Fetal growth of beef calves. I. Effect of prepartum dietary crude protein on birth weight, blood metabolites and steroid hormone concentrations

Fifty-nine crossbred heifers (427 kg) bred to one Hereford sire were randomly assigned at 75 d prepartum to two diets. Heifers were individually fed, and diets were isocaloric but contained either a low (LP = 81% NRC, .56 kg/d) or high (HP = 141% NRC, .98 kg/d) level of crude protein. Jugular vein cannulae were inserted into 16 LP and 16 HP heifers at 10 prepartum. Daily preprandial blood samples that were collected until parturition were analyzed for serum estradiol-17 beta (E2), progesterone (P4), glucose (G) and urea nitrogen (UN). Heifers fed LP gained slower than HP-fed heifers before calving (.73 vs 1.02 kg/d; P less than .01); immediate post-calving weights and condition scores were 418 vs 444 kg (P less than .01) and 5.4 vs 6.1 (P less than .01; LP vs HP, respectively). Calf birth weights (35.3 vs 36.1 kg), average calving difficulty score (1.6 vs 1.6) and percent assisted births (35.5 vs 35.7%) did not differ (P greater than .10; LP vs HP, respectively). Prepartum concentrations of UN (6.2 vs 13.5 mg/dl) and G (52.9 vs 58.2 mg/dl) were lower (P less than .05) and P4 (5.94 vs 4.26 ng/ml) was higher (P approximately equal to .07) in LP heifers. Prepartum concentration profiles were related to calving difficulty score (CD, 1 = no assistance to 3 = hard pull) for E2 (CD1 vs CD2 + CD3, P less than .01; CD2 vs CD3, P approximately equal to .01), P4 (CD1 vs CD2 + CD3, P less than .05), G (CD1 vs CD2 + CD3, P less than .05) and UN (CD2 vs CD3, P less than .05). After calving, all dams were maintained together on pasture and supplemented with alfalfa hay and grain mix until adequate range forage was available to maintain weight gains. Dams that were fed LP prepartum gained faster than HP dams during this period (.49 vs .15 kg/d; P less than .01). Prebreeding weights (443 vs 453 kg; LP vs HP) and condition scores (5.1 vs 5.1) did not differ, nor was the postpartum interval affected (44 vs 40 d; LP vs HP). There was no effect of dietary protein on dystocia or postpartum interval, although there were diet-induced differences in body weight and condition of the dams at calving. Results indicate that differences in prepartum profiles of serum steroid hormones and metabolites may be related to dystocia, in addition to relative fetal oversize.     

Sepracell-MN for mononuclear cell separation from cattle: effect on mitogen-and antigen-induced lymphocyte blastogenesis

Mononuclear leukocytes (MNC) were separated from heparinized and EDTA-treated whole bovine blood by centrifugation after mixing with a commercial colloidal silica preparation (Sepracell-MN (S-MN]. Cell yields and lymphocyte blast transformation (LBT) to pokeweed mitogen (PWM), phytohaemagglutinin (PHA), concanavalin A (Con A), and Brucella abortus antigens were tested against MNC obtained from heparinized whole blood using Ficoll-Hypaque (FH). Separation with S-MN was more rapid and less labor intensive than separation with FH. There was a higher average total yield of MNC but a lower percentage of monocytes in the FH- than in the S-MN-separated MNC. In mitogen-induced LBT assays, MNC responded comparably to each mitogen regardless of the separation technique or anticoagulant used, and a cell concentration effect was demonstrated. In general, FH-separated MNC responded greater to PWM than did S-MN/EDTA separated MNC, but S-MN/heparin separated MNC had the greatest LBT responses to PWM. Overall, S-MN/EDTA separated MNC had the greatest responses to PHA, and responses to Con A were variable among experiments with respect to the separation technique. In antigen-induced LBT assays, two B. abortus antigens were used: a heat-killed strain S1119 (HKA) and a gamma-irradiated strain 19 (gamma BA). The LBT responses of three steers vaccinated with live B. abortus strain 19 were compared with three nonvaccinated steers in three separate experiments. Using HKA, FH separation resulted in an overall greater LBT response for vaccinates than nonvaccinates and a greater differential between responses of vaccinates and nonvaccinates than did S-MN derived MNC regardless of the anticoagulant used. Using gamma BA, FH produced the most responsive MNC in one experiment and S-MN/heparin produced the most responsive MNC in the other. At the highest cell concentration tested, FH-separated MNC had the greatest LBT responses for vaccinated calves, but differences between S-MN- and FH-separated MNC responses were not significantly different (P greater than 0.05). In conclusion, S-MN is a rapid and simple technique for separation of MNC from bovine blood. The technique produces an adequate cell population for mitogen-induced LBT studies; however, FH-separated MNC were generally more responsive in the B. abortus-induced LBT assay.     

Delayed T-cell maturation and suppression of mitogen-induced blastogenesis in turkey poults fed cortisone acetate and furazolidone

The effect of cortisone acetate (CA) on the immune response of control and furazolidone (FZ)-fed turkey poults was investigated. CA, fed at a dose of 500 mg/kg of ration beginning at 1 week of age, decreased mortality but had little effect on the development of FZ-induced cardiomyopathy. When poults were 2 weeks of age, the in vitro stimulation of lymphocytes by phytohemagglutinin (PHA) and concanavalin A (Con A) was significantly depressed (P less than or equal to 0.001 and P less than or equal to 0.05, respectively) in cortisone-treated poults. The time of the peak response of lymphocytes from poults 2-5 weeks of age to in vitro stimulation by PHA was significantly delayed (P less than or equal to 0.01) and the magnitude of the response was significantly depressed (P less than or equal to 0.001) in cortisone-treated poults compared with control poults. Cortisone treatment had no effect on time of peak response to Con A stimulation but significantly depressed (P less than or equal to 0.05) the magnitude of the response. Poults receiving FZ administered by gastric tube showed a peak response to PHA stimulation significantly (P less than or equal to 0.05) earlier and significantly (P less than or equal to 0.05) greater than did control poults.     

Adenosine 3',5'-monophosphate in plasma, urine, and native and isoproterenol-stimulated leukocytes of dogs.

Adenosine 3',5'-monophosphate (cAMP) was determined by means of a commercial kit in urine and plasma from 40 hospitalized dogs and in native and isoproternol-stimulated leukocytes from 30 of these animals. Mean urine and plasma concentrations were 6.1 micron and 14 nM, with 95% tolerance limits ("normal values") ranging from 0.0 to 12 micron and 0.21 to 27 nM, respectively. The plasma concentration was approximately half the value previously reported for experimental dogs. The median cAMP content in native leukocytes was 5.9 pmol/10(7) cells. The mean response to isoproterenol was 0.85 pmol/10(7) cells, much less than in human leukocytes. The response was statistically significant (P less than 0.01), but was so small that it is unlikely to be measurably affected in atopic dogs.     

Changes in plasma alpha 1-acid glycoprotein concentration and selected immune response in broiler chickens injected with Escherichia coli lipopolysaccharide

1. Changes in plasma alpha1-acid glycoprotein (AGP) concentration and immune responses following Escherichia coli lipopolysaccharide (LPS) injection were studied in broiler chickens. 2. Higher plasma AGP concentrations were observed from 12 to 48 h after a single injection of LPS. 3. The highest concentration of plasma AGP was observed on day 2 followed by a gradual decrease in chicks injected with 150 mug/kg body weight of LPS every day for 13 d. 4. Plasma AGP concentration in chicks injected daily with LPS at 900 mug/kg body weight for 13 d increased on day 2, and decreased on day 4 to the concentration found before the injection. The concentration increased again on day 10. 5. Changes in plasma interleukin-1 (IL-1) like activity were similar to those in plasma AGP concentration when LPS was injected daily at 900 mug/kg body weight for 3 d. 6. Responses of blood mononuclear cell (MNC) proliferation to mitogen or concanavalin A, (Con A), and pokeweed mitogen (PWM) were positively correlated with changes in plasma AGP concentration. 7. The results suggest that plasma AGP concentration could be used as a positive indicator of changes in blood MNC proliferation to a mitogen and in plasma IL-1 like activity.     

The influence of insulin loading tests per os on insulin and glucose concentrations in blood of piglets within 40 hours from birth

Experiments were conducted to elucidate the time required was showing in what time for postnatal absorption (within 40 hours from birth) and, occurrence of hypoglycaemic activity of exogenous insulin, when high concentrations of the hormone had been present in sow colostrum before parturition, 5 days after parturition, and, occasionally during lactation. The mean insulin concentration in piglet plasma samples from 11 litters amounted to 116.48 pmol/l +/- 101.11 (n = 115), and the glucose concentration was 4.69 pmol/l +/- 1.65 (n = 115), before insulin loading. Oral insulin loading (1.0 I.U./kg body weight) was applied to 10 litters. The piglet litters were separately tested, at different periods, 1, 2, 3, 5, 10, 15, 20, 25, 30, 40 hours after birth. After insulin loading, the mean hormone concentration in plasma samples increased to 447.11 pmol/l +/- 277.01 (n = 83) (P less than 0.001), and the glucose concentration dropped to 2.55 mmol/l +/- 1.08 (n = 83) (P less than 0.001). Insulin absorption from the alimentary tract to blood stopped completely in piglets of litters 10 and 11 examined in 30 and 40 hours after birth. 22 piglets had separated from litters Nos. 4 to 11 and were given intramuscularly injections of 1.0 I.U. insulin. The average hormone concentration in their plasma samples increased to 645.51 pmol/l +/- 44.2 (n = 22) (P less than 0.001), while their average glucose concentration dropped to 2.82 mmol/l +/- 0.13 (n = 22) (P less than 0.001). 24 piglets with hypoglycaemic symptoms from litters orally loaded with insulin and 1 piglet of the intramuscular group, were reanimated by intraperitoneal administration of glucose.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo effects of chloramphenicol, tetracycline, and gentamicin on bovine neutrophil function and morphologic features

Antibiotics that have been shown in vitro to have a detrimental effect on bovine polymorphonuclear leukocytes (PMNL) were injected into the mammary gland. Chloramphenicol, tetracycline, gentamicin, or phosphate-buffered saline solution (PBSS) were administered to uninfected mammary quarters of four cows at recommended doses. Each cow received each of the 4 treatments. Total milk somatic cell count and N-acetyl-beta-D-glucosaminidase activity in milk in response to drug, changes in ultrastructure of PMNL, and effects on in vitro percentage phagocytosis, reduction of nitroblue tetrazolium, and chemiluminescence were studied. Chloramphenicol and tetracycline caused a significant (P less than 0.01) increase in somatic cell count, compared with baseline values. During the first 12 hours, no effect on NAGase activity was observed. All 3 antibiotics caused a significant (P less than 0.05) alteration of PMNL morphologic features. More abnormal PMNL (63%) were found in tetracycline-injected quarters. Gentamicin-injected quarters contained 33% abnormal PMNL, compared with only 5% for PBSS-injected quarters. A significant (P less than 0.01) decrease in percentage phagocytosis was observed for tetracycline and gentamicin. Tetracycline inhibited all chemiluminescence activity, whereas no effect was observed for the other 2 drugs. Nitroblue tetrazolium reduction was nonsignificantly (P greater than or equal to 0.05) decreased for the 3 drugs, compared with that for PBSS controls. On the basis of our findings, we concluded that some antibiotics may be inhibitory to phagocyte function and, thereby, impair host defense mechanisms against invading microbes.     

The effects of adjuvants on immune responses in cattle injected with a Brucella abortus soluble antigen.

Five different adjuvants were examined for potentiation of humoral and cell-mediated immune (CMI) responses in cattle to a Brucella abortus soluble antigen (BASA). Two separate experiments were performed involving a total of 64 steers, divided among six groups (Experiment 1) and 9 groups (Experiment 2). The adjuvants used were: muramyl dipeptide, Freund's incomplete adjuvant, dimethyl-dioctadecyl ammonium bromide (DDA), Bordetella pertussis and Propionibacterium acnes. In each experiment, three groups received BASA (2 mg protein) subcutaneously with adjuvant, one group received a reduced dose of B. abortus Strain 19 (S19), one group served as unvaccinated controls, and another group received BASA alone. Primary responses were studied following a single immunization in comparison to the single inoculation with S19. For each experiment serum antibody responses and CMI responses were sequentially determined over a period of 56 days. Antibody responses to B. abortus were measured using the brucellosis card, rivanol precipitation-plate agglutination, complement fixation, and fluorometric immunoassay tests, and as well as with an enzyme-linked immunosorbent assay. The CMI response was measured using antigen-specific lymphoproliferation (LP) and skin testing for delayed-type hypersensitivity (DTH) to BASA (Experiment 2). Specific aspects of induced CMI responses investigated were macrophage activation (IL-1 production), helper T cell activation (IL-2 production), and release of soluble suppressor factor(s). In general, mean antibody responses were significantly higher (P less than 0.05) in immunized steers than in control steers and those receiving BASA alone. The LP responses to heat-killed B. abortus were generally higher in immunized groups than in the controls. The LP and DTH responses were greatest in the groups receiving S19 and BASA + DDA. Increased induction of IL-1 was largest in the group receiving BASA + DDA whereas IL-2 release was greatest in S19 vaccinated steers. Suppressor T cell responses were most obvious in the groups receiving S19, BASA + B. pertussis, and P. acnes. These studies demonstrated that DDA potentiates CMI responses to a soluble B. abortus antigen and may be useful as an adjuvant for future vaccines, particularly subunit vaccines.     

Comparison of urinary protein concentration and protein/creatinine ratio vs routine microscopy in urinalysis of dogs: 500 cases (1987-1988)

The clinical problems and results of urinalyses of 500 dogs were reviewed and summarized to compare the sensitivities for detection of abnormalities indicative of urinary system disease among qualitative (sulfosalicylic acid [SSA]), quantitative (Coomassie brilliant blue [CBB]), and indexed (urinary protein/creatinine ratio [U(P/C)]) determinations of urinary protein loss vs microscopic examination of urine sediment. False-negative rates for the detection of microscopically abnormal urine specimens were 5.4% for SSA greater than or equal to 1+, 8.5% for CBB greater than or equal to 1.0 mg/ml, 9.7% for U(P/C) greater than or equal to 1.0, and 7.7% for CBB + U(P/C). A discriminatory U(P/C) value of 2.0 would have excluded dogs with clinically relevant proteinuria in the lower ranges. Proteinuria was not detected in 4.4% (22/500) of the specimens in which important numbers of leukocytes or bacteria were observed. False-negative rates for combined interpretation of quantitative protein concentration and U(P/C) were not significantly different (P greater than 0.10) from SSA alone. Degrees of azotemia were higher (high serum creatinine concentration, P greater than 0.10 and high serum urea nitrogen concentration, P less than 0.05) and prevalence of chronically diseased dogs was greater (P less than 0.005) in dog categories with higher U(P/C) values. More quantitative determinations of urinary protein loss as a screening test offer potential labor-saving and diagnostic advantages in the identification of urinary disease over more qualitative routine screening methods.     

刈割期及添加剂对苜蓿青贮品质及CNCPS蛋白组分的影响

本试验旨在研究生物及化学添加剂对不同时期刈割的苜蓿青贮品质的影响。试验采用现蕾期和初花期刈割的中苜一号苜蓿(70%水分含量)为原料,分别设置添加:1)空白组;2)乳酸菌+纤维素酶(10⁵cfu/g+50 mg/kg);3)乳酸菌+纤维素酶(10⁵cfu/g+100 mg/kg);4)甲酸+丙酸(6 mL/kg)4个处理组,使用0.5 L塑料桶调制罐装青贮,并于发酵30 d后开罐取样分析。结果表明,与现蕾期相比,初花期苜蓿青贮饲料的乳酸(LA)产量较高,丁酸(BA)和氨态氮(NH3-N)生成量较低(P<0.01),pH值也较低(P<0.05),同时非蛋白氮(PA)和结合蛋白质(PC)含量也显著低于现蕾期(P<0.01)。3个添加剂处理组均显著地提高了青贮发酵的品质,降低pH值(P<0.01)和氨态氮生成量(P<0.01)。其中,乳酸菌+纤维素酶显著地提高了乳酸含量及乳酸/乙酸(LA/AA)(P<0.01),甲酸+丙酸则显著抑制了丁酸的产生(P<0.01)。同时,3组添加剂均显著地提高了青贮饲料中可溶性碳水化合物(WSC)和粗蛋白(CP)的含量,并降低了中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的含量(P<0.01)。就蛋白组分而言,乳酸菌+纤维素酶(10⁵ cfu/g+100 mg/kg)和甲酸+丙酸处理组显著地降低了青贮饲料中非蛋白氮和结合蛋白质的含量(P<0.01),提高了真蛋白(PB)的含量(P<0.01)。综合而言,甲酸+丙酸处理组苜蓿青贮料的品质最佳,乳酸菌+纤维素酶(10⁵ cfu/g+100 mg/kg)次之。     

Determination of phagocytosis of 32P-labeled Staphylococcus aureus by bovine polymorphonuclear leukocytes

A procedure for the measurement of phagocytosis by bovine polymorphonuclear leukocytes (PMN) of 32P-labeled Staphylococcus aureus was modified so that a larger number of samples could be compared in a single run, and smaller volumes of sample, PMN, and 32P-labeled S aureus could be used. Results were highly reproducible, with a coefficient of variation between duplicate determinations of less than or equal to 2%. Lysostaphin was prepared from the supernatant of S staphylolyticus and was compared with a commercially available preparation. Effects of lysostaphin on PMN and influence of incubation media on release of 32P from 32P-labeled S aureus by lysostaphin were examined.     

Urinary aquaporin-2 excretion in dogs: a marker for collecting duct responsiveness to vasopressin

In humans, the urinary aquaporin-2 (U-AQP2) excretion closely parallels changes in vasopressin (VP) action and has been proposed as a marker for collecting duct responsiveness to VP. This report describes the development of a radioimmunoassay for the measurement of U-AQP2 excretion in dogs. In addition, the localization of AQP2 in the canine kidney was investigated by immunohistochemistry. Basal U-AQP2 excretion was highly variable among healthy dogs. Two hours after oral water loading, the mean U-AQP2/creatinine ratio decreased significantly from (231 +/- 30) x 10(-9) to (60 +/- 15) x 10(-9) (P = 0.01), while the median plasma VP concentration decreased from 4.2 pmol/l (range 2.2-4.8 pmol/l) to 1.2 pmol/l (range 1.0-1.9 pmol/l). Subsequent intravenous administration of desmopressin led to a significantly increased mean U-AQP2/creatinine ratio of (258 +/- 56) x 10(-9) (P = 0.01). Two hours of intravenous hypertonic saline infusion (20% NaCl, 0.03 ml/kg body weight/min) significantly increased the mean U-AQP2/creatinine ratio from (86 +/- 6) x 10(-9) to (145 +/- 23) x 10(-9) (P = 0.045), while the median plasma VP concentration increased significantly from 2.2 pmol/l (range 1.1-6.3 pmol/l) to 17.1 pmol/l (range 8.4-67 pmol/l) (P < 0.001). Immunohistochemistry revealed extensive labeling for AQP2 in the kidney collecting duct cells, predominantly localized in the apical and subapical region. As in humans, U-AQP2 excretion in dogs closely reflects changes in VP exposure. Urinary AQP2 excretion may become a diagnostic tool in dogs for the differentiation of polyuric conditions such as (partial) central or nephrogenic diabetes insipidus, primary polydipsia, and inappropriate VP release.     

Influence of high phosphorus intake on salivary and plasma concentrations,and urinary phosphorus excretion in mature ponies

This study addressed the question whether the concentration of phosphorus (P) in saliva of ponies is influenced by P intake. Six ponies were fed a diet high in P (HP treatment), providing 21 g P/day, and a diet low in P (LP treatment), supplying 7 g P/day. The two diets provided approximately 21 g calcium (Ca) and 6 g magnesium (Mg)/day. The experiment had an A‐B‐A design with treatment periods of 30 days. The ponies first received the HP diet (HP1), followed by the LP treatment and were then fed again the HP diet (HP2). Urinary P excretion was increased in both HP feeding periods and equalled approximately 7% of P intake vs. 0.5% on the LP diet. Plasma P concentration was higher for the HP treatment. The salivary P concentration ranged from 0 to 1.01 mmol P/l between ponies and there was no effect of P intake. It is suggested that saliva is not an important excretion route of P. The percentage of Ca and Mg in urine (% of intake) was higher for the LP treatment than for the HP treatments. The results of this study suggest that salivary Mg may contribute to Mg homeostasis.     

Effect of dietary protein level on nitrogen metabolism in lambs: studies using 15N-nitrogen

Six wether lambs (31 kg) were randomly assigned to two treatments (three lambs/treatment): a high protein intake (HP; 21 g N/d) or a low protein intake (LP; 12 g N/d). Each lamb received 860 g/d dry matter (DM) of a pelleted diet (75% corn-soybean meal, 25% cottonseed hulls) offered hourly in 24 equal portions. Single injections of 15N-labelled compounds were made into the ruminal NH3-N and blood urea-N pools to measure the rate of flux through, and transfer of N between, these and the bacterial N pool. Total tract digestibilities of DM and N were lower (P less than .05) for the LP than the HP treatment. Abomasal flows of total, feed or bacterial N tended to be greater (P greater than .05) in lambs fed HP than LP. Lambs fed HP excreted more (P less than .01) urinary N, yet retained a greater (P less than .01) amount of N than lambs fed LP (6.2 vs 1.8 and 9.7 vs 4.1 g N/d, respectively). Pool size and production rate for both ruminal NH3-N and blood urea-N were greater (P less than .05) for the HP than LP treatment. Lambs consuming HP degraded more (P less than .05) blood urea-N in the gastro-intestinal tract (13.4 vs 6.9 g N/d); however, lambs fed LP degraded a greater (P less than .05) percentage of synthesized body urea-N (88.7 vs 71.8%). Ruminal NH3-N absorption was greater (P less than .01) for the HP than LP treatment (3.1 vs .5 g N/d). Although the percentage of bacterial N derived from ruminal NH3-N was similar (P greater than .05) between diets (51.1 vs 63.9), a greater (P less than .05) percentage of bacterial N was derived from blood urea-N in lambs fed LP than HP (77.1 vs 30.2%). Lambs fed LP incorporated a greater (P less than .10) amount of blood urea-N into bacterial N than lambs fed HP (5.5 vs 2.6 g N/d). These data are interpreted to suggest that blood urea-N may provide a substantial quantity of N for bacterial protein synthesis and, thus, may be an important source of protein in the deficient animal. In addition, urea recycling may play an important role in the recovery of ruminal NH3-N lost through absorption in animals fed a high level of protein.     

Suppression of cell-mediated immunity by purified aflatoxin B1 in broiler chicks

The effect of purified aflatoxin B1 on cell-mediated immunity (CMI) in broiler chicks was assessed using doses of 0.3 and 1 mg/kg feed from hatching to 6 weeks of age. Total lymphocyte and T lymphocyte counts and the 2,4-dinitrofluorobenzene skin sensitivity test, graft-versus-host reaction and nitroblue tetrazolium salt reduction tests were used to evaluate CMI. Both doses of aflatoxin B1, including the apparently nontoxic dose of 0.3 mg/kg feed, caused a significant (P less than 0.05) decline in CMI. The functional activity of splenic macrophages was decreased significantly (P less than 0.05) by both doses of the toxin.     

Efficacy of laidlomycin propionate in low-protein diets fed to growing beef steers: effects on steer performance and ruminal nitrogen metabolism

We conducted two experiments to evaluate the effect of the ionophore laidlomycin propionate (LP) on steer performance and ruminal N metabolism. Experiment 1 was a 91-d growth study evaluating the growth and ruminal characteristics of steer calves consuming supplemental LP. Steers (n = 96; 255 +/- 3 kg; four steers/pen; six pens/treatment) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments consisting of two levels of dietary CP (formulated to be 10.5 and 12.5% of DM) with and without LP (11 mg/kg diet DM). Ruminal fluid was collected via stomach tube on d 91 from one steer randomly selected from each pen. No CP x LP interactions were observed with performance data (P > .64). Final weight and total gain were greater (P < .07) for 12.5% CP and LP compared with 10.5% CP and control steers, respectively. Also, DMI was increased (P = .08) with 12.5% CP but not with LP supplementation (P = .36). In addition, ADG and gain:feed ratio were greater (P < .03) for both 12.5% CP and supplemental LP. Ruminal NH3 N concentration was greater (P < .09) with 12.5% CP and LP. Total VFA concentration and molar proportion of acetate were not affected by treatment (P > .11). However, propionate concentration was increased (P < .09) with 12.5% CP and LP, and acetate:propionate was lower (P = .02) with LP supplementation. In Exp. 2, six steers were used in a replicated 3 x 3 Latin square design to compare ruminal fermentation and protein degradation in steers without ionophore feeding or adapted to LP or monensin. In vitro deamination of amino acids by adapted ruminal microbes was also assessed. Ionophore supplementation decreased (P = .07) ruminal NH3 N concentration compared with control steers, and LP increased (P = .02) ruminal NH3 N compared with monensin. Molar proportion of acetate was decreased (P = .02) and propionate increased (P = .01) with ionophore treatment. Consequently, ionophore supplementation depressed the acetate:propionate ratio (P = .01). In situ degradation rate of soybean meal (SBM) CP was greater (P = .09) with ionophore treatment, but estimates of SBM undegradable intake protein were not altered by treatment (P > .25). Microbial specific activity of net NH3 N release and alpha-amino N degradation were decreased (P < .04) with ionophores. Based on this study, LP and monensin did not affect the extent of ruminal degradation of SBM CP but decreased amino acid deamination.     

Effects of early- to mid-gestational undernutrition with or without protein supplementation on offspring growth, carcass characteristics, and adipocyte size in beef cattle

Angus × Gelbvieh cows with 2 to 3 previous pregnancies were used to evaluate effects of maternal nutrient restriction on offspring adipose tissue morphology at standard production endpoints. At 45 d after AI to a single sire, pregnancy was confirmed and cows randomly allotted into groups and fed a control (Con, 100% of NRC recommendations), nutrient-restricted (NR, 70% of Con diet), or nutrient-restricted + protein-supplemented (NRP, 70% of Con + essential AA supply to the small intestine equal to Con) diet. At d 185 of gestation, cows were commingled and received the Con diet thereafter. Bull calves were castrated at 2 mo of age. Calves were weaned at 210 d, backgrounded for 28 d, and then placed in the feedlot for 195 d. Steers and heifers were slaughtered at an average 12th-rib fat thickness of 7.6 mm. Adipose tissue from selected depots was collected for adipocyte size analysis. There was no significant difference in BW or BCS between Con, NRP, and NR cows at d 45 of gestation, which averaged 489.7 ± 17.7 kg and 5.35 ± 0.13, respectively. At d 185 of gestation, Con and NRP groups had similar BW (566.1 ± 14.8 and 550.2 ± 14.8 kg) and BCS (6.34 ± 0.27 and 5.59 ± 0.27), but NR cows exhibited reduced (P < 0.05) BW (517.9 ± 14.8 kg) and BCS (4.81 ± 0.27). Among offspring (steers and heifers) at slaughter, there were no significant differences in BW or organ weights among treatment groups. Yield grade was reduced (P < 0.05) and semitendinosus weight/HCW tended (P = 0.09) to be reduced in NR offspring compared with Con and NRP offspring. Average adipocyte diameter was increased (P < 0.05) in subcutaneous, mesenteric, and omental adipose tissue and tended (P = 0.09) to increase in perirenal adipose tissue in NR compared with Con offspring with NRP offspring adipocyte diameter being either intermediate or similar to Con calves. The adipocyte size alterations observed in NR offspring were confirmed by DNA concentration of the adipose tissue depots. There also was an increased mRNA expression (P < 0.05) of fatty acid transporter 1 in subcutaneous adipose tissue from NR offspring compared with Con and NRP offspring. Nutritional restriction during early and mid gestation increased or tended to increase (P < 0.09) adipocyte diameter in all adipose tissue depots in finished steer and heifer calves.     

Venous blood pressure relative to the development of bovine udder edema

Cranial superficial epigastric (milk vein) and jugular venous blood pressure were measured in 8 cows with udder edema and in 3 normal control cows at least 2 weeks before parturition, at parturition, and 2 weeks after parturition. Cows with udder edema had a significant mean increase (P less than or equal to 0.05) in cranial superficial epigastric venous pressure at parturition when compared with pressures 2 weeks prepartum and 2 weeks postpartum. Unaffected control cows had an insignificant increase in cranial superficial epigastric venous pressure during these 3 periods of measurement. There was an insignificant increase in jugular venous blood pressure during the 3 periods of measurement in affected and control cows. A correlation was observed between mammary blood flow and cranial superficial epigastric blood pressure at parturition (r = -0.659, P less than or equal to 0.05).     

Effect of selenium deficiency on caprine polymorphonuclear leukocyte production of leukotriene B4 and its neutrophil chemotactic activity

These studies were designed to measure leukotriene B4 (LTB4) production by polymorphonuclear leukocytes (PMN) from selenium (Se)-deficient and Se-adequate goats. Leukotriene B4 was measured by both radioimmune and chemotactic activity assays in supernatants of PMN stimulated by calcium ionophore A23187. The concentration of LTB4 produced by PMN from Se-deficient goats was significantly (P less than 0.05) lower than the concentration of LTB4 produced by PMN from Se-adequate goats. Neutrophil chemotactic activity of LTB4 was found to be directly dependent (r2 = 0.85) on the LTB4 concentration. When supernatants from Se-deficient and Se-adequate goats were adsorbed with caprine neutrophils, significant (P less than 0.05) reduction in LTB4 was found in supernatants from both groups. Furthermore, neutrophil adsorption of LTB4 from supernatants of both groups was indicated by significantly (P less than 0.05) decreased chemotaxis to LTB4 supernatants. Decrease in chemotactic response was, however, significantly (P less than 0.05) lower when neutrophils were treated with supernatants from Se-deficient goats. These results indicate that Se deficiency decreases the production of LTB4 by caprine PMN and, hence, LTB4-mediated neutrophil chemotaxis.     

Hormonal interrelationships in postpartum suckled dairy cows.

Three cross-bred cows calved in March and April and were followed until day 62 after parturition. Each animal was suckled by 2 calves ad libitum. All calves were removed from the cows on day 55 after parturition. Blood was collected 3 times per day from the jugular vein by venipuncture. On 4 occasions after parturition--i.e. days 7-8, 21-22, 35-36 and 49-50, the cows were bled through a jugular venous catheter every 30 min during the 24 h. The plasma samples were analyzed for the content of 15-keto-13,14-dihydro-PGF2 alpha (main PGF2 alpha metabolite), LH, prolactin, cortisol and progesterone by radioimmunoassay methods. The concentration of PGF2 alpha increased from 280 to 730 pmol/l within the last 4 days before parturition. The highest geometric mean was 3106 pmol/l on the day of parturition. Thereafter a steady decrease of PGF2 alpha metabolite concentration was seen until day 21 when it reached plateau at 148 pmol/l. In all cows plasma LH concentrations increased significantly (P < 0.05) from about 1.6 micrograms/l on days 7-8 to 2.4 micrograms/l on days 21-22 post partum. The frequency of LH pulses showed no tendency to increase as the postpartum period progressed and averaged 6.5 pulses/24 h. Mean plasma LH concentrations increased from 2.1 micrograms/l 2 days before weaning to 3.2 micrograms/l 2 days after weaning (P < 0.05). LH peaks occurred less frequently in association with prolactin and cortisol peaks than in their absence. A partial positive correlation between PGF2 alpha metabolite and cortisol (r = 0.30) was found on days 7-8 post partum. Correlation between prolactin and cortisol on days 7-8 and 21-22 post partum was also positive (r = 0.20 and r = 0.27, respectively). There was a negative correlation between LH and cortisol on days 7-8 (r = -0.27) and days 49-50 (r = -0.21) post partum. The first and short progesterone increase observed after weaning was terminated in conjunction with PGF2 alpha metabolite peaks.