Endocrine and thermal responses to GnRH treatment and prediction of sperm output and viability in holstein-Friesian breeding bulls

A study was conducted to determine changes in serum LH and testosterone concentrations and in scrotal surface temperature (SST; measured with infrared thermography) following GnRH treatment and to predict the number of spermatozoa collected and the proportion that were viable. Holstein-Friesian breeding bulls (n = 22, average age, 24.3 m.o.; range, 15 to 41 m.o.) were examined twice 30 d apart. Concurrently, semen was collected twice weekly with an artificial vagina. Treatment with GnRH (100 micrograms, i.m.) increased (P < 0.0001) serum LH and testosterone concentrations and increased (P < 0.0001) SST (range 0.6 to 1.1 degrees C; P < 0.05) at the top and bottom of the scrotum. In regression models to predict the total number of spermatozoa, significant independent variables included ultrasonic echotexture of the testes (negative slope), scrotal width (positive slope) and SST at the bottom of the scrotum 45 min after GnRH treatment (positive slope). In regression models to predict the percentage of live spermatozoa, ultrasonic echotexture was a significant independent variable (negative slope). Measurement of testicular ultrasonic echotexture and SST after GnRH treatment augmented measurement of testicular size for predicting the number and percentage of live spermatozoa.

Effects of barley variety and processing methods on feedlot steer performance and carcass characteristics

An experiment was conducted to evaluate ammoniation and temper processing of two barley varieties of diverse types on feedlot cattle performance and diet digestibility. Steptoe (feed variety) and Klages (malting variety) barleys were processed as dry-rolled (DR); tempered and rolled (TR); tempered, ammoniated, and rolled (AR); and tempered, ammoniated, and fed whole (AW). Crossbred steers (n = 240, initial weight 266 kg) were blocked by weight and randomly assigned to one of eight treatments in a 2 x 4 factorial arrangement. Diets contained 30% barley (DM basis) for the growing phase and 85% (DM basis) for the finishing phase. Growing phase ADG and gain to feed (G/F) were less (P < .05) for AW than for DR, TR, and AR. Average daily gain was less (P < .05) for AW than for TR and AR in the finishing phase. There were no differences (P > .05) in ADG or G/F between DR, TR, and AR during growing or finishing phases. Gain to feed was greater (P < .05) for TR and AR than for AW but not for DR for the total trial. Hot carcass weight, longissimus muscle area, and kidney-pelvic-heart fat were greater (P < .05) for TR and AR than for AW. Total finishing diet ADF digestibility was greater (P < .05) for Steptoe than for Klages (40.5 vs 31.4%, respectively). The DR treatment had the lowest ADF digestibility, whereas AR had the greatest (P < .05). Results suggest that there were no differences in feedlot steer performance due to barley varieties of the same bulk density and that barley grain must be mechanically processed for optimal performance response rather than ammoniated and fed as whole grain.

Classification of beef calves as protein-deficient or thermally stressed by discriminant analysis of blood constituents

Linear discriminant functions hold promise for identifying either protein-deficient or cold-stressed calves based on blood constituents. For each of 2 yr 60 artificially bred Angus heifers were assigned randomly to a 2 x 2 factorial nutritional plan consisting of .32 or .96 kg/d of maternal CP and 8.7 or 12.2 Mcal/d of ME. The calves from these heifers were assigned randomly to environmental chambers set at either 0 or 21 degrees C in a repeated measures design. Linear discriminant functions were computed for 1 yr (training data) and then used to predict the classification of calves for the other year (validation data). Using the original data, the correct classifications of calves to the protein groups were 96, 80, 60, 59, 54, and 51% for blood samples obtained at 0, 12, 24, 36, 48, and 72 h of age, respectively. Using normalized data, corresponding correct classifications to protein groups were 94, 91, 80, 56, 54, and 52%. Results indicate that protein classification should use blood samples obtained within 12 h of age for reasonable success. For cold-stressed calves, correct classifications using original data were 47 (pre-exposure), 72, 54, 70, 67, and 66% for calves at 0, 12, 24, 36, 48, and 72 h of age, respectively. Corresponding correct classifications using normalized data were 54 (pre-exposure), 74, 70, 72, 69, and 77%. Cold stress could be detected after only 12 h of exposure; the time window for testing was much wider than for protein classification, but the classification generally was less discriminative.

Concentrations of serum constituents in cold-stressed calves from heifers fed inadequate protein and(or) energy

A study with neonatal calves was conducted to determine the effects of maternal crude protein (CP) and(or) metabolizable energy (ME) malnutrition, cold stress (0 or 21 degrees C), and age on concentrations of selected serum constituents. For each of 2 yr, 60 artificially bred Angus heifers were assigned randomly to a 2 x 2 factorial nutritional plan 150 d before predicted parturition. The diets provided each heifer with either .32 or .96 kg/d of CP and 8.7 or 12.6 Mcal/d of ME. Blood samples were obtained from heifers at parturition and from their calves at birth and at 12, 24, 36, 48, and 72 h of age. Sera were analyzed for concentrations of blood urea nitrogen (BUN), creatinine (Creat), iron, total protein (TProt), alkaline phosphatase (AlkPhos), total bilirubin (TBil), and cholesterol (Chol). Mean correlations of these constituents in calf sera between 12-h adjacency intervals were high, but those between longer times (48 or 60 h) were low. Simple correlations of serum constituents between cows and calves at birth were low except for BUN (r = .578 and .295 for yr 1 and 2, respectively). There were significant main treatment effects for maternal CP consumption on BUN levels, for environmental temperature on BUN, Creat, and TBil levels, and for years on BUN, Creat, iron, and AlkPhos levels in calves. Significant polynomial relationships were found over hours of age for all variables. Blood urea N decreased in normal calves but remained relatively constant at a low level in deficient calves. Year x hour of age interactions occurred for iron, TProt, AlkPhos, TBil, and Chol. Protein x year x hour of age interactions were found for iron and Chol. These results suggest that random sampling times are not useful for decision making during the first 72 h after birth. Consideration must be given to multiple samples taken at specific calf ages, to environmental temperatures, and to maternal protein nutritional levels when interpreting calf blood sera data.

Estimation of repeatability of blood constituents in gestating beef cattle on protein- and energy-restricted diets

Repeatabilities of blood constituents were calculated for 104 Angus heifers on two separate experiments fed adequate, protein-deficient, energy-deficient, or both protein- and energy-deficient diets. Four statistical methodologies were compared including analysis of variance, principal component (structural) analysis based on the sample covariance and sample correlation matrix, and maximum likelihood. Of 12 blood constituents tested only seven were considered sufficiently important to be included in the analysis. These blood constituents included blood urea nitrogen (BUN), creatinine (Creat), alkaline phosphatase (Alk Phos), total protein (T Prot), total bilirubin (T Bil), cholesterol (Chol) and Iron (Fe). If the standard linear model assumptions were met for heifers on the adequate diet, the estimators appeared to be quite similar for both years except when the correlation coefficient was relatively small. If the assumption of homogeneity of the variance-covariance matrix (compound symmetry) was relaxed, the structural analysis method based on the sample correlation matrix appeared preferable. However, when combining all diets, the maximum likelihood methodology was preferred. Among the specific blood constituents, Alk Phos had the highest repeatability, not only for the heifers on the adequate diet, but also for heifers on other treatments in both years. Repeatabilities for T Prot appeared to be the most consistent over all rations in both years. Repeatability estimates for Fe were high and relative rankings were consistent for both years, while repeatabilities for the other variables were either low and(or) inconsistent.

Delayed-type skin hypersensitivity and in vitro lymphocyte immunostimulation responses of swine following inoculation with Mycobacterium avium cell walls and a mycobacterial immunopotentiating glycolipid

Miniature swine (n = 5 per group) were inoculated intradermally with mineral oil-in-water emulsions containing either 150 micrograms of mycobacterial immunopotentiating glycolipid P3 (EP3), 150 micrograms of lyophilized Mycobacterium avium (serotype 8) cell walls (E-MaCW), or 150 micrograms P3 and 150 micrograms M. avium cell walls (EP3-MaCW). Swine vaccinated with E-MaCW and EP3-MaCW developed antigen-sensitive lymphocytes detectable with delayed-type hypersensitivity (DTH) skin tests and lymphocyte transformation assays. Swine injected with EP3 were not sensitized. In general EP3-MaCW evoked a more pronounced in vivo DTH tuberculin skin test and in vitro lymphocyte transformation responses than E-MaCW. Time-course studies indicated a more persistent response in swine injected with EP3-MaCW than in those given E-MaCW. Commercial type Yorkshire swine (n = 5) inoculated intradermally with EP3-MaCW developed cell-mediated immune (CMI) responses to avian tuberculin detectable in vivo with delayed-type skin hypersensitivity and in vitro with lymphocyte immunostimulation responses.

Experimentally induced Fasciola hepatica infection in young calves

Twenty-four calves between 1 and 66 days of age (allotted to 3 age groups) were each inoculated with 100 Fasciola hepatica metacercariae to determine their susceptibility to fluke infection. Studies included measuring the immune response, as determined by enzyme-linked immunosorbent assay, fecal egg counts (to evaluate the length of the life cycle between times of metacercariae ingestion and fluke maturation), and the numbers of flukes in the liver of the calves at slaughter. Fasciola hepatica ova started appearing in the feces of calves, all ages, at 60 days after inoculations were done and reached average maximal number by 80 to 90 days. The enzyme-linked immunosorbent assay results indicated that the oldest group of calves had significantly (P less than 0.01) greater antibody concentration from 6 weeks until the 18th to 20th week after inoculation than did the 2 younger groups. At slaughter, calves in the 52- to 66-day age group had mean fluke numbers significantly (P less than 0.01) greater than did calves in the 1- to 27-day and 35- to 44-day age groups.

Heritability of mastitis score in pacific northwest dairy herds

Dairy Herd Improvement Association records of Holsteins in the Pacific Northwest were used to estimate heritabilities and correlations between milk yield, fat yield, fat percentage, and mastitis score. Effects of sire and lactation number were important for all traits except lactation number for fat percentage. Average mastitis score as well as frequency of elevated tests increased with parity. Paternal half-sister analysis showed that heritabilities of milk yield, fat yield, and fat percentage decreased with age averaging .33, .28, and .47 for first records and .29, .20, and .33 for last records. Heritability of mastitis score increased slightly with age averaging .10 for first records and .11 for last records. Milk yield and fat yield showed small genetic correlations of .05 and .07 with mastitis score. Pearson and Spearman correlation coefficients were computed between regressed least square estimates for sires derived for six independent sets of daughters. Pearson correlations between mastitis scores of first and last lactations were .19 and .34, whereas corresponding average Spearman correlations were .11 and .29. These low correlations between sire rankings in different data sets correspond closely with the low heritabilities for mastitis score.

Immunoglobulin levels in serum and colostral whey or protein-metabolisable energy restricted beef cows

Aberdeen Angus cows were fed adequate diets or diets restricted in protein and, or metabolisable energy for the last 156 days of gestation to determine effects of nutritional restriction on concentrations of immunoglobulins in serum and colostral whey. There were no significant interactions between the effects of low protein and metabolisable energy on immunoglobulin concentrations. Thus, observed differences in immunoglobulin concentrations between the restricted and adequate dietary groups were attributed to the main effects of treatment. Low protein or metabolisable energy had little overall effect on serum IgM concentrations although levels began to decrease sooner in gestation in restricted animals than in those fed adequate diets. Concentrations of IgG1 in serum of all animals were similar and a precipitous decrease in concentration was noted at about 240 days of gestation and this decrease continued until parturition. Serum IgG2 concentrations increased in all animals as parturition approached. Immunoglobulin concentrations in colostral whey were either similar to or tended to be slightly higher in dietary restricted animals than in animals fed adequate diets although the differences were not significant.

Serum complement activity of protein-energy malnourished beef cows

Beef heifers were fed protein- or energy-deficient rations (or both) for approximately the last 5 months of pregnancy. Serum samples were periodically collected and were analyzed for amounts of total complement (C) hemolytic activity. After being fed the rations for approximately 2 months, heifers given low-energy rations had significantly lower (P < 0.01) amounts of C than did those fed adequate energy rations, This decrease in C was observed regardless of the amount of dietary protein, although low protein intake seemed to exaggerate the effect of low energy consumption. Reduced protein in the rations had no effect on C titers when caloric intake was adequate. Also, the depressive effect of low dietary energy on C values was no longer apparent after approximately 4 months of feeding the rations. Amounts of C dropped by 20 to 40 U for all groups at or near the time of parturition. The C values averaged over all test dates were significantly lower (P < 0.05) for those heifers given low energy in their rations as compared with values for heifers fed adequate energy rations (146.9 vs 160.8 U).

Effects of maternal protein-energy malnutrition and cold stress on neutrophil function of bovine neonates

The effects of maternal protein or calorie deprivation (or both) on the bactericidal activity of neutrophils and sera from newborn calves subjected to cold stress were studied. Nutritional deficiencies in the dam had little effect on in vitro bactericidal activity of neutrophils and base-line sera taken at birth. Neutrophils obtained at birth destroyed Staphylococcus aureus but not Escherichia coli when incubated with either unheated or heated autologous base-line sera. Heat treatment of base-line sera to inactivate complement did not alter bacterial growth. When incubated in the presence of autologous base-line sera, neutrophils from 3-day-old calves were no more active in the destruction of either bacterium than were neutrophils from newborn calves. However, addition of day 3 (immunoglobulin-containing) sera enabled day 3 neutrophils to destroy E coli (P < 0.0001). The increased destruction of E coli by day 3 neutrophils and day 3 sera was not affected by heat treatment of the sera. Maternal protein deficiency significantly increased (P < 0.05) destruction of E coli by day 3 neutrophils and sera. This effect was independent of energy levels. There were no differences observed in the bactericidal activity of neutrophils and sera taken from calves exposed to 1 C or 21 C environmental chambers for 3 days. Also, cold stress-nutritional stress interactions were not detected.

Digestibility of potato processing residue in beef cattle finishing diets

Two digestion experiments were conducted to determine the effect of various levels of potato processing residue in feedlot diets on digestion of dry matter, gross energy, crude protein and starch. In Exp. 1, 10 Hereford steers (average weight 360 kg) were randomly allotted to one of five diets in which (1) 0, (2) 15, (3) 30, (4) 45 or (5) 60% of diet dry matter was provided by potato processing residue. Potato processing residue was found to be superior to barley as an energy source for beef cattle diets. When fed at 15% of the diet dry matter, potato processing residue had a digestible energy value of 3.68 Mcal/kg, which corresponds to 121% of the digestible energy of barley. However, when the residue was fed at 30, 45, or 60% of the diet dry matter, the mean digestible energy value decreased to 3.10 Mcal/kg, or 102% of the digestible energy of barley. In Exp. 2, four steers (average weight 270 kg) were surgically fitted with permanent ruminal and abomasal T cannulas. The steers were offered one of four diets in which potato processing residue provided (1) 0, (2) 20, (3) 40 or (4) 60% of diet dry matter. Ruminal and postabomasal digestion of dry matter and starch were determined. Inclusion of potato processing residue did not affect (P > .05) the location or extent of digestion of diet dry matter and starch. Diet dry matter and starch digestion in the entire tract were 86.6 and 99.1%, respectively. The mean preabomasal and postabomasal digestions of diet dry matter and starch for all four levels of potato processing residue were 78.7, 20.3, 94.4 and 5.6%, respectively. The site and extent of potato processing residue digestion were comparable to those for barley. Potato processing residue can replace barley as an energy source for finishing beef cattle.

Hemolytic complement levels of neonatal calves delivered from protein-energy malnourished dams and subjected to cold stress

Beef cows were placed on protein-deficient and/or energy deficient rations for the last 150 days of pregnancy. After birth their calves were placed on 1 or 21 C environmental chambers for 3 days, and sera were collected for determination of complement (C) levels. At birth, the mean complement hemolytic (CH50) titer of all calves was 46.0 +/- 1.7 units, but the titer rapidly dropped (P < 0.01) to 31.6 +/- 1.2 by 12 hours after birth. Levels of C activity then began to rise and reached a mean titer of 76.3 +/- 3.0 by 3 days of age. A quadratic curve of predicted CH50 values was constructed from the data. Differences between principal and control groups of calves were not detected. These results suggest that maternal protein-calorie deprivation and limited cold stresses have little effect on levels of C activity in the bovine neonate. Possible explanations for the decrease in CH50 levels after birth are discussed.

Restricted dietary protein in pregnant beef cows: II. Effect on the immune response

Cows fed 0.37 Kg crude protein per day for four months before calving showed no decrease in colostral IgG, IgA, or IgM from cows fed a normal ration. Similarly, no difference in serum immunoglobulin concentration was detected in their calves. Cows in the low protein group developed significantly lower (P < 0.01) titers to Salmonella pullorum antigen than did the normal group. The data show significant positive linear regressions of calf agglutination titer to S. pullorum on the dam's colostral titers. Serum levels of IgG measured at 24 hours were significantly lower in calves from second-calf heifers than from these of other age groups. The IgA levels of serums from calves from the six-year-old cows were significantly higher than the serum levels of calves from younger dams (P < 0.01).

Restricted dietary protein in pregnant beef cows: I. The effect on length of gestation and calfhood mortality

Beef cows fed 0.37 Kg crude protein/day during the last four months of pregnancy had significantly shortened gestation (274 days vs. 282 days) and decreased weight gain (25 Kg vs. 66 Kg) compared to control cows fed 0.96 Kg crude protein/day. Calf mortality in the low protein group was associated with either dystocia (3 calves) or prematurity (2 calves). There were no deaths among control calves. It is suggested that protein malnutrition in late pregnancy may be a contributing factor to neonatal mortality among beef calves.

Classical and alternate complement pathway activities in paired dairy cow--newborn calf sera

Hemolytic assays were used to compare alternate and classical C pathway activities in sera obtained from clinically normal newborn dairy calves and their mothers at the time of delivery. Mean alternate and classical CH50 concentrations in sera from newborn calves were both significantly lower than in their dams (P less than 0.001). The titer of alternate C pathway activity, expressed as CH50 units/ml, in sera from 17 calves was 12.9 +/- 5.5, whereas for the cows it was 25.8 +/- 6.2. The ratio of cow: calf serum alternate CH50 titers averaged 2.25 +/- 0.80 and ranged from 0.88 to 4.14. Classical CH50 titers were 78.0 +/- 42.7 units/ml in calf sera and 246.0 +/- 44.5 in cow sera. The ratio of cow: calf serum classical CH50 titers averaged 3.71 +/- 1.49 and ranged from 1.19 to 6.87. The wide range of values, noted for both the alternate and classical C pathways, within maternal and neonatal groups was assumed to reflect the biologic variability of complement levels in bovine serum. The possible relationships between deficient levels of alternate and classical CH50 activity in newborn calves and their susceptibility to infections is discussed.

Levels of total haemolytic complement activity in paired dairy cow-newborn calf sera

Total haemolytic complement (CH50) activities of sera obtained from newborn dairy calves and their corresponding dams were compared. The differences between the mean maternal and neonatal CH50 concentrations were significant (P less than or equal 0.001). The concentration of CH50 units/ml in sera from 16 calves was 52.0 +/- 21.4, whereas, for the cows it was 195.8 +/- 24.0. The ratio of cow: calf serum CH50 values averaged 4.24 with a range from 1.77 to 8.00. A positive rank correlation of 0.479 (P less than 0.05) was found between the CH50 titres in calves and their dams. Anticomplementary substances were not detected in calf sera. The possible relationships betweeen deficient CH50 levels in newborn calves and their susceptibility to infectious agents is discussed.

Effects of thin ewe syndrome on reproductive efficiency

A debilitating condition affecting mature ewes was found to be associated with the visceral form of caseous lymphadenitis, chronic progressive pneumonia, and Corynebacterium pyogenes infections. The condition was termed thin ewe syndrome. Affected and normal ewes were compared for reproductive efficiency by breed and age; differences in reproductive efficiency between affected and normal Rambouillet and Columbia ewes were highly significant (P less than 0.01). Although not statistically significant, the trend in Targh ee ewes was similar. There was a direct correlation between occurence of the syndrome and increasing age for all breeds.

Ovine campylobacterosis: preliminary studies of the efficacy of the in vitro serum bactericidal test as an assay for the potency of Campylobacter (Vibrio) fetus subsp intestinalis bacterins

An in vitro serum bactericidal test was developed to assess the efficacy of Campylobacter fetus bacterins. Four experimental monovalent bacterins (either serotype C or A-2) and 2 commercial bivalent bacterins (a "suspect" and an "efficacious" bacterin) with aluminum hydroxide adjuvant were administered to sheep and rabbits from which antiserums were then prepared. The different vaccines were evaluated by comparing the in vitro bactericidal activity of the sheep and rabbit antiserums. Results of the in vitro tests were compared to the protection induced in vaccinated ewes which were orally exposed to C fetus. The sheep and the rabbit antiserums after they were heated at 56 C for 30 minutes were unable to exert a killing effect on C fetus cells. Addition of a fresh homologous complement source to the heated antiserums was necessary to demonstrate the in vitro bactericidal capacity. In the comparison of the suspect and the efficacious commercial bacterins, which both reportedly contain serotype C cells, there was a statistically significant difference in bactericidal activities for serotype C cells of antiserums from sheep 14 days after the 2nd vaccination. There was a corresponding significant difference in the antiserums from rabbits 14 days after the 2nd vaccination. Proportionally, more abortions and stillbirths were observed in the ewes vaccinated with the suspect bacterin and then orally exposed to C fetus-serotype C cells than in those vaccinated with the efficacious bacterin. The results indicated that the ability of vaccinated sheep to overcome infection is reflected in the in vitro bactericidal capacity of antiserum from the animal. Since 89% of the variation in sheep antiserums from 14 days after 2nd vaccination can be accounted for by rabbit antiserums from 14 days after 2nd vaccination, the in vitro bactericidal capacity of rabbit antiserums probably provides a reliable index of the protective effect of bacterins containing serotype C for ewes exposed to the homologous serotype.