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1.
The effects of two levels of nutrition (400 g and 1000 g air dry matter milk substitute powder per day) and three ages of weaning (rive, nine and 13 weeks) on cellular immune responses were determined in 32 calves. The lower level of nutrition was found to increase skin sensitivity responses to keyhole limpet haemocyanin (KLH) and decrease lymphocyte blastogenesis test (LBT) responses to ConA and pokewood mitogen (P<0·05). Weaning at five weeks old resulted in increased KLH skin responses at nine weeks old compared with unweaned calves and decreased LBT responses to ConA and phyto-haemagglutinin at 10 weeks old compared with calves weaned at nine weeks old (P<0·05). Weaning at five weeks old also increased peripheral blood concentrations of BoCD2+ and BoCD8+ lymphocytes (P<0·05). The results show that the choice of husbandry conditions alters cellular immune responses in young calves and suggest that early weaning effects are essentially nutritional.  相似文献   

2.
Biomarker responses to weaning stress in beef calves   总被引：1，自引：0，他引：1  
The study objective was to investigate the physiological effects of weaning on beef calves and identify a panel of blood-based welfare biomarkers. On the day (d) of weaning (d 0), 16 spring-born, single-suckled, beef bull calves that previously grazed with their dams at pasture, were assigned to one of two treatments: (1) control (n = 8), calves were loose-housed with their dam, (2) weaned (n = 8), calves were abruptly separated from their dam and loose-housed. Jugular blood was collected on d −4, 0, 1, 2, 3, 7, and 14 relative to weaning (d 0) and assayed for inflammatory and steroid variables. Total leukocyte counts were measured in whole blood. It is concluded that neutrophil number is a robust biomarker of stress and that plasma CXCL8 is a sensitive indicator of stress in weaned and control calves. In future studies, these two biomarkers should be central to the characterisation of stress responses.  相似文献   

3.
Immune modulation by Ostertagia ostertagi and the effects of diet   总被引：1，自引：0，他引：1  
IgG1 antibody responses to Ostertagia ostertagi third stage larvae (L3) and the third party antigen, keyhole limpet haemocyanin (KLH), and faecal egg counts were determined in calves infected with a single dose of O. ostertagi and in uninfected, pair-fed calves. The infected and uninfected calves were given diets either high (H) or low (L) in protein and energy. The diets were within the normal range of husbandry practice in the UK. IgG1 antibody responses to L3 antigen were significantly greater from 6 weeks post-infection in infected calves given the L diet than in infected calves given the H diet (P less than 0.05). The effects of diet and infection on anti-KLH IgG1 responses were independent of each other. IgG1 responses to KLH were decreased by infection and by the L diet compared with the H diet.  相似文献   

4.
Magnesium supplementation has been shown to benefit feedlot cattle and is typically added at high concentrations to mineral supplements for calves grazing wheat pasture. Two experiments were conducted to determine the effects of Mg-mica supplementation on performance and serum mineral concentrations of stocker calves grazing wheat pasture. Supplemental Mg was provided at 6.1 g/d of supplemental Mg/ animal, Monday through Friday. In Exp. 1, 36 mixed-breed stocker calves (243 ± 3.9 kg BW) were stratified by BW and gender and allocated randomly to one of nine groups of four animals for a 112-d grazing study. Weight gain, shrink percentage, and serum Mg, Ca, K, Cu, and Zn concentrations did not differ (P>0.10) among calves fed either weathered Mg-mica (WMM), unweathered Mg-mica (UMM), or MgO. All serum mineral concentrations were within normal physiological ranges. In Exp. 2, 64 mixed-breed stocker steers (275 ± 1.7 kg BW) were stratified by BW and allocated randomly to one of 16 groups of four animals. Weight gain during a 50-d grazing study and subsequent feedlot period did not differ (P>0.10) among calves fed either no added Mg source or WMM, UMM, or MgO. Serum Cu was higher (P<0.05), and serum Mg was lower (P<0.05), from steers fed MgO, but all serum mineral concentrations were within normal physiological ranges. Although Mg-mica is relatively high in Fe (4%), using it as a supplemental Mg source appeared to have no negative impact on growth performance or serum mineral concentrations of calves grazing wheat pasture.  相似文献   

5.
This experiment was conducted to investigate the effects of sodium humate (HNa) and glutamine (Gln) alone or combined supplementation on growth performance, diarrhea incidence, blood parameters, and intestinal microflora of weaned Holstein calves. In a 14-day experiment, 40 calves at 51 ± 3 days of age were randomly allocated to four treatment groups: (1) NC (basal diet), (2) NC + 5% HNa, (3) NC + 1% Gln, and (4) NC + 5% HNa + 1% Gln. Calves combined supplementation with HNa and Gln had a higher (P < .05) ADG, serum concentration of glucose (GLU), IgA, and IgG but lower fecal scores, diarrhea incidence, serum concentration of TNF-α, and IL-10 compared with NC group (P < .05). Compared with NC group, HNa + Gln group showed higher (P < .05) serum GSH and T-AOC activities but lower (P < .05) concentration of MDA and D-lac. Furthermore, the abundances of Prevotella ruminicola, Bifidobacterium, and Lactobacillus in rectal digesta were increased (P < .05), but the Escherichia coli was significantly decreased. In conclusion, combined supplementation with HNa and Gln can effectively improve the immune status, antioxidant capacity, and intestinal microflora of the weaned calves while reducing diarrhea incidence.  相似文献   

6.
The efficacy of keyhole limpet haemocyanin (KLH) as a test antigen was determined in calves. Humoral and cellular (in vivo and in vitro) responses were compared. Calves were immunized with KLH at either 3 weeks or up to 5 months of age and immune responses were subsequently tested. Class and subclass antibody responses were detected by ELISA, lymphocyte blastogenesis was measured using a whole blood culture technique (LTT) and skin sensitivity responses were measured as an increase in skin thickness following intradermal injection. In young calves, skin test responses were maximal at 24 h and were found to correlate with IgG1 and IgG2 responses (P less than 0.01), with IgA (P less than 0.05) but not with IgM or LTT. Histological examination of skin swellings found a sequence of cellular events, with polymorphonuclear cells dominating until 48 h after intradermal injection, when mononuclear cells became involved. However, in older calves, skin test responses correlated not only with IgG1 and IgA responses but also with lymphocyte transformation (P less than 0.05). These findings suggest that, while immune responses to KLH may be a useful indicator of immune competence in calves, interpretation should be made with caution particularly in young calves.  相似文献   

7.
Female calves (n = 108) were assigned to 6 cold milk feeding treatments in two experiments for a 70-day period. Live-weight (LW) was measured weekly, with an additional LW taken at day 410 and post-calving for animals in experiment 1. In Experiment 1, the effect of feeding frequency and age of turnout to pasture on calf performance and 1st lactation milk yields were evaluated. The whole milk (WM) feeding treatments applied were (i) once daily feeding (OD), (ii) twice daily feeding (TD), (iii) OD feeding, outdoors at 38 days (ODO). In Experiment 2, the effects of feeding milk replacer (MR) as opposed to WM and age of turnout to pasture on calf performance were evaluated. The treatments applied were (i) OD feeding with WM (OD), (ii) OD feeding with milk replacer (MR) (ODMR), (iii) OD feeding with MR, outdoors at 38 days (ODMRO). Experiment 1: There were no differences (P > 0.05) in LW or average daily gain between TD and OD calves at day 80 or 410. ODO calves had lower LW at day 80 as compared to OD or TD (P < 0.001). Calf LW at day 80 was 86, 89 and 85 kg and at day 410 was 304, 309 and 316 kg for OD, TD and ODO, respectively. Milk feeding frequency or time of calf turnout had no effect on LW post calving, milk composition or 1st lactation milk yields. Experiment 2: Total LW at day 80 was higher (P < 0.05) for ODMR compared to OD or ODMRO calves. Calf LW was 87, 95, and 88 kg for OD, ODMR and ODMRO, respectively. However, LW at day 410 did not differ between treatments.This study showed that while some differences were observed in calf LW at day 80, these differences had no effect on LW at day 410 or 1st lactation milk yield. It can be concluded that calves can be successfully reared when fed OD with WM or MR, indoors and when turned out to pasture at 38 days of age.  相似文献   

8.
The effects of (i) frequency of herbage allocation and (ii) herbage allowance on ewe and subsequent lamb performance, when autumn-saved (extended grazed, deferred grazed) pasture is grazed (between 28 Nov and 30 Jan) by spring lambing ewes during mid gestation, were studied in Experiment 1. This involved 72 crossbred ewes from days 41 to 104 of gestation allocated to one of four treatments; two herbage dry matter (DM) allowances (1.0 and 1.8 kg per ewe) by two frequencies of herbage allocation (daily or twice weekly). From day 105 of gestation to parturition all ewes were housed and offered grass silage (ad libitum) plus a total of 19 kg concentrate. Increasing herbage allowance improved ewe body condition score (P < 0.01) and live weight (P < 0.01) at the end of deferred grazing, and tended to increase herbage intake (P = 0.08) during deferred grazing. Reducing the frequency of herbage allocation increased lamb birth weight (P < 0.05). Otherwise frequency of herbage allocation did not alter (P > 0.05) forage intake or utilization, or ewe or subsequent lamb performance. In Experiment 2, the effects of herbage allowance (1.0 or 1.8 kg DM per ewe), frequency of allocation (daily, twice weekly) and grazing date (28 Nov. to 4 Dec., 12 to 18 Dec., 2 to 8 Jan. and 23 to 29 Jan.) during deferred grazing on herbage yield and composition at four subsequent harvest dates (4, 18 and 25 Apr., and 25 May) were evaluated in a split-plot design consisting of 128 plots. Delaying grazing date reduced herbage yield (P < 0.05) and the concentrations of neutral detergent fibre (NDF; P < 0.01) and acid detergent fibre (ADF; P < 0.01). Delaying harvest date increased herbage yield (P < 0.001) and reduced (P < 0.001) the concentrations of NDF, ADF and metabolisable energy. Increasing herbage allowance at grazing increased (P < 0.05) subsequent herbage yield. Frequency of herbage allocation during deferred grazing did not affect (P > 0.05) subsequent herbage yield. There was a significant interaction (P < 0.001) between grazing date and harvest date for herbage yield. It is concluded that to maximise stock carrying capacity and reduce labour requirement a herbage DM allowance of 1 kg per ewe per day, allocated twice weekly, is sufficient for ewes on deferred grazed pasture in mid pregnancy.  相似文献   

9.
The effects of Ostertagia ostertagi infection and diet on antibody responses to O. ostertagi third stage larval (L3) antigen and to an unrelated antigen, Keyhole Limpet Haemocyanin (KLH) were determined in calves experimentally infected with 3000 L3 on alternate days for 6 weeks. Calves were given one of two diets, and were either infected or not infected with O. ostertagi L3. The diets were either high (H) or low (L) in protein/energy and were within the range of normal husbandry practice in the UK. Both IgG1 and IgG2, but not IgA, responses to L3 antigen were increased in the L-diet compared with the H-diet. IgA responses to L3 antigen were not affected by dietary treatment. The effects of diet and infection on anti-KLH IgG1 were independent of each other; IgG1 anti-KLH responses were decreased by infection and by the L-diet compared with the H-diet. The data suggest that there is a strong interrelationship between diet and immunity during nematode infections.  相似文献   

10.
Two experiments were conducted to determine the effects of pre-weaning vitamin E, Se, and Cu supplementation on performance and immune response in stressed calves. In Exp. 1, 71 Hereford x Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (E), 3) control plus 10 mg Cu/kg DM (CU), or 4) a combination of E and CU treatments (ECU). In Exp. 2, 80 Hereford (Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 0.3 mg Se/kg DM (SE), 3) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (LOWE), 4) control plus 1000 IU vitamin E + 0.3 mg Se/kg DM (MEDE), or 5) control plus 1500 IU vitamin E + 0.3 mg Se/kg DM (HIE). Treatments continued for 49 (Exp. 1) or 53 d (Exp. 2) prior to weaning. At weaning all calves were transported to feedlot facilities. In Exp. 1, vitamin E tended (P<0.09) to improve post-weaning ADG and reduce (P<0.06) plasma haptoglobin (Hp), but had no effect on plasma α-tocopherol. Dietary Cu tended to increase (P<0.01) liver Cu stores, and antibody titers to bovine viral diarrhea (BVD) were greater (P<0.04) at weaning in CU and E calves. In Exp. 2, vitamin E tended to increase serum α-tocopherol (P<0.06) and cortisol (P<0.08). Vitamin E and Se supplementation may improve post-weaning performance and decrease plasma Hp concentrations in stressed calves.  相似文献   

11.
Dynamics and quantitative analyses of monospecific antibody during the primary and secondary humoral responses were determined in outbred rabbits and in the F1 generation of breeding with siblings. The antibody response in rabbits immunized with Keyhole Limpet Hemocyanin (KLH) was studied during a 4-month immunization period. ELISA determination of anti-KLH Ig and anti-KLH IgG alone, in preimmune and immune rabbit sera, was performed. Antibody response in both groups of rabbits was similar when assessed by anti-rabbit Ig but displayed differences when assessed by anti-rabbit IgG. A statistically significant increase in anti-KLH IgG was observed in the F1 inbred rabbits compared to the control group after primary immunization from days 14 to 35. Immunomodulation also elicited differences in the antibody response in the two groups of animals. C3-binding glycoprotein isolated from Cuscuta europea (C3bgp), applied simultaneously with antigen (KLH), produced a much stronger secondary immune response than the antigen alone, in both experimental groups. The enhancement of anti-KLH Ig in C3bgp-treated inbred rabbits was statistically significant in comparison with nontreated inbred rabbits. A significant increase in anti-KLH IgG was observed only for the inbred group after treatment with C3bgp. The results demonstrate that the F1 generation of breeding with sibling leads to significant differences in antibody responses to immunization compared with outbred rabbits, as well as to immunomodulation with C3bgp.  相似文献   

12.
Angus (A), Hereford (H), Jersey (J), Simmental (S) and Brahman (B) bulls (202), were mated to A and H cows (855 cow-years) to produce F1 calves. Cows were randomly assigned within age and breed to two pasture programs. The two pasture programs were expected to differ in particular with respect to the energy level offered to the cows during winter (tall fescue hay versus corn silage). Effects of genotypes, pasture program and of their interactions on preweaning traits were studied. Differences (P< 0.05) between pasture programs were found only for frame and muscle scores. Marginal means for A dams were higher (P<0.05) than those for H cows for all traits, except birth weight. Calves sired by B bulls were heavier (P<0.01) at birth than those sired by S, A and H, and J bulls. For the other traits, S-sired calves tended to have the largest estimated means, followed by calves of B bulls, then by the average of calves sired by A and H bulls and finally by J-sired offspring. Significant (P< 0.05) breed of sire × breed of dam interactions involved only extreme sire breeds. All hypotheses involving pasture program × breed of sire interactions were not significant. Muscle score was the only trait affected (P< 0.05) by a pasture × breed of dam interaction. However, its effect was only magnitudinal. Birth weight was the only trait not affected at all by the pasture program × breed of sire × breed of dam interaction. In the other traits, significant interactions reflected changes in the magnitude of the response rather than in the ranking of genotypes across pasture programs.  相似文献   

13.
The aim of the study was to evaluate the physiometabolic responses to stress in hybrid suckling piglets that were weaned and transported at different ages on a paved road under two vehicle conditions: with and without a layer of straw bedding. The piglets were weaned and transported at the following ages: 8, 15 and 22 days. The duration of each trip was 1 h. The piglets in each group were further divided into two sub‐groups for two distinct experimental transport conditions: (1) over the road with straw bedding; and (2) over the same road but without straw bedding. A total of three repetitions were performed for each experimental condition. In order to assess their responses to weaning‐ and transport‐induced stress, the study evaluated a thorough physiometabolic blood profile. The 8‐ and 15‐day‐old piglets transported without straw bedding showed increases in their pCO2, blood glucose, blood lactate levels and the percentage of hematocrit, but a decrease of pO2 upon arrival (P < 0.05). In contrast, the 22‐day‐old piglets transported on the same road with straw bedding were able to re‐establish their blood concentrations of lactate, pCO2, pO2, Na+, K+, Ca2+ and pH during the trip (P < 0.05).  相似文献   

14.
Near infrared spectroscopy (NIBS) was used to detect changes in brain oxygenation in five tranquilised calves that were placed on a hypoxic gas mixture (10 per cent O2/90 per cent N2) and hyperoxic gas mixture (30 per cent O2/70 per cent N2) for five minutes at each concentration. A NIRO 500 (Hamamatsu, Japan) was used for the NIBS, with the incident light source and separate detector (optodes) placed on shaved skin on the most dorsal surface of the frontal bone. Sequential arterial blood gas sample analyses provided confirmation of the appropriate change in systemic oxygenation status. By the end of the five-minute-period of breathing 10 per cent oxygen, NIBS of the calf head detected highly significant changes in haemoglobin oxygenation reflective of hypoxaemia, with oxyhaemoglobin decreasing by 23·5 units (P<0·01) and deoxyhaemoglobin increasing by 45·6 units, (P<0·01) from the baseline of breathing room air. Total haemoglobin (oxyhaemoglobin + deoxyhaemoglobin) showed a significant increase of 22·1 units (P<0·05) but there was no significant change in LAIRS determined cytochrome aa3 oxygenation. Concomitant blood gas alterations included significant decreases in Pa)2 (−27·8 mmHg, P<0·01), haemoglobin saturation (−29·0 per cent, P<0·05), and PaCO2 (−7·8 mmHg, P<0·05) and significantly increased blood pH (0·059, P<0·05). At the end of the five minutes of breathing 30 per cent oxygen NIBS of the calf head detected significantly increased oxyhaemoglobin (13·1 units, P<0·01) and decreased deoxyhaemoglobin (−13·7 units, P<0·05) when compared with baseline breathing of room aim. Total haemoglobin and cytochrome aa3 were unchanged from baseline. The accompanying arterial blood gas changes included significant increases in PaO2 (30·9 mmHg, P<0·05), arterial O2 saturation (11·7 per cent, P<0·05), and significantly decreased pH (−0·026, P<0·05), This study showed that NIRS can be used to continuously and non-invasively detect cerebral oxygenation changes in the live calf in response to both increased and decreased systemic arterial oxygen. Additionally, despite induction of profound hypoxaemia, cytochrome aa3 in the brain did not appear to become reduced.  相似文献   

15.
Angus Plus cattle offer advantages for heat tolerance and forage utilization by introduction of Brangus and Brahman to Angus. To evaluate its adaptability in Hawaii Islands, we reported the growth performances of 213 F1 Angus Plus calve grazing on pasture. Least-square means of pre-weaning ADG ranged from 1,087 to 1,167 g in bull calves and from 1,030 to 1,048 g in heifer calves. The 205 d-adjusted weaning weight were 226 to 285 kg in bulls and 214 to 252 kg in heifers. The birth weight and hip height at birth were significantly correlated with weaning weight, 205 d-adjusted weaning weight, hip height at weaning and pre-weaning ADG (P < 0.01). Sire group significantly influenced pre-weaning growth performances through interaction with sex of calf. Bull calves from sire group of high growth were 1.0–3.8 kg heavier in birth weight than the bull calves from other sires (P < 0.001). Sire group x sex interaction was significant (P < 0.05) for calf birth weight, 205-d adjusted weaning weight and pre-weaning ADG. Sire group also played a significant role in hip height at birth (P < 0.05). Selections of the sires preferable for growth significantly improved calf pre-weaning growth performances.  相似文献   

16.
The effects of a single challenge with 60,000 infective Ostertagia ostertagi larvae on blood and gastrointestinal mucosal gastrin concentrations, gastrin-producing G-cell numbers in the pyloric mucosa and growth of different parts of the gut were investigated in 16, two-and-a-half-month-old calves. Infected calves exhibited a rise in abomasal pH which was accompanied by a 145 per cent increase in wet weight of the fundic mucosa (P<0·05) and a significant rise in blood total gastrin concentrations (P<0·01). Circulating little gastrin (G-17) was unaffected. Pyloric mucosal total gastrin concentrations remained unaltered in the infected calves until day 28 when levels fell to 36·9 per cent of control group values (P<0·01). Pyloric mucosal G-cell numbers declined during the experiment in the infected group. It is suggested that release of previously stored tissue gastrin and not a change in Gcell numbers contributes to the hypergastrinaemia associated with ostertagia infection in the calf.  相似文献   

17.
Multiparous red deer (Cervus elaphus scoticus) hinds (n=17) were either mated to a red deer stag or artificially inseminated with semen from a wapiti bull (C.e. nelsoni) to produce red deer or F1 crossbred (C.e. scoticus × C.e. nelsoni) calves to test the hypotheses that (1) red deer hinds rearing crossbred calves will produce significantly more milk to support calf growth than hinds rearing red deer calves, and (2) hind live weight and body condition may suffer as a result. Hinds and calves were grazed on ryegrass and white clover pastures and supplemented with pasture silage and barley grain when pasture supply was inadequate. Calves were left with their mothers until 9–10 months of age when lactation had terminated naturally. Mean body condition score (BCS) loss was greater in hinds rearing F1 calves than in hinds rearing red calves in the period from late gestation to mid-lactation (September–March, P<0.05). F1 calves grew significantly faster than red deer calves and were heavier at all ages. From February onwards there was a consistent decline in milk intake, and by the latest measurement (22 July) milk production was negligible, and most hinds had ceased lactating. Milk intake by the F1 calves was significantly greater until day 114, after which the measured milk intake was not significantly different. Pasture intake of the F1 calves was significantly greater at day 114 but not at other times (P<0.05). The average hind pasture intake was also not significantly affected by calf genotype when adjusted for post calving hind live weight. The results support the hypothesis that a red deer hind rearing an F1 calf produces significantly more milk than a hind rearing a red deer calf, suggesting that the growth of a red deer calf is limited by its milk demand rather than milk supply by the hind. The study also supported the second hypothesis. Hinds rearing F1 calves exhibited greater losses of body condition score relative to the hinds rearing red deer calves, indicating that the hinds rearing F1 calves were in a greater negative energy balance that hinds rearing red deer calves. This highlights the additional energetic demands on a hind from feeding an F1 calf and in a farmed context the need to ensure that adequate nutrition is provided.  相似文献   

18.
There is an urgent need for knowledge on the effects of alternative housing conditions on parameters of health and production in current food animals, which are usually selected for a prolonged period for production traits. Thus, it is as yet unknown, whether genotype or environmental factors, or both, are major determinants of these traits. Therefore, as a model, the effects of keeping layers in three different types of housing: solitary in battery cages (BC), on a colony basis in a barn provided with litter and perches (BPL) and free range housing with access to the outdoors (FR), respectively, on immune competence and body weight (gain) of chicken lines divergently selected for high (H line) or low (L line) antibody responses to sheep red blood cells (SRBCs), next to a random bred control (C) line were studied. Antibody responses to keyhole limpet haemocyanin (KLH), Escherichia coli lipopolysaccharide (LPS) and ovalbumin (OVA) were significantly higher in the H line as compared to the C and L lines in all three housing systems, whereas in vitro mitogenesis of peripheral blood leukocytes to concanavalin (Con) A, and body weight (BW) were significantly higher in the L line in all three housing systems. No differences between the lines were found with respect to phagocyte activity. Housing conditions affected antibody responses to KLH, i.e. birds kept solitary in BC, and birds kept in BPL systems showed significantly higher antibody responses to KLH, than birds kept in the FR system. Also in vitro T-cell responses to KLH were significantly higher in BC birds than in the FR birds, but T cell responses to Con A were higher in the FR birds. Antibody responses to KLH, but also LPS and OVA were significantly affected by a housing×time interaction. Titers to these three antigens remained at a higher level in the BC then in the FR system. Birds kept in battery cages were heavier, and produced their first eggs approximately 2 and 3 weeks earlier than birds in the BPL and the FR system, respectively. The absence in the present study of significant interactions between line and housing systems on immune competence suggests that regardless of genotype, the animals respond similarly to different environments. The modulation of the magnitude of specific, but not innate immune responses in the three lines by environmental (housing) conditions suggest that the environment may favour types of specific immune responses. In addition, our data suggest that specific genotypes and specific environments may be additive in disease resistance.  相似文献   

19.
October pregnancy rate, calf survival to weaning, weaning age, weaning rate and actual kg of calf weaned/cow exposed were determined in a 4-yr study involving 880 matings of Angus (A), Hereford (H) and Charolais (C) sires to A, H, C and Brown Swiss (BS) dams. Cows were mated in single-sire herds for 45 or 60 d under pasture conditions; heifers were bred to produce their first calf at 3 yr of age. Pregnancy rate of lactating dams was 9.4% higher (P less than .01) than for non-lactating dams. Pregnancy rates for straightbred matings were 87.5%, 80.6% and 75.4%, respectively, for A, H and C groups (P less than .05). No differences (P greater than .10) due to sire breed were found for any of the traits studied except for calf age at weaning. Calves from C sires were younger (P less than .01) at weaning than calves from H and A sires. Breed-of-dam differences (P less than .05 to P less than .01) were found for all traits studied except calf survival rate. All BS dams produced crossbred calves and had lower pregnancy and weaning rates (both P less than .01), calves were younger at weaning (P less than .05), had lower kg of calf weaned/cow exposed (P less than .05) than for beef-breed dams producing crossbred calves. Crossbred calves from BS dams were 4.9, 11.0 and 3.4 d younger (P less than .05 to P less than .01) at weaning, respectively, than crossbred calves from H, A and C dams.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Blood flow rates in ml/100 g tissue/minute to the duodenum, jejunum, ileum and caecum of conscious goats have been measured using radioactive microspheres (15±5 m diameter). The blood flow rates to these various sections of the intestine were significantly higher (P<0·001) under normal conditions than during epinephrine or norepinephrine infusions. Blood flow to the jejunum was also higher than that to the duodenum, ileum or caecum under normal conditions. The differences were found to be significant for duodenum and ileum (P<0·001), while non-significant for caecum (P>0·10).  相似文献   

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