). The results showed that the mRNA expression of the IL-1β, IL-6 and TNF-α in the ovary and IL-1β and TNF-α in the infundibulum were significantly decreased (P<0.01) by Theophylline treatment; however, the mRNA abundance of COX-2 and IL-10 in both of ovary and infundibulum were increased (P<0.01). Plasma concentrations of estradiol and progesterone were elevated (P<0.05) in the hens treated with Theophylline. Ovulation rate and follicular size were not significantly (P>0.05) influenced by Theophylline. As a phosphodiesterase inhibitor, Theophylline retained the laying frequency in addition to enhancing its anti-inflammatory capability in the late stage of production period in laying hens.
- Antioxidant properties of the fennel essential oil nanoemulsion: Effect on
European production efficiency factor, blood metabolites, immune system
and cecal microbial population of heat stressed broiler chickens
Abstract: In this study, the antioxidant properties of fennel essential oil nanoemulsion (FEON) and its effect on European production efficiency factor, blood metabolites, immune system, and cecal microbial population of broiler chickens under heat stress conditions were investigated. Two hundred one-d-old Ross broiler chickens were arranged in a completely randomized design with 5 treatments, 4 replicates, and 10 birds each. The birds were fed on a basal diet (control), basal diets supplemented with 50, 100, and 200 mg kg-1 fennel essential oil nanoemulsion (FEON50, FEON100, and FEON200) and 200 mg kg-1 fennel essential oil (FEO). The results showed that compared with FEO, all concentrations of FEON had greater antioxidant activity (P≤0.001). During the starter, grower, and the whole phase of the rearing period, the performance indicators such as the European production efficiency factor and European broiler index, were not affected by dietary treatment. Further, blood total cholesterol and low-density lipoprotein contents were significantly decreased by supplementation of broiler diets with FEON (P≤0.01). Primary antibody titer against sheep red blood cells (SRBC) was affected by the addition of FEO and FEON50 into broiler diets (P≤0.05). Moreover, the Lactobacillus population of cecal content was significantly increased and coliform populations were decreased when FEON was added to the diet. The Escherichia coli population of cecal content decreased when FEO and FEON were supplemented into the diets (P≤0.05). The jejunal, ileal, and cecal digesta pH decreased significantly in the FEON50 treatment. The results of this experiment showed that under heat stress conditions, supplementation of broiler chickens' diets with FEON can enhance primary humoral immunity and improve the broiler gut health and FEON50 was the optimal level.
- The accuracy of breeding values for body size latent trait in pigs under
different prediction models
Abstract: The present study was performed to quantify a latent variable for body size (BS) from the five linear body measurements, including body length (BL), body height (BH), chest width (CW), chest girth (CG), and tube girth (TG). The study population consisted of N= 5573 Yorkshire pigs, 592 individuals out of them were genotyped using a PorcineSNP80 BeadChip. The body size latent variable was determined using Confirmatory Factor Analysis (CFA). Then, the accuracy of breeding values was obtained using pedigree-based best linear unbiased prediction (PBLUP), genomic best linear unbiased prediction (GBLUP), and single-step genomic best linear unbiased prediction (ssGBLUP) models. The overall fit indices, including standardized root mean square residual (SRMR), root mean square error of approximation (RMSEA), Tucker-Lewis Index (TLI), and comparative fit index (CFI) were obtained for the BS as 0.03, 0.09, 0.93, and 0.96, respectively which imply the adequacy of the considered model for BS construct. The performance of models was measured in a 5-fold cross-validation with 10 repeats to get a more accurate measure of the model's performance. The accuracy of models was compared via the correlation between predicted breeding values (PBV) and estimated breeding values (EBV) metric which was 0.37, 0.30, and 0.28 for PBLUP, ssGBLUP, and GBLUP, respectively. Furthermore, the goodness of fit is measured by the mean square of error (MSE) and Pearson's correlations r(y, ) between observed and predicted phenotypes. The lowest MSE and the highest Pearson's correlations were obtained under PBLUP while the highest MSE and the lowest Pearson's correlations were obtained under GBLUP. The obtained results showed the GBLUP method generally provided lower prediction accuracies than PBLUP and ssGBLUP methods, and also ssGBLUP generated lower prediction accuracy than traditional PBLUP. The performance of ssGBLUP and GBLUP was lower than expected mainly due to the small number of genotyped animals.
- Polymorphism of three ovine BMP15, INHBA and INHA candidate genes for
litter size in four Iranian Indigenous sheep using PCR-sequencing
Abstract: The inhibin α (INHA), inhibin βA (INHBA) and bone morphogenetic protein 15 (BMP-15) were investigated as candidate genes for reproductive traits in four Iranian sheep breeds (Bahmaei, Lak Ghashghaei, Lori-Bakhtiari and Karakul). Based on the ovine sequences of BMP-15, INHA and INHBA genes, three pairs of primers were designed to identify single nucleotide polymorphisms (SNPs) in exon 2 of BMP-15, INHA and INHBA in multiparous ewes by DNA sequencing. Two SNPs were detected in exon 2 of the ovine BMP15 gene at positions 367 and 430, which lead to amino acid substitutions at position 231 and 252 in the BMP15 protein sequence, respectively. Substitution of Leucine to Proline at position 252 is predicted to affect the protein function. A synonymous mutation was found in the amplified fragment of exon 2 at position 752 in ovine INHBA gene. In addition, the c752C>T mutation was only found in heterozygous condition in only one Lori-Bakhtiari ewe, while other breeds were in wild type genotype for c752C>T mutation. The INHA gene was shown to be highly polymorphic. A total of 7 SNPs including 6 nucleotide substitutions and one insertion were found in the amplified fragment of the INHA locus. The insertion mutation was found in two animals of Bahmaei and Karakul breeds. Interestingly, homozygous condition for the mutant alleles in all identified SNPs in BMP15, INHA and INHBA loci was absent in these breeds. Generally, these breeds showed different genetic structures with regard to the identified SNPs in BMP15, INHBA and INHA genes. However, further research with larger sample size and phenotype data on reproductive performance is required to investigate the definitive effect of the identified mutations in this study.
- Performance response of neonatal calves to milk enriched with organic iron
Abstract: The current study aimed to investigate the effects of different sources of organic iron (native product in comparison to foreign ones) in the milk on plasma mineral concentration (Fe, Cu, Ca, P, and Zn), body weight, starter intake, feed conversion ratio (FCR), health condition, body measurements, and fecal score. Female calves (n=36) were randomly allocated to 3 groups (12 calves per treatment) and fed control milk (no iron supplement) (C), a low dose of iron (LF) consisting of 400 mg of Fe supplementation with the purity of 10% iron (native) and high dose of iron (HF) which had 200 mg of Fe supplementation with 20% purity (foreign). All animals were kept in individual pens and had ad libitum access to starter feed and water during the experimental period. From the first day of age to weaning (56 days), starter intake was measured daily. Body weight, skeletal measurements, fecal score, and health parameters were monitored weekly until weaning age. Calves that received the iron supplements had higher plasma Fe concentration, average daily gain (ADG) and starter intake, in contrast, they had low Cu, Ca, and P content and FCR than the control group. Supplementing milk with iron resulted in improved health status. Results showed that native Fe had the same impacts as the foreign product. There were no notable effects of treatment on skeletal parameters, fecal score, heart rate, respiratory rate, and rectal temperature. According to this experiment, applying iron supplements in diets requires taking into account the iron supply via other sources such as milk and or solid feeds. According to this experiment, although calves’ health and performance improved regardless of iron sources, the amount of iron supplied through other sources such as milk or solid feed should also be considered, when using iron supplements in the diet.
- Evaluation of the estrus synchronization and reproductive performance of
Afshari ewes during the breeding season following treatment with
clomiphene citrate
Abstract: The present study was conducted to study the efficiency of substituting conventional gonadotropin-based technique with clomiphene citrate (CC) on reproductive parameters and hormonal changes in sheep during the breeding season. For this this purpose, 30 Afshari ewes (3-4 years, 55 ± 1.3 kg BW, BCS 3.04±0.3) were treated with intravaginal CIDR for 14 days and the divided into three groups: one group was considered as the control, the other groups received eCG (300 IU, intramuscularly) and CC (600 mg, oral), respectively. Blood samples were taken from three days before until three days after CIDR removal. Reproductive parameters were calculated after parturition. Fecundity and multiple lambing were numerically higher in the eCG group; however, there was no significant difference in reproductive performance between treatments. Estradiol and progesterone concentrations showed similar trends between treatments. Results of this study showed that CC was not a reliable substitute for eCG to increase the ovulation rate in sheep.
- A meta-analysis study of the association between FecB polymorphism and
litter size in sheep
Abstract: In the current study, a meta-analysis was carried out by merging outcomes resulting from 26 published studies in various breeds of sheep to assess the influence of the FecB gene on litter size by applying the additive, recessive, dominant, and co-dominant genetic models. The model with random effects was used for data analysis according to the Cochran Q test and I2 quantity statistical measures. Standardized mean difference (SMD) was applied to measure the size effects of ' +' and B alleles of FecB on the litter size. The significant effect (P<0.01) of FecB genotypes on the litter size was identified under the additive (SMD = 0.511), dominant (SMD = 0.469) and recessive (SMD = 0.255) models. An increase in the litter size by approximately 0.47 lambs (Dominant model) was associated with the first copy of the FecB gene and 0.25 lambs (Recessive model) with the second copy of FecB. The findings of the current study supported the idea that BMPR1B would fundamentally influence the litter size in sheep. Subsequently, it may be utilized in marker-assisted selection programs to improve the genetic merit of litter size in the future. Introgression this gene through crossbreeding programs in low prolific breeds may improve reproductive performance.
- In ovo and dietary feeding of betaine to broiler chickens under heat
stress conditions: Effects on hatchability, performance, body temperature
and blood parameters
Abstract: The effects of in ovo feeding (0 and 1g/L) and dietary feeding (0 and 1g/kg diet) of betaine on hatchability, performance, body temperature and blood parameters of broiler chicks under heat stress condition, were investigated using 600 fertile eggs (Ross 308) for in ovo injection at 17.5d of incubation. After hatching, 192 male chickens were divided into four groups: 1- In ovo feeding of non-betaine solution and post-hatch diet without betaine, 2- In ovo feeding of non-betaine solution and post-hatch dietary feeding 1g per kg of betaine, 3- In ovo feeding of 1g per L betaine solution and post-hatch diet without betaine, and 4- In ovo feeding of 1g per L betaine solution and post-hatch dietary feeding 1g per kg of betaine. The chicks were exposed to heat stress from 7-28d for 4h/d. The results showed that body weight of hatched chicks and the hatched chick body weight to initial egg weight ratio, was significantly increased by in ovo feeding of betaine (P<0.05). The effects of in ovo feeding and dietary feeding of betaine resulted in higher feed intake (P<0.05) and daily weight gain (P<0.01) and improved feed conversion ratio (P<0.05) for 7-21d. Birds that received dietary betaine had more carcass, breast and leg weight than chickens receiving betaine-free diet at 28d (P<0.05). The experimental treatments had no significant effect on carcass yield at d 42. During heat stress between 14 and 21d age, the group that did not receive betaine (in ovo or dietary) had the highest cloacal temperature (P<0.01). The concentration of high-density lipoproteins, triglycerides and cholesterol in the blood of chickens that received betaine-free diet was significantly higher than other groups (P<0.05). In general, dietary betaine feeding improved the performance and carcass parameters and decreased blood lipids and cloacal temperature of chicks under heat stress conditions. However, these effects were not observed from days 28 to 42, which were free of heat stress.
- Effect of hydrolyzed and live yeast supplementation during transition
period on colostrum and milk composition and blood biochemical parameters
in dairy cows
Abstract: The main purpose of this study was to assess live yeast and hydrolyzed yeast effects on blood biochemical parameters, colostrum quality and performance of dairy cows during transition period. Fifteen pregnant Holstein dairy cows were randomly divided into three groups during three weeks pre- and post-parturition. Cows were assigned to treatments as: 1) control group fed basal diet, 2) cows fed basal diet plus 6.0 g/d/head live yeast and 3) cows fed basal diet plus 20 g/d/head hydrolyzed yeast as on top. Live yeast supplementation resulted in higher dry matter intake and milk production compared with hydrolyzed yeast and the control group. Cows received live yeast had the highest milk fat percentage and those in the control group had the lowest lactate dehydrogenase and alkaline phosphatase activities and those received hydrolyzed yeast had the highest IgG and lactoferrin in the colostrum. Cows received live yeast had the highest serum albumin and those in the control group had the lowest serum albumin. Cows received hydrolyzed yeast had the highest globulin among treatments. There was no difference among treatments for blood triglyceride, cholesterol, non-esterified fatty acids and beta-hydroxy butyric acid. Cows in the control group had the highest aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase activities in the serum. Live yeast and hydrolyzed yeast supplementation reduced aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase in the serum. Cows receive hydrolyzed yeast had higher IgG level in the serum. Dietary supplementation of live yeast could improve feed intake and milk yield post parturition, but hydrolyzed yeast enhance immunity components of colostrum. Pre-parturition, supplementation of 20 g/d/head hydrolyzed yeast in the diet of dairy cows recommended for enhancing immunity status of cow and her newborn and post-parturition, supplementation of 6.0 g/d/head live yeast recommended for better production performance.
- Nutritional value of barley, triticale and oat grain varieties based on in
vitro gas production and fermentation parameters, and Cornell Net
Carbohydrate and Protein System
Abstract: This research was conducted to evaluate the nutritional value of different varieties of barley (Turkmen, Reyhan and Gorgan), triticale (Juvanilo, Rondo and Massa) and oat (Wild and Canadian) grains. The chemical composition of the samples was determined using the standard methods of AOAC. Gas production (GP) test was performed to estimate the in vitro fermentation parameters. In vitro digestibility was determined by the batch culture procedure. The carbohydrate fractions of the Cornell Net Carbohydrate and Protein System (CNCPS) were also measured. Crude protein (CP) content was more in triticale and barley than oat grains (P<0.01). Triticale grains had higher contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), and lower lignin compared to barley and oat grains (P<0.01). The amounts of GP potential and fermentation parameters were higher in triticale and barley than oat grains (P<0.01). Partitioning factor (PF, P<0.01), microbial biomass (MB, P<0.05) and efficiency of microbial biomass (EMB P<0.01) were more in different varieties of triticale and barley than oat varieties. According to CNCPS, carbohydrate portions and total carbohydrate content in triticale and barley grains were higher than in oat grains (P<0.01). The highest and lowest contents of none- fiber carbohydrates (NFC), starch, and soluble sugars were observed in triticale and oat varieties, respectively. Totally, triticale and barley grains had a better nutritional value than oat grains. Triticale grains were as good as barley grains in most aspects, while being superior in some traits.
- Determination of apparent and true ileal digestibility of calcium in
limestone with different particle sizes in broilers and pullets
Abstract: A feeding experiment was performed to determine the effect of limestone particle size on apparent (AIDC) and true (TIDC) ileal digestibility coefficients of calcium (Ca) in broilers and pullets. With this motivation, four dietary treatments were developed based on a 2×2 factorial arrangement, that included two limestone particle sizes (fine vs. coarse) and two bird types (broilers vs. pullets). Each treatment was replicated six times (eight birds/replicate). Two corn-based diets containing limestone with either fine (<0.5 mm) or coarse (1-2 mm) particles as the sole Ca source were developed and fed to broilers and pullets from 16 to 20 days of age. A Ca-unsupplemented diet was used to determine the ileal endogenous Ca losses. Titanium dioxide was incorporated in all diets as an indigestible marker. Digesta were collected on day 20 from all birds per pen. The AIDC of Ca was determined by marker and the TIDC values were determined by correcting for endogenous Ca losses. Endogenous Ca losses were obtained to be 420 and 696 mg/kg of dry matter intake for broilers and pullets, respectively. Broilers consumed more feed (P=0.001) and had higher body weight gain (P<0.05) than the pullets. Broilers had higher AIDC and TIDC of Ca than pullets (P<0.001). Coarse limestone particles increased the AIDC and TIDC of Ca regardless of bird type. Feeding coarse limestone increased the Ca concentration in the gizzard content of broilers but not in pullets, resulting in a significant (P<0.05) interaction between limestone particle size and bird type. Regardless of bird type, increasing limestone particle size enhanced AIDC and TIDC of Ca in limestone.
