Peripheral leucocyte molecular indicators of inflammation and oxidative stress are altered in dairy cows with embryonic loss.

Objective of experiment was to determine whether oxidative stress (OS) and inflammation altered embryonic loss in dairy cows. Blood samples were collected at days 0, 16, 32 and 60 after timed (AI) from 200 Holstein cows to determine embryonic loss based on interferon-stimulated gene-15 (ISG15) mRNA expression (day 16) and ultrasound at day 32 and day 60. Leucocyte expressions of mRNA TLR2, TLR4, TNF-α, IL1B, IL10, STAT3 (inflammation), PTGS2, PTGES (prostaglandin synthesis), and PLA2G4A and ALOX5AP (eicosanoid metabolism) at days 0 and 16 were determined. Plasma redox status for antioxidant enzymatic activities of glutathione peroxidase (GPX), superoxide dismutase (SOD), total antioxidant capacity (TAC), and concentrations of malondialdehyde (MDA) were determined at days 0, 16, 32 and 60. All antioxidant-redox responses were beneficially significant in pregnant cows diagnosed pregnant at day16 and sustained pregnancy to day 60 compared to non-pregnant cows at day16 or pregnant at day16 and lost embryos by days 32 or 60. The leucocyte mRNA expressions of TLR2, TLR4, STAT 3, IL1B, PTGS2, PLA2G4A and ALOX5AP were greater and PTGES was lower at day16 in pregnant cows that lost embryos early (P < 0.05). In conclusion peripheral leucocyte molecular indicators of inflammation and plasma indicators of OS were altered in pregnant cows undergoing embryonic losses compared to cows with a sustained pregnancy.

Reproductive performance, expression of TRAP6 and TGF-ß4 genes in utero-vaginal junction mucosa, and indicators of liver function in female Chukar partridge (Alectoris chukar) breeders fed with fish oil and calcitriol during the egg-laying period.

Reproductive attributes, expression of TRAP6 and TGF-ß mRNA in the mucosa of the utero-vaginal junction (UVJ) of oviduct, and liver function were evaluated in Chukar partridge (Alectoris chukar) breeders subjected to long-term oral administration of fish oil (FO) and/or calcitriol (CT). A total of forty-eight 1.5-year-old laying Chukar partridges and 16 age-matched males (female:male ratio of 3:1) were randomly allocated to four groups (4 replicates of 3 female birds and one male bird each). Breeder females in groups 1, 2, and 3 were orally administered daily with 0.2 mL (0.24 g)/500 g body weight FO, 0.2 mL solution containing 10 µg CT, or their combination (FO + CT) for 42 successive days, respectively. Pure crystalline calcitriol was dissolved in ethanol (30%) prior to administration. The control group (CON), received a similar volume of a 30% solution of ethanol only. Eggs were collected and incubated to evaluate the reproductive performance. Blood samples were taken on days 0, 21, and 42 of the trial for the quantification of serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). On day 43, one bird per replicate was killed by cervical dislocation to assess the expression of TRAP6 and TGF-ß genes in the UVJ mucosa. Administration of CT or FO + CT increased the egg production rate, fertility rate, and hatchability rate of the set eggs. Fertility duration and sperm penetration rate were higher in partridges receiving FO and (or) CT, but chick quality, and embryonic mortality were not affected by the treatment effect. Administration of CT or FO + CT decreased the serum ALT and AST levels. Administration of FO or CT was associated with a lower expression of TGF-ß mRNA in the UVJ mucosa. Oral administration of FO resulted in a reduction in the expression of TRAP6 in the UVJ mucosa. However, the birds fed with CT or FO + CT recorded a higher mRNA expression for TRAP6. Although the reproductive performance and TRAP6 expression were higher following the feeding of FO or FO + CT, expression of TGF-ß was decreased, suggesting plausibly that TGF-ß may not have a determinant effect on the reproductive attributes in female Chukar partridges. Further studies are required to understand the mechanisms underlying the effects of TRAP6 and TGF-ß on other reproductive criteria in partridges.

Effects in broiler hens of genetic lines differing in fertility, biotin supplementation, and age on relative abundance of oviductal transforming growth factor-ß and carbonic anhydrase mRNA transcripts.

There was evaluation of effects of biotin administration on oviductal abundance of transforming growth factor-ß (TGF-ß) and carbonic anhydrase (CA) mRNA transcript in younger and older broiler hens of relatively lesser and greater fertility lines. Additionally, effects of biotin supplementation on attenuation of age-related subfertility were evaluated. Hens from the relatively greater (Line D, n = 60) and lesser (Line B, n = 60) fertility rate line were randomly assigned to three treatment groups. Biotin was not or was administered in drinking water from 30 to 33 (younger age) and 53 to 56 (older age) wk of age to have access to no biotin (T0), or 0.3 (T1), or 0.45 (T2) mg/L of biotin. There was assessment the relative oviductal abundances of TGF-ß and CA mRNA transcript abundances. Supplemental biotin and age had no effect on the relative abundance of oviductal TGF-ß mRNA transcript in hens of Line D. There, however, was a ten-fold greater abundance of TGF-ß in hens of the T0 group of Line B compared with Line D. Relative abundance of TGF-ß mRNA transcript was greater in younger hens of Line B; however, biotin supplementation of older hens of the T2 group of Line B resulted in a similar TGF-ß abundance to that of younger hens. Inconstant with the TGF-ß abundance, CA abundance in hens of Line B was not affected by supplemental biotin or bird age. Overall, differences in TGF-ß or CA abundances did not affect fertility of broiler hens.

Postpartum health disorders in lactating dairy cows and its associations with reproductive responses and pregnancy status after first timed-AI.

The objective was to evaluate the association between postpartum health disorders, reproductive responses and pregnancy status in lactating multiparous cyclic Holstein cows. Cows were retrospectively categorized as healthy (n = 70) or sick (n = 60) based on postpartum health records and serum metabolites. Sick cows were further categorized as having metabolic (MET; n = 35), infectious (INF; n = 15), or both diseases (MET/INF; n = 10). Blood samples were collected on d 7 and 14 after calving to determine serum concentrations non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB) and aspartate aminotransferase (AST), on d 0 (TAI), 8, 16, 18 and 20 after TAI to determine concentrations of progesterone (P4; d 0, 8, 16, 18 and 20) and prostaglandin F metabolite (PGFM; d 16, 18 and 20) and interferon-stimulated gene-15 (ISG15; d 16) relative mRNA expression. Cyclicity was determined by transrectal ultrasonography 30 d postpartum and cows were subjected to a GnRH-based TAI protocol (to classify cows bearing a visible CL as cyclic). Prediction of pregnancy status on d 16 after TAI was determined by ISG15 mRNA gene expression relative to ß actin and following, pregnancy was diagnosed by transrectal ultrasonography at 32 and 60 d after TAI. An interaction (P = 0.04) between occurrence of disease and pregnancy status was detected for the expression of ISG15 in blood, with healthy pregnant healthy cows having the greatest relative expression of ISG15. Postpartum health disorders were associated with reduced concentration (P < 0.05) of serum P4 post TAI. However, serum P4 concentrations at TAI were greater (P = 0.01) in sick cows (0.65 ±â€¯0.09, 0.86 ±â€¯0.13 and 0.75 ±â€¯0.10 ng/mL for MET, INF and MET/INF cows, respectively) compared with that in healthy cows (0.24 ±â€¯0.10 ng/mL). Serum concentrations of PGFM after TAI was reduced in healthy cows, regardless of pregnancy status. Pregnancy status on d 16 after TAI predicted by ISG15 mRNA expression and P/AI on d 32 and 60 after TAI based on ultrasonography, were negatively affected (P < 0.05) by occurrence of health disorders. Similarly, pregnancy loss from d 16 to 32 and d 16 to 60 after TAI was greater (P < 0.05) in sick cows compared to that in healthy cows. However, neither P/AI nor pregnancy loss were associated to the category of postpartum health disorder. Cows affected by postpartum health disorders had overall reduced P4 and greater PGFM serum concentrations after TAI, which were associated with reduced pregnancy success and enhanced pregnancy loss. Collectively, our findings support the hypothesis of a carryover effect of disease on reproductive responses, embryo survival and maintenance of pregnancy in lactating dairy cows independent of the category of postpartum health disorder.

Effects of dietary curcumin supplementation on seminal quality indices and fertility rate in broiler breeder roosters.

1. Decreased semen quality is an underlying contributor to age-related subfertility in broiler breeder roosters. This study investigated the effects of dietary curcumin (derived from turmeric) supplementation as an antioxidant source on semen quality and fertility in broiler breeder roosters. 2. Twenty-eight Ross 308 roosters were randomly allotted to four groups with seven birds in each and were fed a standard diet supplemented with different levels of curcumin at 0 (C0), 10 (C10), 20 (C20) and 30 (C30) mg/bird per day from 48 through to 61 weeks of age. Body weight and semen quality traits were evaluated on a weekly basis and seminal concentrations of malondialdehyde (MDA) as a measure of antioxidation status were quantified at one-week intervals during the first 11 weeks of the trial (48-59 weeks of age). Semen samples from last 2 weeks (60 and 61 weeks of age) were used to artificially inseminate to assess the sperm-egg penetration (SP) in perivitelline membrane and fertility rates. 3. Except for body weight and ejaculate volume, other characteristics, including semen concentration, total sperm production, progressive motility and plasma membrane integrity were linearly improved by the increasing levels of curcumin supplementation (P < 0.01). However, dietary curcumin levels were linearly and quadratically associated with decreased seminal concentration of MDA (P < 0.01 and P < 0.03), percentage of abnormal sperm (P < 0.01 and P < 0.07) and increased plasma membrane functionality (P < 0.01 and P < 0.04), respectively. The SP holes in perivitelline membrane were increased in a linear and quadratic manner in response to increasing levels of curcumin (P < 0.01). Moreover, fertility rate was linearly improved (P < 0.01) as the dosage of curcumin increased, and resulted in 8, 12 and 14% improvements in the birds fed C10, C20 and C30, compared to C0, respectively. 4. In conclusion, the results showed that increasing levels of dietary supplementation of curcumin was associated with beneficial effects on semen quality indices and fertility rate in aged broiler breeder roosters.

TGF-ß4 and HSP70 responses in breeder hens treated with thyroxine.

A hypothesis was tested that long-term administration of thyroxine (T4) in broiler breeder hens would affect fertility, sperm penetration rate, and the duration of fertility. Relative abundance of oviductal TGF-ß4 and HSP70 mRNA was determined to ascertain whether T4 treatment affected these genes, and modulated the sustained storage of spermatozoa within the uterovaginal sperm storage tubules of hens. A total of 70, 47-week-old Cobb 500 breeder hens was randomly allotted to two treatment groups (T4 treatment (ET) and control). The T4 was orally administered to the ET group (0.3 mg T4/bird/day) for 100 consecutive days; whereas the control group was not administered T4 during the experimental period. Breeder hens were artificially inseminated to evaluate specific reproductive variables. On the last day of the treatment period two hens /replicate were randomly killed to estimate oviductal gene expression. The T4 treatment resulted in an increase in plasma concentration of T4; however, the T3 concentration was not affected. The long term administration of T4 had no effect on fertility; however, it resulted in a decreased sperm penetration rate and decreased the duration of fertility compared with the control group. The relative abundance of TGF-ß4 and HSP70 mRNA in the SST was not influenced by T4 supplementation. The correlation coefficients between fertility and sperm penetration rate with relative abundance of TGF-ß4 and HSP70 were not significant. Overall, among the diverse reproductive variable assessed in the current study, the sperm penetration rate and the duration of fertility were most responsive to long-term treatment with T4.

Modifications of the G6G timed-AI protocol improved pregnancy per AI and reduced pregnancy loss in lactating dairy cows.

In dairy cows, subjected to a G6G protocol, objectives were to determine effects of (1) extending the interval from prostaglandin F2α (PGF2α) to gonadotropin-releasing hormone (GnRH) during presynchronization; and (2) adding a second PGF2α treatment before artificial insemination (AI), on ovarian response, plasma progesterone (P4) concentrations and pregnancy per AI (P/AI). In a 2×2 factorial design, lactating cows were randomly assigned to one of four timed AI (TAI) protocols: (1) G6G (n=149), one injection of PGF2α, GnRH 2 days later and a 7-day Ovsynch (GnRH, 7 days, PGF2α, 56 h, GnRH, 16 h, TAI) was initiated 6 days later; (2) G6GP (n=144), an additional PGF2α treatment (24 h after the first) during Ovsynch of the G6G protocol; (3) MG6G, one injection of PGF2α, GnRH 4 days later before initiation of the G6G protocol; and (4) MG6GP, an additional PGF2α treatment (24 h after the first) during Ovsynch of the MG6G protocol. Blood samples were collected (subset of 200 cows) at first GnRH and PGF2α of the Ovsynch, and at TAI to measure P4. Ultrasound examinations were performed in a subset of 406 cows to evaluate ovarian response at various times of Ovsynch, and in all cattle to determine pregnancy status at 32 and 60 days after TAI. Extending the interval by 2 days between PGF2α and GnRH during presynchronization increased (P<0.01) ovulatory response to first GnRH of Ovsynch, circulating P4 during Ovsynch, and P/AI at 32 and 60 days after TAI. Adding a second PGF2α treatment before AI increased the proportion of cows with luteal regression (P=0.04), improved P/AI at 60 days after TAI (P=0.05), and reduced pregnancy loss between 30 and 60 days after TAI (P=0.04). In summary, extending the interval from PGF2α to GnRH during presynchronization increased response to first GnRH of Ovsynch and P4 concentrations during Ovsynch, whereas adding a second PGF2α treatment before AI enhanced luteal regression. Both modifications of the G6G protocol improved fertility in lactating dairy cows.

Dietary conjugated linoleic acid supplementation alters the expression of genes involved in the endocannabinoid system in the bovine endometrium and increases plasma progesterone concentrations.

Endocannabinoids are derived from phospholipids and reduce fertility by interfering with implantation. Identification of changes in the expression of genes of the endocannabinoid system as a result of dietary inclusion of conjugated linoleic acid (CLA) is critical to the advancement of our understanding of the nutritional regulation of uterine function. An experiment was conducted on transition cows to evaluate the expression of key endocannabinoid genes in bovine endometrium in response to dietary supplementation with CLA. A total of 16 cows were randomly assigned to two treatments: (1) control (75 g/day palm oil) and (2) CLA (75 g/day CLA) from 21 days prepartum to Day 42 postpartum. Cows underwent uterine biopsy on days 21 and 42 postpartum. The abundance of mRNA encoding endocannabinoid receptor (CNR2), N-acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N-acylethanolamine acid amidase (NAAA), and monoglyceride lipase (MGLL) was measured by real-time PCR. Results reported that relative levels of mRNA encoding CNR2 and NAPEPLD were decreased (P < 0.05) compared with control cows between Days 21 and 42 postpartum. Relative levels of mRNA coding for NAAA and MGLL were not different (P > 0.05) in the same situation. Mean plasma progesterone concentrations were higher in CLA-fed cows compared with control cows at Day 42 postpartum (3.51 and 1.42 ng/mL, respectively, P < 0.05). In conclusion, we suggest that the beneficial effects of a diet enriched with CLA are the result of a decrease in relative gene expression of the endocannabinoid receptor (CNR2) and enzymes that synthesize fatty acid amides (NAPEPLD) and of an increase in the expression of PTGS2 that in turn can oxidate endocannabinoids and consequently resulted in increased plasma progesterone concentrations during early lactation.

The effect of feeding excess arginine on lipogenic gene expression and growth performance in broilers.

1. Reducing excess fat accretion is important for both human health and animal production. The present study was conducted to investigate the effects of arginine (Arg) on the regulation of lipogenic gene expression and on growth performance. 2. One-d-old female broiler chicks (Ross, n = 192) were used in a completely randomised design with 4 dietary treatments in which diets included 100% (CTL), 153% (LArg), 168% (MArg) and 183% (HArg) of the recommended concentration of digestible Arg. 3. Results showed that high concentrations of Arg improved body weight gain, feed efficiency, meat production, fat and crude protein content of breast muscle and plasma thyroid hormones. Conversely, abdominal fat, cholesterol, triglyceride and urea were lower with higher concentrations of Arg. Dietary arginine increased lipogenic gene expression in muscles, while decreasing those in adipose tissue and liver. 4. It was concluded that increasing Arg in the diet reduced abdominal fat content, enhanced intramuscular fat and increased muscle and protein gain. Furthermore, Arg supplementation at the MArg concentration improved growth performance, and at HArg had the greatest effect on fat reduction.

Changes in some blood parameters and production performance of old laying hens due to growth hormone and testosterone injection.

The experiment was designed to study the changes in some blood parameters and production performance of old laying hens after injection of different doses of growth hormone (GH) and testosterone (Ts). A total of 160 old laying hens (HyLine W-36) at 73 weeks of age were weighed individually and randomly allocated to four treatments with four replicates and 10 birds in each replicate in a completely randomized design. Growth hormone and Ts hormones were injected subcutaneously. Treatment groups were as follows: treatment 1: injection of 100 µl distiled water (control group), treatment 2: injection of 500 µg Ts/kg live-weight + 50 µgGH/kg live-weight, treatment 3: injection of 500 µgTs/kg live-weight + 100 µgGH/kg live-weight and treatment 4: injection of 500 µgTs/kg live-weight + 150 µgGH/kg live-weight. Plasma levels of oestradiol, T4 , LDL, HDL and cholesterol significantly increased in treatment 3 in relation to the control group. All injected hens showed significantly higher levels of glucose in relation to control group. The results showed the positive effects of GH and Ts administration on production performance and blood parameters which are associated with egg production potentiality and in turn may improve reproductivity (egg production) in old laying hens. The positive results of the study may be useful in animal selection and breeding programmes.

Prestorage in ovo injection of biological buffers: an approach to improve hatchability in long-term stored eggs.

A hypothesis was tested that the in ovo injection of biological buffers may reinforce the buffering capacity of albumen, thereby withstanding the increase in albumen pH during storage and improving hatchability and chick quality in long-term stored eggs. Hatching eggs (n = 2,420) were randomly assigned to 11 treatment groups (4 replicates of 55 eggs each) and injected (d 1) with distilled water, 25 or 50 mM HEPES (H25 and H50), Bicine (B25 and B50), Tris (T25 and T50), and Bis-Tris-propane (BTP25 and BTP50) solutions or were not injected (intact: control; or pricked with a needle: N). The eggs were then stored for 14 d during which the egg internal characteristics were evaluated at 1, 2, 3, 4, 5, 8, and 13 d of storage (n = 924 in total) and the remaining eggs (n = 1,496) were incubated. A decrease in albumen pH was found for H25, H50, B50, and BTP25 groups from 2 through 5 d postinjection. Eggs receiving H25, H50, and B50 recorded a higher albumen index (at 13 d of storage) and Haugh unit (between 8 and 13 d of storage) compared with the control. Interestingly, the hatchability of fertile eggs was influenced by the treatment effect (P = 0.0001) where the eggs receiving H25 (88.3%), H50 (88.9%), B50 (88.4%), and BTP25 (87.6%) recorded higher values than that of control (82.1%), associated with a decreased early embryonic mortality rate (P < 0.0001). In ovo injection of Tris buffer, however, profoundly decreased the hatchability (47.2 and 29.0% for T25 and T50, respectively) and percentage of first-grade chicks (67.5 and 63.6% for T25 and T50, respectively) compared with the control (90.1%). In conclusion, prestorage in ovo injection of H25, H50, B50, and BTP25 improved hatchability in long-term stored eggs in which a decreased albumen pH during the d 2 through 5 of storage period might be involved.

Oral exposure of broiler breeder hens to extra thyroxine modulates early adaptive immune responses in progeny chicks.

Based on the findings of a recent study suggesting a decreased cold-induced ascites incidence in broiler progeny from hyperthyroid (HYPER) breeder hens, and a controversy on the effects of hyperthyroidism on immunocompetence, the present study was conducted to determine the probable adverse effect of induced maternal hyperthyroidism on immune function in progeny chicks. Breeder hens (n = 88) were randomly allotted to the control or HYPER groups and received common or thyroxine (T4)-added (1 mg/L) water, respectively. The hens were artificially inseminated, and hatching eggs (n = 924) were incubated. Thereafter, the male hatchlings (n = 288) were reared for 42 d, and several cellular and humoral immune responses were evaluated at standard or low ambient temperature. Prevaccination antibody titers to Newcastle disease, infectious bronchitis, and infectious bursal disease virus were higher in HYPER chicks during 1 wk of age, although not different in their dams. For primary response to SRBC administered at 7 d of age, HYPER chicks recorded higher total, IgM (d 14), and IgG (d 21) anti-SRBC antibody titers. Higher cutaneous basophilic hypersensitivity response in HYPER chicks (d 10) was not observed at 35 d of age. Carbon clearance assay showed no difference, but in vitro lymphoproliferative response to concanavalin A was higher in 19-d-old HYPER chicks, independent of temperature treatment. An increase in lymphocyte percentage coincided with a decreased heterophil percentage and heterophil to lymphocyte ratio (d 14) in the HYPER group. The weight of lymphoid organs in progeny was not influenced by the oral exposure of dams to extra T4. Independent of T4 treatment, cold exposure was generally associated with decreased immune functions at early stages. The data suggested that oral exposure of broiler breeder hens to 1 mg/L of T4 not only had no adverse effect on immune function, but also modulated early adaptive immune responses in progeny chicks for which the causal mechanisms remain to be unraveled.

Effects of different polyunsaturated fatty acid supplementations during the postpartum periods of early lactating dairy cows on milk yield, metabolic responses, and reproductive performances.

In spite of the difficulties in delivering PUFA to ruminants, studies have generally indicated that the PUFA of the omega-6 (linoleic acid) and omega-3 [α-linolenic acid; eicosapentaenoic (EPA), C20:5 omega-3; docosahexaenoic (DHA), C22:6 omega-3] families are the most beneficial to improving reproduction in cows. The objectives were to determine if a diet enriched in α-linolenic acid (omega-3) or linoleic acid (omega-6) would influence milk production and composition, metabolic status, and reproductive performance in lactating dairy cows. High-yielding multiparous Holstein dairy cows (n = 120) with no overt clinical illnesses were blocked according to calving date and parity. Cows were assigned randomly to be fed 1) soybean whole roast (Soy, omega-6, n = 40) or 2) linseed (Lin, omega-3, n = 40) or 3) palm oil as a source of SFA (PO, n = 40) from calving until first heat after 40 d postpartum (dpp), and then half of the cows in each treatment group were switched to receive either Lin or SFA (PO) from first heat after d 40 to 120 dpp. Blood was collected from a subsample of cows. Blood was collected at 14 d intervals for 12 wk, starting on the day of calving. Results showed milk yield and DMI were not affected. Milk compositions were similar (P > 0.08) among diets, except concentration and yield of milk fat percentage, which was less in cows fed Lin (P < 0.05). Uterine involution in cows fed Soy occurred earlier (P < 0.05). Diets affected day to first estrus and day to first insemination in cows (P < 0.05). There were no differences among treatments for percent heat detection, percent pregnancy per first insemination, and percent conception per AI at estrus. Also, there is a trend of pregnancy by 120 d, which is 66.7% for the Lin group vs. 50.91% for the PO group (P < 0.08). Of the 4 pregnancy losses, 2 occurred in PO-PO group and 2 occurred in Soy-PO group, and none occurred in the other 4 treatments. In conclusion, our study showed feeding omega-6 fatty acids during 40 dpp could be a good treatment for early postpartum periods, and a shift to omega-3 fatty acids until 40 d after AI can be considered as a strategy for improving fertility in lactating dairy cows.

Maternal hyperthyroidism is associated with a decreased incidence of cold-induced ascites in broiler chickens.

A hypothesis was tested that providing the breeder hens with exogenous thyroxine (T(4)) would help their offspring to better survive the ascites-inducing condition during the growing period. In total, 132 broiler breeder hens were randomly assigned to one of 3 treatments: control (CON), hypothyroid [HYPO; 6-N-propyl-2-thiouracil (PTU)-treated], and hyperthyroid (HYPER; T(4)-treated). The hens were artificially inseminated, and the hatching eggs (n = 1,320) were incubated. No eggs in the HYPO group hatched. The 1-d-old male chicks (n = 288) from other groups were reared for 42 d under standard or low ambient temperature to induce ascites. Blood samples were drawn from the hens, embryos, and broilers for determination of T(4) and triiodothyronine (T(3)). The hematocrit was also determined in broilers. The PTU-treated hens had an increased BW along with lower plasma T(3) and T(4) concentrations. Plasma T(4) was higher in the HYPER hens compared with CON hens, but T(3) concentration was not different between these groups. The fertility rate was not affected by either hypo- or hyperthyroidism. The embryos in the HYPO group had lower plasma T(3) and T(4) concentrations at d 18 of embryonic development and internal pipping. Higher plasma T(4) was recorded in the HYPER birds at internal pipping, although plasma T(3) concentration was not affected at this stage. Maternal hyperthyroidism decreased the overall incidence of ascites in the cold-exposed chickens (10.0 vs. 33.4% for HYPER and CON groups, respectively). Although the effect of maternal PTU or T(4) treatment on plasma thyroid hormones and on the right ventricle-to-total ventricular weight ratio in the broilers was not significant, the cold-exposed healthy CON chicks showed higher hematocrit values, compared with the HYPER birds. It was concluded that maternal hyperthyroidism could decrease the incidence of cold-induced ascites in broiler chickens; however, probable causal mechanisms remain to be elucidated.

High- and low-temperature manipulation during late incubation: effects on embryonic development, the hatching process, and metabolism in broilers.

Temperatures continuously higher and lower than the standard incubation temperature by 3°C from embryonic d 16 until embryonic d 18.5 result in differential effects on embryonic development, the hatching process, and embryonic metabolism. Embryos in the high-temperature group were forced into a state of malnutrition by the temperature treatment, as reflected by reduced embryo growth and yolk consumption, resulting in a significantly lower chick weight at hatch. In addition, altered air cell and blood gases as well as a retarded hatching process further indicated reduced growth of embryos exposed to higher incubation temperatures during the latter part of incubation. In addition, hatchability was significantly reduced by the high-temperature treatment due to higher embryonic mortality during the treatment period and the hatching process. Levels of blood glucose, lactate, liver glycogen, plasma triglycerides, and nonesterified fatty acids indicated an altered carbohydrate and lipid metabolism for the high-temperature group. Although the hatching process of embryos exposed to lower incubation temperatures was also significantly retarded, their embryonic development and growth were strikingly similar to those of the control group.