Showing papers in "Journal of Animal Science in 1985"

Cow Type and the Nutritional Environment: Nutritional Aspects

Abstract: Numerous studies have been reported that relate to the influence of cattle type on production efficiency; however, most reported studies have been concerned with output characteristics. This review concentrates on the influence of cattle type on the input requirements and more specifically, energy requirements. Data are presented that show that energy is required for maintenance, growth, gestation and lactation and requirements for each of these functions vary among cattle types. Data are presented that suggest 70 to 75% of total annual energy requirements are required for maintenance functions and variation in requirements for maintenance appear to be greater than variation in requirements for growth, gestation or lactation. In general, variation in maintenance requirements appears to be positively associated with genetic potential for measures of production, e.g., rate of growth or milk production. Reported results suggest that animals having genetic potential for high productivity may have less advantage or be at a disadvantage in a more restrictive environment, suggesting the need for synchronization of production environment and germ plasm resources. Some of the sources of variation in maintenance requirements have been discussed. Data are cited that suggest little of the variation in maintenance energy expenditures is attributable to variation in total body composition per se. However, considerable evidence has accumulated to show that a relatively large proportion of maintenance energy expenditures can be attributed to energy expenditures of visceral organs, especially the liver and gastrointestinal tract. High rates of energy expenditures of these tissues appear to be directly or indirectly associated with the high rates of protein synthesis in these tissues. Greater use of differing research approaches and assimilation of the results are needed to develop an understanding of the reasons for variation among animals in maintenance energy expenditures or energetic efficiency.

Stimulation of Swine Growth by Porcine Growth Hormone

Abstract: Highly purified porcine growth hormone (pGH; USDA-B1) was administered by im injection (22 micrograms X kg body weight-1 X d-1) to rapidly growing Yorkshire barrows for 30 d. Growth hormone significantly increased growth rate (10%), feed efficiency (4%), cartilage growth and muscle mass. However, pGH did not affect carcass adipose tissue mass. Intramuscular lipid content of the longissimus was increased 50% by pGH administration. Plasma pGH concentration was elevated (7- to 11-fold) for 3 to 5 h post-injection. Chronic administration of pGH depressed pituitary GH content and concentration approximately 45%. No GH antibodies were detected in the plasma of GH-treated swine. Plasma somatomedin-C concentration was increased 55% by GH treatment 3 h post-injection. Plasma glucose and insulin concentrations were both significantly increased in GH-treated swine, suggesting that the animals had developed a state of insulin resistance. Plasma-free fatty acid concentration tended to be higher in GH-treated animals. Treatment of swine with pGH significantly decreased plasma blood urea nitrogen. Assessment of animal health during the trial and postmortem indicated that pGH administration did not have any adverse effects. In summary, treatment of young, rapidly growing swine with pGH stimulated growth performance without affecting animal health or inducing the production of GH antibodies.

Adipose Tissue Growth and Cellularity: Changes in Bovine Adipocyte Size and Number

Abstract: Forty crossbred steers of similar birth date and fed the same growing-finishing diet were used to study adipocyte changes in six fat depots during growth from 11 to 19 mo of age. Steers were slaughtered at 2-mo intervals. Adipose tissue samples were obtained from kidney, mesenteric and brisket fat and subcutaneous, intermuscular and intramuscular fat from the 10th to 12th rib section. The osmium tetroxide fixation technique was used for determination of cell size and number. Except for three brisket fat samples, distributions of adipocyte diameters from six different fat depots were monophasic during the age range considered in this study. At 17 mo of age, the mean adipocyte diameter, in decreasing order, was: kidney fat greater than mesenteric greater than subcutaneous greater than intermuscular greater than intramuscular greater than brisket fat. Fat deposition during growth to 19 mo of age occurred mainly by hypertrophy of adipocytes. An apparent cell hyperplasia occurred in the intramuscular fat depot from 11 to 15 mo and in the brisket fat depot after 15 mo of age. Based on cellularity characteristics, evidence exists to classify intramuscular and brisket fat depots as late-developing ones. Cell number/gram of intramuscular adipose tissue was a better predictor of marbling score than was fat cell diameter.

A Quantitative Ethogram of Aggressive and Submissive Behaviors in Recently Regrouped Pigs

Abstract: Twenty prepubertal Yorkshire X Hampshire pigs were mixed in groups of four. Their behaviors were recorded on video tape for 48 h, and a detailed behavioral analysis was performed. Aggressive interactions of 10 unique pairs of pigs were observed. Twenty-five distinct behavioral categories were identified in the total data set, which contained 1,846 behaviors. On average, an interacting pair showed 92 behavioral elements (range: 10 to 307). Eighty-one percent of the behaviors observed consisted of bites and pushes given and received. Bites were targeted mainly at the ears (55%), face (17%) and neck (23%). Most bites to the rump and turning the body 180 degrees occurred during the last third of the fight. Pigs that eventually won fights showed higher incidences of ear bites and lower incidences than expected of head-under-head pushing and body-turning. Pigs that lost fights showed higher frequencies of head-under-head pushing and body-turning. Losers also showed a lower frequency of rump biting. Overall, many of the behaviors performed by the losing pigs were followed by the loser receiving an ear bite. Body-turning was a sign of submission and was always preceded by, and often followed, ear-biting. Once a pig showed body-turning, it generally avoided further face-to-face interaction. Behaviors exhibited as signs of submission were found in each of the 10 pairs observed.

Estimates of genetic correlations between testicular measurements and female reproductive traits in cattle.

Abstract: Data from 528 male and 645 female progeny of 63 sires were used to estimate genetic correlations between female and male reproductive traits. Data were from two Hereford herds involved in a long-term selection program of the North Carolina Agricultural Experiment Service. Testicular measurements of circumference, diameter, length and volume were obtained on bulls at 205 and 365 d. Testicular growth measures were defined as differences between 205-and 365-d measurements. Heifers were placed in the breeding herd as yearlings and given two breeding seasons to produce a calf. Traits utilized from females were three age-at-first-breeding traits, two age-at-first-calving traits, two pregnancy rate traits, rebreeding interval and calving interval. Genetic correlations were estimated from half-sib and from sire-daughter analyses. Seventy-five percent or more of the correlations of testicular measurements with pregnancy rats, age at first breeding and age at first calving were in the favorable direction. Average correlations were .62, -.55 and -.66, respectively. For each of the remaining female traits, approximately 50% of the correlations were favorable and the average correlations were small. Correlations were summarized by testicular measurement with favorable correlations given a negative sign. Testicular diameter had more favorable correlations (80%) than length, volume or circumference (70%). However, average correlations were similar (-.31, -.30, -.34 and -.26, respectively). Testicular measurements taken at either 205 or 365 d had the same percentage of favorable correlations (72%), while testicular growth measurements had a slightly higher percentage of favorable correlations (78%). Average correlations of 365-d measures were higher (-.38) than either 205-d or growth measures (-.25 and -.28, respectively). Heritabilities for testicular measurements tended to be moderate to high, while those for female reproduction tended to be low to moderate. These results suggest that selection for increased testicular size would lead to improvement in female reproduction, particularly an increase in calving rate and a decrease in age at first breeding.

Behavior and Performance of Weanling Pigs in Pens Equipped with Hide Areas

Abstract: Two-hundred eighty crossbred pigs were used to determine the efficacy of hide areas (hides) in reducing young pigs' aggressive activity during social stress and the effect of access to hides on young pigs' productive performance. In Exp. 1, 80 pigs were kept in littermate groups of five/pen in 16 home pens. Then one pig was randomly selected from each of four pens, and the four were regrouped in either a control pen or a pen equipped with three hides (each a 20 X 23 X 25 cm box) in one of the walls. Behavior was time-lapse video-recorded for 90 min. Time spent either eating (head-in-feeder) or lying was not affected by access to hides. Pigs with hides to use in escaping attack fought less during the initial 30 min after regrouping. They spent an average of 5.5% of the time with heads hidden during the entire 90-min observation period. Experiment 2 employed 200 pigs in a performance study designed to evaluate effects of regrouping and access to hides on body weight gain and feed conversion efficiency. There were 10 replicates of each of four treatments: (a) regrouped-control pen, (b) regrouped-hide pen, (c) littermates-control pen and (d) littermates-hide pen. During the first 7 d of the 21-d trial, treatments tended to interact in affecting both average daily gain and feed conversion efficiency; littermates in control pens had the highest performance, those regrouped in hide pens were intermediate and those in regrouped-control pen and littermates-hide pen treatment groups had the poorest performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Sources of variation and prospects for improvement of productive efficiency in the dairy cow: a review.

Abstract: In this review, "productive efficiency" in dairy cows is defined as the yield of milk obtained in ratio to the nutritional costs associated with maintenance, milk synthesis and loss of body condition during lactation Improvements in efficiency could occur as a result of changes in digestion and nutrient absorption, maintenance requirement, utilization of metabolizable energy for production or nutrient partitioning Digestibility can be greatly enhanced by appropriate dietary manipulation Likewise, it may be possible to reduce maintenance requirements and improve the efficiency with which metabolizable energy is used for milk synthesis by manipulation of the pattern of nutrients presented to tissues However, these factors apparently do not respond to selection for increased milk yield, and little variation is observed among cows In contrast, individual cows differ substantially in feed intake and in the partitioning of nutrients among body tissues Techniques associated with genetic engineering and the early prediction of genetic merit have the potential to improve productive efficiency by manipulation of these processes However, changes in nutrient partitioning and feed intake during lactation are coordinated by a complex network of controls that accommodate the nutrient requirements of each tissue while maintaining homeostatic balance Future improvements in productive efficiency will therefore depend on our ability to understand the manner in which these controls operate

Effect of the beta-adrenergic agonist cimaterol (CL 263,780) on the growth and carcass characteristics of finishing swine.

Abstract: A randomized complete-block design was used to evaluate the effects of the beta-adrenergic agonist, cimaterol (CL 263,780), on growth rate, feed efficiency and carcass composition of finishing swine. The drug was fed at four levels (0, .25, .5 and 1.0 ppm) to a total of 240 pigs from 64.5 to 103.7 kg live weight. Growth rate and feed efficiency were measured during the 7-wk feeding trial. Feeding cimaterol depressed feed intake, improved feed efficiency and did not alter rate of gain. Carcass evaluation showed that pigs continuously fed cimaterol had 13.2, 9.3 and 9.2% less fat measured at the 10th rib, P2 and average backfat (BF) locations, respectively, compared with controls. Cimaterol-fed pigs had increased loin eye areas (10.9%), and increased semitendinosus (11.8%) and biceps femoris (8.9%) weights compared with controls. The semitendinosus muscles of the cimaterol-fed pigs had less fat and the femur bones were shorter and lighter weight than controls. There were no detected differences in structural soundness of the live pigs, but postmortem evaluation of the hooves indicated that pigs fed 1.0 ppm cimaterol had a higher incidence of hoof lesions. Pigs withdrawn from cimaterol for 7 d were comparable in performance and carcass characteristics with those continuously fed the drug except that carcass fat measurements had generally returned to control values. The data indicate that cimaterol improved the feed efficiency of finishing pigs and increased the lean:fat ratio of their carcasses. Withdrawal of cimaterol caused compensatory fat deposition.

Net portal absorption of lactate and volatile fatty acids in steers experiencing glucose-induced acidosis or fed a 70% concentrate diet ad libitum.

Abstract: Five crossbred steers (347 kg) were surgically fitted with rumen fistulae, hepatic portal, abdominal aorta and mesenteric catheters to measure organic acid absorption from the gut during acute [intraruminal glucose, 12 g/kg body weight (G)] or subacute [ad libitum 70% concentrate diet (C)] acidosis. Samples were taken at time 0, then every 2 h for 48 h after a switch from an alfalfa diet to C, or dosing with G. Steers receiving C received G 1 wk later so that five steers provided four observations/treatment. Blood flow rates were determined by infusion of para-amino hippuric acid (PAH) and averaged 767.8 and 712.5 liters/h for C and G, respectively. Animals consuming C averaged 13.6 kg dry matter from 0 to 24 h and 1.5 kg from 24 to 48 h. Rumen pH declined to 4.2 for G compared with 6.0 for C. Blood pH and HCO3 showed only slight depressions for G from 16 to 26 h, the period of lowest rumen pH. Rumen L-lactate concentration averaged 53.4 mM (peak 77 mM) and 2.1 mM for G and C, respectively. Rumen D-lactate concentration averaged 30.2 mM (peak 47 mM) for G and 1.2 mM for C. Net portal absorption of L-lactate averaged 96.6 and 164.4 mmol/h, whereas that of D-lactate averaged 10.5 and 71.8 mmol/h for C and G, respectively. Mean net portal volatile fatty acid absorptions were 442.8, 192.1, 53.8, 5.3 and 10.4 mmol/h (C) and 100.0, 47.2, 9.4, .98 and .78 mmol/h (G) for acetate, propionate, butyrate, isobutyrate and isovalerate, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual dimorphisms of the brain

Abstract: This discussion reviews, partially from the historical perspective of the author, the development and evolution of the concept of the sexual differentiation of the brain, a process that has profound implications for reproductive biology, animal behavior and developmental neurobiology. Although there are numerous sex differences in brain function, the mammalian brain appears to be fundamentally female. Characteristics of brain function typical of the male sex are imposed on the developing brain by the action of testicular hormones. In fact, estradiol produced intraneuronally by the aromatization of testicular testosterone, appears to be the hormonal molecule responsible for the masculine differentiation of the brain. Much of the research in this area has been descriptive in nature, and studies of the possible mechanisms of hormone action have been limited to very general approaches because of the complexities of the process and the lack of specific model systems. Recently, marked structural correlates of sexual differentiation have been identified. The sexually dimorphic nucleus of the preoptic area (SDN-POA), for example, is now viewed as a morphological signature of the action of gonadal hormones on the developing brain and has become a model system to investigate the fundamental mechanism(s) by which hormones act to determine the structure and functional capacity of the brain. Although possible effects of estradiol on neurogenesis and(or) neuronal migration cannot be excluded, it currently appears that one mechanism of the sexual differentiation of the brain is the hormonal promotion of neuronal survival during a developmental phase of neuronal death. The discovery of the SDN-POA in the rat emphasizes the value of the comparative approach to sexual differentiation. It is likely that other animal species may prove to be species of choice for future investigations of components of the complex process of the sexual differentiation of the brain.

Response of starter pigs to supplementation of corn-soybean meal diets with organic acids.

Abstract: Four growth experiments were conducted to assess the effects of organic acid supplementation on performance of starter and finisher pigs Three 4-wk starter experiments utilized 392 pigs fed simple corn-soybean meal diets A fourth experiment employed 135 finisher pigs in a 6-wk study Each of the starter experiments was initiated immediately after weaning; piglets were 30 +/- 3 d of age In Exp 1, weanling pigs fed a 19% crude protein, simple corn-soybean meal diet were compared with pigs fed similar diets supplemented with 2% propionic, fumaric, or citric acid Addition of each acid improved (P less than 07) efficiency of gain, while propionate depressed (P less than 05) feed intake Additions of 1, 2, 3 or 4% fumarate were made in Exp 2, resulting in linear daily gain and feed efficiency improvements (P less than 05) In Exp 3, a possible protein-sparing effect of fumaric acid was investigated Increasing protein levels from 16 to 20% improved daily gain (P less than 01) and feed efficiency (P less than 0001); fumarate supplementation (2%) increased (P less than 01) gain:feed However, there was no protein X fumaric acid interaction In Exp 4, no treatment effects were noted with performance of finisher pigs fed a 14% crude protein, corn-soybean meal diet was compared with that of pigs fed similar diets supplemented with 15 or 3% fumaric acid

Relationships among dietary lipid intake, serum cholesterol and ovarian function in Holstein heifers.

Abstract: Experiments were performed to determine whether serum concentrations of total cholesterol (TC) undergo cyclic changes during the estrous cycle of dairy heifers and to assess the relationship between serum concentrations of TC and ovarian steroid hormones. The effects of a hypercholesterolemic diet upon luteal progesterone secretion also were determined. Experiment 1 involved five dairy heifers exhibiting normal estrous cycles. Serum concentrations of TC, progesterone, testosterone and estradiol-17 beta were determined in blood samples collected throughout a complete estrous cycle. A transient decline in TC was observed during the luteal phase of all heifers beginning on d 2 and reached a nadir 6 d after estrus. Highest mean concentrations of TC occurred between d -2 and +2 (96.3 +/- 8.2 mg/dl), which were markedly higher (P less than .05) than the lowest mean concentrations (76.3 +/- 10.3 mg/dl) observed on d 6. Concentrations of serum TC were negatively correlated (r = -.40; P less than .01) with progesterone between d 2 and 9. Serum TC was not correlated with testosterone or estradiol-17 beta. In Exp. 2, seven cycling Holstein heifers were fed a control diet for 70 d (Stage I), a diet containing 15% whole sunflower seed as a source of supplemental dietary lipid for 70 d (Stage II) and then the control diet for 70 d (Stage III). Diets were isocaloric and isonitrogenous. All heifers were synchronized with prostaglandin F2 alpha after wk 5 in each of the three feeding stages.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic and environmental aspects of the growth curve parameters in beef cows.

Abstract: Brody's growth curve, a three-parameter function, and Richards' function, a four-parameter function, were fit to data from 233 inbred and linecross cows to study the genetic and environmental aspects of the growth curve parameters and to compare the two functions. Fitting Brody's curve was faster and less costly to compute than Richards' function, but Richards' function had smaller sums of squares and a better fit to actual data points. Year of birth had an effect on the A (P less than .05), b (P less than .01) and k (P less than .01) parameters of Brody's curve. Parameter estimates from data of the youngest cows were at the extremes. The b parameter was the largest when estimated from data with no recorded birth weights. Year of birth was also an important effect for the b (P less than .01), k (P less than .05) and m (P less than .01) parameters of Richards' function, but year effects were less interpretable. Mating system affected (P less than .01) the A parameter of both functions; inbreds were lighter than linecrosses at maturity. Line of sire was an important source of variation (P less than .01) for the A parameter of both functions. The heritability estimate of the A parameter from both functions was .44 +/- .27; apparently the same trait in both curves. The estimate for the b parameter from Brody's curve was .39 +/- .27, comparable with literature estimates of birth weight. The heritability estimate for k from Brody's curve was .20 +/- .26. The heritability estimates for b, k and m parameters from Richards' function were .24 +/- .26, .32 +/- .27 and .21 +/- .26, respectively. The genetic correlations between the A and k parameters in both curves indicated that cows with lighter mature weights reached that weight at younger ages.

Energy intake, body composition and reproductive performance of the gilt.

Abstract: The relationship between age, live weight, body composition and energy status on the onset and maintenance of reproductive activity in females is reviewed. When possible, swine studies have been employed, although, of necessity, much data are drawn from other species. The relationship between age, weight and puberty is controversial. However, from the available data we conclude that neither age nor weight are reliable indices of reproductive development, but that minimum threshold values for these characteristics must be achieved before puberty can occur. Human data provides a strong indication that a minimum adipose to lean tissue ratio is a prerequisite for puberty onset. Limited data from swine support this contention and indeed it may be a superior measure of reproductive development than either age or weight. However, the value of this ratio remains to be defined in pigs, and again it is minimum threshold level, the attainment of which is necessary, but not in itself sufficient, for puberty onset. A positive energy balance seems to be necessary for puberty onset and the maintenance of estrous cycles in some species, but this has not been investigated in swine. The mechanisms whereby adiposity and energy status influences reproduction are discussed. Human studies demonstrate a negative correlation between energy status, body fatness and plasma gonadotrophin levels. Also, adipose tissue has the ability to metabolize sex steroids, aromatizing androgens to estrogens and changing the direction of estrogen metabolism to produce more or less biologically potent estrogens.

Pituitary concentrations of gonadotropins and receptors for GnRH in suckled beef cows at various intervals after calving.

Abstract: Mature beef cows were slaughtered at 5 (n = 6), 10 (n = 6), 20 (n = 6) or 30 (n = 5) d after calving to identify endocrine events that may affect the duration of postpartum anestrus. Additional cows (n = 6) were slaughtered 12 to 14 d after their first postpartum estrus (luteal phase cows). Anterior pituitary concentrations of luteinizing hormone (LH) were low at d 5 (383 +/- 69 micrograms/g), averaged 445 +/- 103 and 682 +/- 207 micrograms/g at d 10 and 20, respectively, and were elevated (P less than .05) by d 30 (1,097 +/- 174 micrograms) to a concentration similar to luteal phase cows (1,208 +/- 148 micrograms/g). Concentrations of follicle-stimulating hormone (FSH) averaged 12.4 +/- 1.1, 9.6 +/- 2, 8.6 +/- 1.8 and 7.4 +/- 3.3 mg/g at d 5, 10, 20 and 30, respectively. Affinity (1.6 +/- .2 X 10(9) M-1) of anterior pituitary receptors for the GnRH (gonadotropin-releasing hormone) analog (DAla6; des-Gly10, [D-Ala6]-LH-RH ethylamide) and weights (2.1 +/- .1 g) of the anterior pituitaries did not differ among groups (P greater than .05). Number of receptors for GnRH averaged 37 +/- 7, 39 +/- 9, 25 +/- 5 and 23 +/- 5 X 10(-14) M/mg protein at d 5, 10, 20 and 30, respectively. Anterior pituitaries from luteal phase cows contained 22 +/- 2 X 10(-14) M/mg protein of receptors for GnRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Feed additive studies with newly weaned pigs: efficacy of supplemental copper, antibiotics and organic acids.

Abstract: Six experiments involving 706 newly weaned 28- to 32-d-old pigs were conducted to evaluate the efficacy of copper (Cu) sulfate (to provide 250 mg/kg Cu), antibiotic-sulfa combinations [chlortetracycline, 110 mg/kg + penicillin, 55 mg/kg + sulfamethazine, 110 mg/kg; i.e., Aureo-Sulfa-Penicillin (ASP) or tylosin, 110 mg/kg + sulfamethazine, 110 mg/kg; i.e., Tylosin-Sulfa (TS)] and anhydrous citric or fumaric acid (.75 to 1.5% of the diet). The basal experimental diet was a 19% crude protein (CP)-fortified corn-soybean meal diet (1.08% lysine) containing 7% dried whey and 3% fish meal. Marked and consistent gain and gain/feed responses occurred from the Cu supplement, particularly during the first week postweaning. The antibiotic-sulfa combinations were less efficacious than Cu during the 1-wk postweaning stress period. During either the 1- or 3-wk growth periods, ASP and TS showed additivity with Cu in promoting rate and efficiency of weight gain. Liver Cu was increased by Cu addition to the diet, but neither ASP nor TS affected Cu deposition in the liver. In a factorial experiment involving 17% (1.01% lysine) or 20% CP (1.23% lysine) corn-soybean meal diets containing either no dried whey or an addition of 25% whey, Cu supplementation elicited marked improvements in rate and efficiency of weight gain, particularly in diets without added whey. Likewise, whey addition improved pig performance, especially when added to the diets containing no supplemental Cu.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of selection for milk yield on endogenous hormones and metabolites in holstein heifers and cows

Abstract: Plasma concentrations of prolactin (PRL), growth hormone (GH), insulin, glucagon, glucose, urea and free fatty acids (FFA) were measured in Holstein calves, yearlings, bred heifers and primiparous cows, either sired by bulls with high predicted differences (PD) for milk (selection group) or by bulls from an unselected random bred control population (control group; n = 6). Serial blood samples were collected before and after feeding for an 8-h period from 0900 to 1700 h. All animals were fed a complete feed at 1100 h and administered insulin (.6 IU/100 kg body weight) at 1400 h. Mean plasma PRL was greater in control animals after feeding and insulin administration, while GH was greater overall in selection cattle. Insulin remained elevated longer in selection animals after exogenous administration, and plasma glucagon was increased in the control group. While plasma glucose and urea were unaffected by genetic group, plasma FFA were elevated in selection group calves and primiparous cows compared with the control group. All hormones and metabolites differed among the pre- and post-feeding and insulin administration periods and also with age. Mean PRL and GH increased after feeding, while glucagon decreased after exogenous insulin. Plasma FFA declined after feeding, while urea and glucose were similar before and after feeding. Mean PRL increased and glucagon decreased with advancing age and plasma GH and insulin showed inverse relationships at different ages. Plasma FFA changes closely followed GH changes with age, while plasma glucose more closely followed insulin changes with age. Results indicate that all hormones measured and FFA responded to genetic selection for milk, and increases in GH are uniformly associated with increased genetic potential for milk yield.

Comparison of four methods of calf confinement. I. Physiology.

Abstract: Holstein bull calves were blocked by birth order and randomly assigned to one of three treatments in trial I: stall (N = 7), pen (N = 7) and hutch (N = 7), and to one of four treatments in trial II: stall (N = 6), pen (N = 5), hutch (N = 6) and yard (N = 8). Stalls were elevated, .56 X 1.2 m, with wooden slatted floors. Stalled calves were tethered from the front with a collar and .5-m chain. Pens were elevated, 1.2 X 1.5 m, with wooden slatted floors and were located in the same open-front building as the stalls. Hutches were 1.2 X 1.2 X 2.4 m long and open on one end. Hutch calves were restrained with a dog collar and 2.4-m chain. Yard calves were housed as a group in a 3.6 X 7.9 m, outdoor enclosure, of which one-half was a covered, three-sided structure. Calves were placed on treatment between 12 to 24 h of age, bottle-fed 1.9 liters colostrum twice daily for 2 d and then bucket-fed 1.9 liters milk replacer twice daily, with continuous access to hay and grain. Jugular blood samples taken at 6 wk were analyzed for blood cell counts, blood chemistry profile (13 items), triiodothyronine (T3), thyroxine (T4), basal cortisol and adrenal response (cortisol) to exogenous adrenocorticotrophic hormone (ACTH). Average daily gain from 0 to 42 d was highly variable and was not significantly different for different treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution and retention of spermatozoa with acrosomal and nuclear abnormalities in the cow genital tract.

Abstract: Two experiments were conducted to evaluate the fate of sperm following uterine insemination. In Exp. I, five pairs of Holstein cows were inseminated with egg yolk-Tris extended semen (approximately 1.0 X 10(9) sperm; .5 ml) from five ejaculates from a single bull that had high levels (approximately 70%) of morphologically abnormal sperm. Cows were slaughtered 12 h after insemination. The genital tracts were removed and promptly clamped into defined regions. Sperm were recovered by flushing with 2.9% sodium citrate buffer. Proportions of abnormal sperm in the various regions were compared with those in the inseminate. Sperm numbers were also determined from each region. Regions of the tract varied in number of sperm (P less than .001), proportions of knobbed acrosomes (P less than .001), tapered heads (P less than .001), protoplasmic droplets (P less than .001), tail abnormalities (P less than .029) and total abnormalities (P less than .002). A total of 63.5 +/- 6.4 X 10(6) sperm was recovered. These sperm were distributed throughout the tract as follows: vagina, 91.8%; cervix, 5.4%; uterine horns, 2.7%, and uterotubal junctions-isthmi, .04%. No sperm were recovered from ampullae. Because retrograde movement of sperm from the uterus occurred in Exp. I, we conducted Exp. II to determine the extent of sperm loss from the genital tract following insemination. Three pairs of Holstein cows were inseminated with .42 X 10(9) sperm (.5 ml; egg yolk-Tris extender) from the same bull used in Exp. I (three ejaculates). All discharged mucus and urine was collected for 12 h after insemination for recovery of sperm. Aspirates (approximately 1 ml) of mucus from the vagina were evaluated during the 12-h post-insemination period for numbers of sperm and leucocytes. Sperm were also recovered from the tract following slaughter (approximately 12 h) to determine retention. Overall, 73 +/- 3.7% of inseminated sperm were recovered. Components were: inseminate lost from the genital tract in discharged mucus, 60 +/- 4.6%; lost in urine, .06 +/- .02%; aspirated from the vagina, 4.4 +/- 1%; adhered to equipment, 1.3 +/- .3%, and retained in the genital tract, 6.5 +/- 1.6%. Predicted numbers of sperm contained in discharged mucus 2 h post-insemination were greater (P less than .009) than at subsequent hours.(ABSTRACT TRUNCATED AT 400 WORDS)

Heterosis retained in advanced generations of crosses among Angus and Hereford cattle.

Abstract: Data from 1,909 purebred, F1, backcross and F2 and F3 inter se combinations of Angus and Hereford were used to estimate average individual, maternal and grandmaternal genetic effects, individual and maternal heterosis, dominance and epistatic genetic effects. Models for evaluating heterosis and epistatic or recombination effects were discussed. Average individual effects indicate that Angus, compared with Hereford, had calves that were born earlier, had lighter birth weights, lower pre- and postweaning gains and lower pregnancy rates. Angus also produced lighter weight carcasses with more fat cover and marbling. Maternal effects of Angus were in the direction of reduced birth weight, greater calving ease, higher preweaning but lower postweaning growth rate and increased fatness when contrasted with Hereford. There was a tendency for opposite direction of maternal and grandmaternal effects for traits influenced by preweaning maternal environment. When additive X additive effects were ignored, total heterosis was significant for earlier day born, heavier birth weight, preweaning and postweaning gain, and heavier and fatter carcasses. Heterosis retained in F3 inter se vs F1 generation crosses indicated that net epistatic effects were relatively negligible for date of calving, birth weight, weaning gain and fat cover. There was a greater reduction of heterosis effects than expected from dominance alone for survival, pregnancy and marbling score. Loss of heterosis in F3 was less than expected for postweaning gain, carcass weight and rib eye area. Except for survival, pregnancy and marbling, these deviations from dominance expectations, or lack of them, are favorable for F3 composite populations.

Comparison of four methods of calf confinement. II. Behavior.

Abstract: Holstein bull calves (N = 46) were blocked by birth order and randomly assigned to be individually reared in stalls, pens or hutches (trials I and II) or as a group in a 36 X 79 m yard (trial II only) Treatments differed by the degree of restraint and social isolation imposed, with stalls the most restrictive and yard the least Stalls and pens had wooden slatted floors; hutches and yard were on ground Calves were placed on treatment within 24 h of birth and remained on treatment 65 wk Total time standing or lying per 24 h in situ at 5 wk was not affected by treatment (P greater than 05), but hutch calves changed position between standing and lying more often than others (P less than 05), in order to remain in sun or shade At 65 wk, calves (N = 24) in trial II were individually open-field tested for 20 min in the presence of alien calves Stall and pen calves performed more actions utilized in locomotion and defense and engaged in more social behavior than hutch or yard calves (P less than 05) Only stall and pen calves stumbled and fell, but observations were insufficient to allow statistical analysis of these incidents Treatment effects were found with respect to vocalizations: stall and pen calves emitted more "baaocks," while yard calves emitted more "moos" Results of this study and of a companion physiological study of the calves suggest that the intensification of drives induced by chronic suppression of their release may be accompanied by physiological responses associated with chronic stress

Plasma prolactin, LH, FSH and estrogen excretion patterns in gilts during sexual development.

Abstract: Plasma prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in groups of eight gilts sampled every 20 min for 6 h at about 2-wk intervals between 15 and 192 d of age. The PRL levels were high at 15 and 28 d, declined at 40 d just after weaning and then rose slowly until 192 d of age. The number of LH pulses during 6 h was higher between 83 and 125 d than at the other periods. Magnitude of LH pulses was highest at 15 d, constant from 54 to 125 d, fell at 137 d and remained low until 192 d. Plasma FSH was high from 15 to 125 d, with a maximum at 54 d. It declined slowly until 168 d and did not change thereafter. Estrogen excretion was estimated from urine excretion of estrone (E1; conjugated plus nonconjugated E1) per 24 h from 40 d until puberty in three gilts and at 156 and 174 d in two other animals. The E1 excretion increased with age and four levels were described before peak values with the onset of first estrus. The first increase in E1 excretion occurred between 68 and 110 d, when antral follicles appeared in the ovaries. It was subsequent to the highest levels of FSH and concomitant with the increased frequency of LH pulses. The drop in levels of both gonadotropins after 125 d probably corresponded to the development of the negative feedback as a result of greater ovarian activity in these gilts.