Effect of cortisol infusion patterns and castration on metabolic and immunological indices of stress response in cattle

Effect of dietary restriction and compensatory growth on performance, carcass characteristics, and metabolic hormone concentrations in Angus and Belgian Blue steers

Compensatory growth (CG) is the ability of an animal to undergo accelerated growth after a period of restricted feeding. However, there is a dearth of information in relation to the effect of genotype on CG response, thus the objective of this study was to evaluate CG response in two contrasting breed types, namely Aberdeen Angus (AN) and Belgian Blue (BB). Crossbred AN × Holstein-Friesian or BB × Holstein-Friesian steers were assigned to one of two treatment groups in a two (genotypes) × two (diets) factorial design. For 99 days, one group (11 AN and 12 BB) was offered a high energy control diet (H-H) whereas the second group (11 AN and 12 BB) was offered an energy restricted diet (L-H). At the end of the differential feeding period (99 days), both groups of animals were then offered a high energy control diet for a further 200 days. All animals were then slaughtered on day-299 of the study. During feed restriction, L-H had lower DM intake (DMI), had greater feed conversion ratio (FCR) and lower plasma concentrations of insulin, IGF-1, leptin, glucose, urea, betahydroxybutyrate and smaller M. longissimus thoracis or lumborum muscle and fat depths compared to H-H steers. During realimentation, there was no difference in DMI between diets; however, L-H had greater live weight gain compared to H-H steers. Overall, H-H consumed greater quantities on a DM basis, however, had a higher FCR compared to L-H steers. By the end of the realimentation period, there was no difference in plasma metabolite or hormone concentrations, linear body measurements, ultrasonically scanned fat depths, carcass conformation, dressing percentage or fat class between H-H and L-H steers. At slaughter, carcass weights were affected by diet with greater values for H-H compared to L-H steers. Genotype affected measures associated with body composition including pelvic width and both muscle and fat depths (P < 0.05). Overall, L-H had a CG (or recovery) index of 0.52 and did not make up for the loss of gains during the differential feeding period; however, M. longissimus thoracis et lumborum, a tissue of high economic value, recovered completely making it a target of interest for further investigation.

Effect of surgical castration with or without oral meloxicam on the acute inflammatory response in yearling beef bulls

Pain management and welfare are increasingly prevalent concerns within animal agriculture. Analgesics may alleviate pain and inflammation associated with castration of beef cattle. This study was conducted to elucidate the effects of surgical castration on the acute inflammatory response and immunomodulation and whether concurrent oral administration of meloxicam (1 mg/kg BW) would alter these responses. On d -1, crossbred bull calves ( = 30; initial BW = 227.4 ± 10.3 kg) were fitted with indwelling jugular catheters and rectal temperature (RT) recording devices, placed into individual stanchions, and randomly assigned to 1 of 3 treatments. Treatment application occurred at h 0 and consisted of 1) intact bull calves treated with sham castration (CON), 2) bulls surgically castrated without meloxicam administration (CAS), and 3) bulls surgically castrated with oral meloxicam (1 mg/kg BW) administration (MEL). Blood samples were collected at 0.5-h intervals from h -2 to 4, 1.0-h intervals from h 4 to 8, and 12-h intervals from h 12 to 72. Serum was analyzed for cortisol and haptoglobin (Hp) concentrations using ELISA. Whole blood was analyzed for complete blood counts at -2, 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h, and RT was recorded in 5-min intervals. Postcastration RT was greatest for MEL (39.04), intermediate for CAS (38.99), and least for CON (38.93°C; ≤ 0.01). Serum cortisol was increased ( < 0.001) for CAS (12.3) and MEL (11.3) compared with CON (6.7 ng/mL) during the postcastration period. At 0.5 and 1.5 h, cortisol concentration was greater in CAS and MEL than CON, whereas at 2 and 2.5 h, cortisol concentration was greatest for CAS, intermediate for MEL, and least for CON (treatment × time, < 0.001). Total white blood cell ( ≤ 0.04), lymphocyte ( ≤ 0.02), and monocyte ( ≤ 0.002) counts were greatest for CAS, intermediate for MEL, and least for CON. Administration of MEL reduced ( ≤ 0.002) eosinophil counts during the postcastration period when compared with CON and CAS. The change in serum Hp, relative to baseline values, was reduced for MEL at 36 ( < 0.01) and 60 h ( ≤ 0.03), and the overall Hp concentration was least for MEL ( < 0.001). Oral administration of meloxicam at the time of castration reduced the acute inflammatory response in castrates, as evidenced by a reduction in Hp and certain leukocyte concentrations; it also caused a delayed increase in RT. Further research is needed to determine if this reduced acute inflammatory response would equate to improved health and/or performance after castration.

The effect of parturition induction treatment on interval to calving, calving ease, postpartum uterine health, and resumption of ovarian cyclicity in beef heifers

The aim of this study was to compare the effects of two parturition induction protocols with a nontreated control group, on interval to calving, calving ease, postpartum uterine health, and ovarian cyclicity in beef heifers. At Day 285 of gestation, 81 crossbred recipient beef heifers carrying purebred Simmental fetuses, were blocked by live-weight, body condition score, expected calving date and fetal sex, and assigned to one of three groups: (1) control (CON; no induction treatment, n = 29); (2) induction with corticosteroids (CORT; n = 27); or (3) induction with corticosteroids plus prostaglandin (CORT + PG; n = 25). Interval from induction to calving in hours and calving ease on a scale of 1 to 5 were recorded. Vaginal mucus samples were collected on Day 21 and Day 42 after calving (Day 0) by means of a Metricheck and scored on a scale of 0 to 3. Reproductive tract examinations were conducted on Day 21 and Day 42 after calving, and uterine cytology samples were obtained on Day 21. A positive cytologic sample was defined as greater than 18% neutrophils in the sample obtained via a cytobrush technique. Cows were considered to have resumed ovarian cyclicity if the presence of the CL was confirmed. Data were analyzed using the Mixed (normally distributed data) and Genmod (nonparametric data) procedures of SAS (v. 9.3). The interval from treatment to calving was longer (P < 0.0001) for CON (161.9 ± 15.12 hours) animals compared with CORT (39.7 ± 11.64 hours) or CORT + PG (32.6 ± 12.10 hours), which did not differ. Treatment did not affect calving difficulty score. There was also no difference in incidence of retained placenta between the three groups. At Day 21 postpartum, cytology score tended to be higher for both induced groups (48%) compared with the control animals (24%), but this was not the case for vaginal mucus score (CON 52%, CORT 70%, and CORT + PG 52%). A higher proportion of CON had an involuted uterus by Day 21 postpartum (69%) compared with both induced groups (CORT 48%, CORT + PG 32%). Day 21 ovarian cyclicity was higher in both CON (52%) and CORT (59%) compared with CORT + PG (29%). By Day 42, there was no difference in ovarian cyclicity or uterine involution between CON and CORT; however, a positive relationship was observed between uterine involution score on Day 21 and return to cyclicity on Day 42 in these two groups. There was a negative relationship between uterine involution score and return to cyclicity in the CORT + PG group, and these animals were slower (P < 0.05) to resume cyclicity by Day 42 with a larger proportion animals having evidence of having resumed postpartum ovarian cyclicity in both CON (P = 0.03) and CORT compared with CORT + PG on Day 42. In conclusion, the use of corticosteroid-based treatments is an effective strategy to advance parturition in full term dams and does not have a negative effect on calving progress or dam health. However, when prostaglandin is also included in the protocol, these treatments may lead to greater delay in uterine involution with increased chance of uterine infection and slower resumption of ovarian cyclicity.

Insulin secretion and signaling in response to dietary restriction and subsequent re-alimentation in cattle

The objectives of this study were to examine systemic insulin response to a glucose tolerance test (GTT) and transcript abundance of genes of the insulin signaling pathway in skeletal muscle, during both dietary restriction and re-alimentation-induced compensatory growth. Holstein Friesian bulls were blocked to one of two groups: 1) restricted feed allowance for 125 days (period 1) (RES, n = 15) followed by ad libitum feeding for 55 days (period 2) or 2) ad libitum access to feed throughout (periods 1 and 2) (ADLIB, n = 15). On days 90 and 36 of periods 1 and 2, respectively, a GTT was performed. M. longissimus dorsi biopsies were harvested from all bulls on days 120 and 15 of periods 1 and 2, respectively, and RNA-Seq analysis was performed. RES displayed a lower growth rate during period 1 (RES: 0.6 kg/day, ADLIB: 1.9 kg/day; P < 0.001), subsequently gaining more during re-alimentation (RES: 2.5 kg/day, ADLIB: 1.4 kg/day; P < 0.001). Systemic insulin response to glucose administration was lower in RES in period 1 (P < 0.001) with no difference observed during period 2. The insulin signaling pathway in M. longissimus dorsi was enriched (P < 0.05) in response to dietary restriction but not during re-alimentation (P > 0.05). Genes differentially expressed in the insulin signaling pathway suggested a greater sensitivity to insulin in skeletal muscle, with pleiotropic effects of insulin signaling interrupted during dietary restriction. Collectively, these results indicate increased sensitivity to glucose clearance and skeletal muscle insulin signaling during dietary restriction; however, no overall role for insulin was apparent in expressing compensatory growth.

Effects of phenotypic residual feed intake on response to a glucose tolerance test and gene expression in the insulin signaling pathway in longissimus dorsi in beef cattle

The objectives of this study were to determine the insulinogenic response to an intravenous glucose tolerance test (GTT) and examine gene expression profiles in the insulin signaling pathway (ISP) in beef animals of differing phenotypic residual feed intake (RFI). Two experiments were conducted. In Exp. 1, a total of 39 Simmental heifers, over 2 yr (yr 1, n = 22, and yr 2, n = 17; mean initial BW = 472 kg [SD = 52.4 kg]), were offered grass silage ad libitum for 104 d. Heifers were subjected to a GTT on d 8 and 65 of the RFI measurement period in yr 1 and 2, respectively. Concentrations of plasma glucose and insulin were measured at -45, -30, -15, 0, 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, and 180 min relative to glucose infusion (0 min). In Exp. 2, a total of 67 Simmental bulls, over 3 yr (yr 1, n = 20; yr 2, n = 33; and yr 3, n = 14; mean initial BW = 431 kg [SD = 63.7 kg]), were offered concentrates ad libitum for 105 d. Biopsies of LM were harvested during the RFI measurement period (yr 1, d 49 and 91; yr 2, d 52 and 92; and yr 3, d 50 and 92). The residuals of the regression of DMI on ADG, midtest metabolic BW (BW(0.75)), and the fixed effect of year, using all animals, were used to compute individual RFI coefficients. Animals were ranked on RFI and assigned to high (inefficient), medium, or low groupings by dividing them into terciles, resulting in 13 heifers and 22, 23, and 22 bulls in their respective RFI groups. In Exp. 1, data from 13 heifers from each of the high- and low-RFI groups, and in Exp. 2, data from the 15 highest and 15 lowest ranking bulls on RFI are reported. In Exp. 1, glucose and insulin response and area under the response curve for glucose and insulin were similar (P > 0.05) between high- and low-RFI heifers. In Exp. 2, no differences (P > 0.05) were found for mRNA expression of 22 genes of the ISP in muscle tissue; however, expression of the transcription factor SREBP1c tended to be positively correlated (r = 0.25, P = 0.07) with RFI. Expression of GLUT4, INPPL1, and SHC increased (P < 0.05) over time, while there was no effect of sample time for any other genes measured. Collectively, these results suggest that insulin response, sensitivity, and associated expression of genes in the ISP within muscle tissue are not contributory factors to variation in RFI. However, further examination of target genes of SREBP1c, which is involved in lipogenesis, may explain some of the biochemical processes underlying variation in phenotypic RFI.

Comparison of VIDAS and radioimmunoassay methods for measurement of cortisol concentration in bovine serum

Radioimmunoassay (RIA) is the “gold standard” method for evaluation of serum cortisol concentration. The VIDAS cortisol test is an enzyme-linked fluorescent assay designed for the MiniVidas system. The aim of this study was to compare the VIDAS method with RIA for measurement of bovine serum cortisol concentration. Cortisol concentrations were evaluated in 40 cows using both VIDAS and RIA methods, the latter as the reference method. A paired Student's t-test, Pearson's correlation analysis, Bland-Altman plot, and Deming regression analysis were used to compare the two methods. There was no statistically significant difference between mean serum cortisol concentrations measured by VIDAS or RIA methods (P = 0.6570). Both methods were able to detect significant differences in mean low and high cortisol concentrations (P < 0.00014 RIA and P < 0.0016 VIDAS). The correlation coefficient was low, but a Bland-Altman plot and Deming regression analysis show neither constant nor proportional error. The VIDAS method produced slightly higher values than RIA, but the difference was small and in no case did the mean value move the normal range. Results suggest that VIDAS method is suitable for the determination of bovine serum cortisol concentration in studies of large numbers of animals.

Minimising pain in farm animals: the 3S approach - 'Suppress, Substitute, Soothe'

Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a '3S' approach accounting for 'Suppress, Substitute and Soothe' by analogy with the '3Rs' approach of 'Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.

Effect of sire breed and genetic merit for carcass weight on the transcriptional regulation of the somatotropic axis in longissimus dorsi of crossbred steers

The somatotropic axis plays an important role in postnatal growth, development, and differentiation of skeletal muscle. The aim of this study was to examine the effect of sire breed and sire EPD for carcass weight (EPD(cwt)) on the expression of components of the somatotropic axis in LM of beef cattle at slaughter. Crossbred Aberdeen Angus (AA; n = 17) and Belgian Blue (BB; n = 16) steers born to Holstein-Friesian dams and sired by bulls with either high (H) or low (L) EPD(cwt) were used in the study. Thus, there were 4 genetic groups [i.e., BBH (n = 8), BBL (n = 8), AAH (n = 8), and AAL (n = 9)]. Blood samples were collected via jugular venipuncture at regular intervals for analysis of plasma concentrations of IGF-1 and insulin. Total RNA was isolated from LM collected at slaughter, and the mRNA expression of IGF-1, IGF-2, their receptors (IGF-1R; IGF-2R), 6 IGFBP, acid labile subunit (ALS), and GH receptor (GHR) was measured by real-time reverse-transcription quantitative PCR. There was no effect of either sire breed or EPD(cwt) on concentrations of circulating IGF or insulin (P > 0.05). Gene expression of IGF-1R and IGFBP3 was upregulated in AA (P < 0.001) compared with BB, whereas IGF-1 was upregulated in H compared with L animals (P < 0.01). Correlation analysis indicated moderate positive associations between gene expression of IGFBP3 and IGF-1 (r = 0.54; P < 0.001) and IGF-1R (r = 0.48; P < 0.01). In addition, correlation analysis revealed that mRNA expression of IGFBP3 was moderately negatively associated with LM area per kilogram of carcass weight (r = -0.40; P < 0.05). Greater gene expression of IGF-1 and reduced transcript abundance of IGFBP3 in muscle may have a role in increased muscle growth potential in steers during the finishing period. These data will contribute to a better understanding of the molecular control of muscle growth at a tissue level in cattle.

The effect of transport by road and sea on physiology, immunity and behaviour of beef cattle

The objective of the study was to investigate the physiological, haematological and immunological responses of weanling heifers transported from Ireland to a feedlot in Spain, and of weanling bulls transported from Ireland to a feedlot in Italy. Physiological variables (including interferon-γ production, cortisol, protein, urea, white blood cell numbers and differentials, and acute phase proteins (haptoglobin and fibrinogen) were used to evaluate the welfare status of animals, before, during and after the respective transport journeys. Age-matched control animals were blood sampled for the same measurements at times corresponding to the transported animals that were retained in Ireland. Heifers transported to Spain lost 7.6% of their initial live weight during the sea crossing to France. However, by the time of their arrival in Spain they had regained 3.3% of their initial live weight and had fully recovered to their pre-transport live weight values within 6 days of arriving in Spain. Weanling bulls lost 7.0% of their live weight during the sea crossing from Ireland to France. The live weight loss in control animals ranged from 1% to 2% during the same period. The percentage of time that bulls spent lying was 63.5% for the sea journey and 35.4% for the journey from the French lairage to the Italian feedlot. The average daily gain (kg) of transported animals was greater (P ≤ 0.05) than control animals from day 11 to 38 (Spain) and day 11 to 40 (Italy), respectively. While transient changes in physiological, haematological and immunological variables were found in the transported and control animals relative to baseline levels, the values were within the normal physiological range for the age and weight of animals involved. Physiological measurements made after the road and sea journeys indicated that the 24h rest in the lairage, with hay and water freely available, allowed animals to recover substantially.

mRNA expression of genes regulating oxidative phosphorylation in the muscle of beef cattle divergently ranked on residual feed intake

Our objective was to evaluate the effects of phenotypic ranking on residual feed intake (RFI) on the transcription of genes 1) involved in the respiratory chain complex and 2) coding for transcriptional factors regulating mitochondrial biogenesis, across two contrasting diet types. Beef heifers (n = 86) fed a diet comprising 70:30 concentrate-corn silage [low forage (LF)] over a 82-day period were ranked on RFI. The 10 highest (feed inefficient, high-RFI) and 10 lowest (feed efficient, low-RFI) ranking animals were selected for the current study. Biopsies of the M. longissimus dorsi were harvested following initial selection (LF diet) and again following a 6 wk period while the animals were offered a high-forage (HF) grass silage-only diet. Real-time PCR was used to quantify mRNA transcripts of 17 genes associated with cellular energetic efficiency. The mRNA expression of UCP3 tended to be upregulated (2.2-fold, P = 0.06) for the high-RFI compared with the low-RFI animals. mRNA transcripts coding for the transcription factor PGC-1α was 1.7-fold higher (P = 0.01) in low compared with high-RFI animals. A phenotype × diet interaction was evident for the abundance of ANT1 mRNA transcript, with greater (P = 0.04) expression levels detected in the low-RFI phenotype during the HF period, but no difference (P = 0.50) between phenotypes during the LF period. A phenotype × diet interaction was also evident for COX II with greater expression levels detected (P = 0.04) in the low compared with the high RFI phenotype while on LF but not the HF diet (P = 0.22). These data suggest an association between cellular energetic efficiency and RFI in cattle.

Repeatability of feed efficiency, carcass ultrasound, feeding behavior, and blood metabolic variables in finishing heifers divergently selected for residual feed intake

This study examined the relationship between feed efficiency and performance, and feeding behavior, blood metabolic variables, and various ultrasonic measurements in finishing beef heifers. Within-animal repeatability estimates of feed intake and behavior, performance, feed efficiency, ultrasonic body measures, and plasma analytes across the growing and finishing stages of the lifespan of the animal were also calculated. Fifty heifers previously ranked as yearlings on phenotypic residual feed intake (RFI) were used. Animals [initial BW = 418 (SD = 31.5) kg] were offered a TMR diet consisting of 70:30 concentrate and corn silage on a DM basis (ME 10.7 MJ/kg of DM; DM 530 g/kg) for 84 d. Feeding duration (min/d) and feeding frequency (events/d) were calculated for each animal on a daily basis using a computerized feeding system. Ultrasonic kidney fat and lumbar and rump fat and muscle depths were recorded on 3 equally spaced occasions during the experimental period. Blood samples were collected by jugular venipuncture on 4 occasions during the experimental period and analyzed for plasma concentrations of IGF-I, insulin, and various metabolites. Phenotypic RFI was calculated for all animals as the residuals from a regression model regressing DMI on ADG and midtest BW(0.75). Repeatability was calculated for several traits both within and between production phase using intraclass correlation and Pearson correlation coefficients as appropriate. Overall ADG, DMI, G:F, and RFI were 1.17 kg/d (SD = 0.19), 10.81 kg/d (SD = 1.02), 0.11 kg of BW gain/kg of DM (SD = 0.02), and 0.00 kg of DM/d (SD 0.59). Daily feeding events and eating rate tended to be positively correlated (P = 0.08) with RFI. Ultrasonic kidney fat depth tended to be related to G:F (r = -0.28; P = 0.07), and kidney fat accretion tended to be related to RFI (r = 0.29; P = 0.08). Plasma urea (r = 0.38; P < 0.01), β-hydroxybutyrate (r = 0.40; P < 0.01), and insulin (r = 0.23; P = 0.07) concentrations were correlated with RFI. Plasma glucose (r = -0.25; P = 0.07), glucose:insulin (r = 0.33; P < 0.05), and insulin (r = -0.30; P < 0.05) were associated with G:F. However, systemic IGF-I was unrelated (P > 0.10) to any measure of feed efficiency. Repeatability estimates within the finishing period for DMI, feeding duration, feeding events, feed intake/feeding event, and eating rate were 0.34, 0.37, 0.60, 0.62, and 0.56, respectively. Repeatability estimates (P < 0.001) between the growing and finishing phases for DMI, G:F, and RFI were r = 0.61, r = 0.37, and r = 0.62, respectively. Moderate to strong repeatability values (ranging from r = 0.40 to 0.76; P < 0.001) were obtained for feeding behavior traits between the yearling and finishing phases. We conclude that RFI and feeding behavior are repeatable traits and that some plasma analytes may be potential indicators of RFI in beef cattle.

Banding or Burdizzo castration and carprofen administration on peripheral leukocyte inflammatory cytokine transcripts

The objective was to investigate if Banding or Burdizzo castration of bulls would alter the gene expression profile of a range of peripheral leukocyte inflammatory cytokines (IL-1, IL-6, IL-8, IL-10, interferon-γ and tumor necrosis factor-α) and to determine if the administration of carprofen (C) before castration would affect the expression of these genes. Thirty Holstein-Friesian bulls (5.5 months; Mean 191±(SEM) 3.7 kg) were blocked by weight and randomly assigned to one of five treatments: (1) untreated control (CON); (2) Banding castration at 0 min (BAND); (3) BAND following an i.v. injection of 1.4 mg/kg BW of carprofen (C) at -20 min (BAND+C); (4) Burdizzo castration at 0 min (BURD); or (5) BURD following 1.4 mg/kg BW of carprofen at -20 min (BURD+C). Blood samples were collected at 1 h before castration and 6, 24 and 48 h post-castration for routine hematology and quantitative real-time PCR analysis of cytokine gene expression analysis. Generally, there were no differences (P>0.05) among treatment groups in hematological variables following castration. Cortisol concentrations were unchanged throughout the experimental period in CON bulls. BURD animals had greater cortisol concentrations than BAND and CON animals at 6 h post treatment. Transitory effects were observed only in the expression of IL-6 and TNF-α. The relative expression of IL-6 was greater in the BURD than in the BAND treatment (P<0.05) at 24 h post-castration and was greater in the BURD+C group than in the BURD group (P<0.05) at 48 h. The relative expression of TNF-α was greater in BAND than in the BURD group (P<0.05) at 48 h. In conclusion, these findings indicate that Banding or Burdizzo castration did not have any major effect on peripheral leukocyte inflammatory cytokine gene expression; Banding castration caused a greater pro-inflammatory cytokine gene expression reaction than Burdizzo castration and carprofen administration can affect IL-6 gene expression levels in BURD castrated animals.

Altered "set-point" of the hypothalamus determines effects of cortisol on food intake, adiposity, and metabolic substrates in sheep

Chronic elevation of glucocorticoid concentrations is detrimental to health. We investigated effects of chronic increase in plasma cortisol concentrations on energy balance and endocrine function in sheep. Because food intake and reproduction are regulated by photoperiod, we performed experiments in January (JAN) and August (AUG), when appetite drive is either high or low, respectively. Ovariectomized ewes were treated (intramuscularly) daily with 0.5mg Synacthen Depot(R) (synthetic adrenocorticotropin: ACTH) or saline for 4 wk. Blood samples were taken to measure plasma concentrations of cortisol, luteinising hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), leptin, insulin, and glucose. Adrenocorticotropin treatment increased concentrations of cortisol. During JAN, treatment reduced food intake transiently, but increased food intake in AUG. Leptin concentrations were reduced and glucose concentrations were greater in AUG, and insulin concentrations were similar throughout the year. Treatment with ACTH increased leptin concentrations in AUG only, whereas insulin concentrations increased in JAN only. Synacthen treatment increased glucose concentrations, with a greater effect in JAN. Changes in truncal adiposity and ACTH-induced cortisol secretion were positively correlated in JAN and negatively correlated in AUG. Treatment reduced the plasma LH pulse frequency in JAN and AUG, with an effect on pulse amplitude in JAN only. Treatment did not affect plasma GH or FSH concentrations. We conclude that chronically elevated cortisol concentrations can affect food intake, adiposity, and reproductive function. In sheep, effects of chronically elevated cortisol concentrations on energy balance and metabolism depend upon metabolic setpoint, determined by circannual rhythms.

Characterisation of endometrial gene expression and metabolic parameters in beef heifers yielding viable or non-viable embryos on Day 7 after insemination

The aim of the present study was to compare the hormonal and metabolic characteristics and endometrial gene expression profiles in beef heifers yielding either a viable or degenerate embryo on Day 7 after insemination as a means to explain differences in embryo survival. Oestrus was synchronised in cross-bred beef heifers (n = 145) using a controlled internal drug release (CIDR)–prostaglandin protocol. Heifers (n = 102) detected in standing oestrus (within 24–48 h after CIDR removal) were inseminated 12–18 h after detection of oestrus (Day 0) with frozen–thawed semen from a single ejaculate of a bull with proven fertility. Blood samples were collected from Day 4 to Day 7 after oestrus to measure progesterone (on Days 4, 5 and 7), insulin and insulin-like growth factor (IGF)-I (on Days 4 and 6) and urea (on Day 7) concentrations. All animals were killed on Day 7. Uterine pH was determined at the time of death. Animals from which an embryo was recovered were classified as either having a viable embryo (morula/blastocyst stage; n = 32) or a retarded embryo (arrested at the two- to 16-cell stage; n = 19). In addition, 14 single-celled unfertilised oocytes were recovered, giving an overall recovery rate of 64%. There was no significant difference in the blood parameters determined or uterine pH at the time of death between heifers with either a viable or retarded embryo. The relative abundance of nine transcripts (i.e. MOGAT1, PFKB2, LYZ2, SVS8, UHRF1, PTGES, AGPAT4, DGKA and HGPD) of 53 tested in the endometrial tissue differed between heifers with a viable or retarded embryo. Both LYZ2 and UHRF1 are associated with regulation of the immune system; PFKFB2 is a mediator in glycolysis; MOGAT, AGPAT4 and DGKA belong to the triglyceride synthesis pathway; and PTGES and HGPD belong to the prostaglandin pathway. Both these metabolic pathways are important for early embryonic development. In conclusion, retarded embryo development in the present study was not related to serum progesterone, IGF-I, insulin or urea concentrations, nor to uterine pH at the time of death. However, altered expression of genes involved in the prostaglandin and triglyceride pathways, as well as two genes that are closely associated with the regulation of immunity, in the endometrium may indicate a uterine component in the retardation of embryo development in these beef heifers.

Effect of divergence in residual feed intake on feeding behavior, blood metabolic variables, and body composition traits in growing beef heifers

This study examined the relationship of feed efficiency and performance with feeding behavior, blood metabolic variables, and various body composition measurements in growing beef heifers. Individual DMI and growth were measured in yearling Limousin x Holstein-Friesian heifers [n = 86; initial BW = 191.8 (SD = 37) kg] fed a TMR diet comprising 70:30 concentrate:corn silage on a DM basis (ME of 2.65 Mcal/kg of DM; DM of 580 g/kg) for 82 d. Meal duration (min/d) and meal frequency (events/d) were calculated for each animal on a daily basis using an Insentec computerized feeding system. Physical measurements as well as ultrasonic fat and muscle depths were recorded on 3 equally spaced occasions during the experimental period. Blood samples were collected by jugular venipuncture on 4 equally spaced occasions and analyzed for plasma concentrations of IGF-I, insulin, leptin, and various metabolites. Phenotypic residual feed intake (RFI) was calculated for all animals as the residuals from a multiple regression model regressing DMI on ADG and midtest BW(0.75). Overall, ADG, DMI, feed conversion ratio (FCR), and RFI were 1.51 (SD = 0.13), 6.74 (SD = 0.99), 4.48 (SD = 0.65), and 0.00 (SD = 0.48) kg/d, respectively. Residual feed intake was positively correlated with DMI (r = 0.47) and FCR (r = 0.46), but not with ADG or midtest BW. Positive correlations (ranging from r = 0.27 to r = 0.63) were estimated between ultrasonic measures of final lumbar fat and lumbar fat accretion over the test period and DMI, FCR, and RFI. The inclusion of gain in lumbar fat to the base RFI model increased R(2) (0.77 vs. 0.80) value for the degree of variation in DMI not explained by midtest BW and ADG alone. The Pearson rank correlation between RFI and carcass-adjusted RFI (RFI(c)) was high (r = 0.93). From the plasma analytes measured, NEFA (r = -0.21; P < 0.05) and beta-hydroxybutyrate (r = 0.37; P < 0.05) concentrations were correlated with RFI. Plasma leptin (r = 0.48), glucose:insulin (r = -0.23), NEFA (r = -0.32), and beta-hydroxybutyrate (r = 0.25) were associated with FCR. However, systemic IGF-I and insulin were unrelated (P > 0.05) to any measure of feed efficiency. The feeding behavior traits of eating rate, daily feeding events, and nonfeeding events were positively correlated (P < 0.05) with RFI and RFI(c). This multifactorial study provides new information on some of the biological processes responsible for variation in feed efficiency in beef cattle.

Temporal patterns of inflammatory gene expression in local tissues after banding or burdizzo castration in cattle

Background

Castration of male cattle has been shown to elicit inflammatory reactions and acute inflammation is initiated and sustained by the participation of cytokines.

Methods

Sixty continental × beef bulls (Mean age 12 ± (s.e.) 0.2 months; Mean weight 341 ± (s.e.) 3.0 kg) were blocked by weight and randomly assigned to one of three treatments (n = 20 animals per treatment): 1) untreated control (Con); 2) banding castration at 0 min (Band); 3) Burdizzo castration at 0 min (Burd). Samples of the testis, epididymis and scrotal skin were collected surgically from 5 animals from each group at 12 h, 24 h, 7 d, and 14 d post-treatment, and analysed using real-time PCR. A repeated measurement analysis (Proc GLM) was performed using SAS. If there was no treatment and time interaction, main effects of treatment by time were tested by ANOVA.

Results

Electrophoresis data showed that by 7 d post-castration RNA isolated from all the testicle samples of the Burd castrated animals, the epididymis and middle scrotum samples from Band castrates were degraded. Transitory effects were observed in the gene expression of IFN-γ, IL-6, IL-8 and TNF-α at 12 h and 24 h post treatment. Burd castrates had greater (P < 0.05) testicular IFN-γ mRNA levels compared with Band and Con animals, but lower (P < 0.05) testicular TNF-α mRNA levels compared with Con animals. Band castrates had greater (P < 0.05) testicular IL-6 mRNA levels than Burd castrates at 12 h post-castration. Burd castrates had greater (P < 0.05) testicular IL-8 mRNA levels than Band and Con animals at 24 h post-castration. In the epididymis, Burd castrates had greater (P < 0.05) IL-6 mRNA (both at 12 h and 24 h post treatment) and IL-8 mRNA (12 h post treatment) levels compared with Band and Con animals; Burd castrates had greater (P = 0.049) IL-10 mRNA levels than Band castrates at 12 h post-castration.

Conclusion

Banding castration caused more inflammatory associated gene expression changes to the epididymis and scrotum than burdizzo. Burdizzo caused more severe acute inflammatory responses, in terms of pro-inflammatory cytokine gene expression, in the testis and epididymis than banding.

Corticosteroid effects on blood gene expression in Duchenne muscular dystrophy

Though Deflazacort and prednisone improve clinical endpoints in Duchenne muscular dystrophy (DMD) patients, Deflazacort produces fewer side effects. As mechanisms of improvement and side effect differences remain unknown, we evaluated effects of corticosteroid administration on gene expression in blood of DMD patients. Whole blood was obtained from 14 children and adolescents with DMD treated with corticosteroids (DMD-STEROID) and 20 DMD children and adolescents naïve to corticosteroids (DMD). The DMD-STEROID group was further subdivided into Deflazacort and prednisone groups. Affymetrix U133 Plus 2.0 expression microarrays were used to evaluate mRNA expression. Expression of 524 probes changed with corticosteroids, including genes in iron trafficking and the chondroitin sulfate biosynthesis pathway. Deflazacort compared with prednisone yielded 508 regulated probes, including many involved in adipose metabolism. These genes and pathways help explain mechanisms of efficacy and side effects of corticosteroids, and could provide new treatment targets for DMD and other neuromuscular disorders.

Effect of 12-hour road transportation on physiological, immunological and haematological parameters in bulls housed at different space allowances

The effects of transporting Holstein Friesian bulls (n=72; bodyweight 403+/-3.5 kg) for 12h by road were examined. Adrenal, haematological and immune responses, body temperature and performance were recorded. The animals had been previously housed for 96 days at three space allowances (1.2, 2.7 or 4.2m(2) per bull). The bulls were allocated to one of two treatments: T (transport for 12h; n=16 per space allowance) and C (control; n=8 per space allowance). Basal cortisol plasma concentrations and interferon (IFN)-gamma production from cultured lymphocytes did not show any statistically significant difference (P>0.05) following the housing period. Removing bulls from their home pens and walking them to the pre-loading crush facility, loading onto the transporter, and unloading following the 12h road journey, significantly (P<0.001) increased plasma cortisol concentration. The bulls housed at 4.2m(2) had greater (P<0.05) plasma cortisol concentrations than bulls housed at 1.2m(2) at loading, unloading, or on return to the crush holding facility; those housed at 1.2m(2) had greater (P<0.05) plasma cortisol concentrations than bulls housed at 2.7 and 4.2m(2) in their home pens after transport. There was an increased (P<0.05) plasma cortisol response in the T than in the C bulls following adrenocorticotrophic hormone administration. Transport significantly reduced (P<0.05) IFN-gamma production, lymphocyte % and body weight and significantly increased (P<0.05) neutrophils, eosinophils, packed cell volume, red blood cell numbers and haemoglobin. In conclusion, housing bulls for 96 days in a range of space allowances did not affect basal cortisol response or immune function parameters. Whereas transport increased plasma cortisol and reduced the immune response in the short-term, the changes were transient and within normal physiological ranges, suggesting that 12h road transport had no adverse effect on welfare status over the longer term. Furthermore, transport of bulls housed at increased space allowance (4.2m(2)/bull) resulted in a greater plasma cortisol response, albeit still within normal physiological range.

Pituitary, adrenal, immune and performance responses of mature Holstein x Friesian bulls housed on slatted floors at various space allowances

The effect of various space allowances on the pituitary, adrenal and immune responses and on performance was investigated in 72 mature Holstein x Friesian beef bulls. The animals (weighing 403+/-3.5 kg) were blocked by weight and randomly assigned to two groups (familiar, F, and unfamiliar, UF) x three treatments (1.2, 2.7 and 4.2m(2) per bull; n=24 per space allowance), and housed for 83 days in 18 pens (n=4 per pen). Blood samples were collected on days -1, 0, 3, 14, 36 and 77 with respect to mixing and housing on day 0. The bulls were given exogenous adrenocorticotrophic hormone (ACTH) on day 3 and corticotrophin-releasing hormone (CRH) on days 14, 36 and 77. Basal plasma cortisol concentration was not affected (P>0.05) by mixing F and UF bulls. On day 3, basal cortisol was greater (P<0.05) in bulls housed at 1.2 than those at 2.7 and 4.2m(2) space allowances while no effect was observed in ACTH-induced plasma cortisol concentration among treatments. Following CRH administration, there was no effect (P>0.05) of treatment and treatment x time on plasma ACTH concentration. On day 14, interferon-gamma production was lower (P<0.05) in the bulls housed at 4.2 vs. 2.7 m(2) and was intermediate but not significantly different (P>0.05) for those housed at 1.2m(2). Animals housed at either space allowances had significant (P<0.05) neutrophilia, lymphopenia, eosinopenia and decreased haemoglobin on day 3 compared with day 0. The liveweight gain from days 0 to 83 was lower (P<0.05) in bulls housed at 1.2 compared with those at 2.7 and 4.2m(2). Housing bulls at 1.2m(2) space allowance had a detrimental effect on their growth and was associated with an acute rise in plasma cortisol concentration (on day 3) compared with those having space allowances of 2.7 and 4.2m(2)/bull.