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PubMed2006

Inbreeding trends and pedigree analysis of Irish dairy and beef cattle populations.

The objective of this study was to determine the inbreeding levels and to analyze the pedigree of Irish purebred populations of Charolais, Limousin, Hereford, Angus, and Simmental beef cattle, as well as the Holstein-Friesian dairy breed. Pedigree analyses included quantifying the depth of known pedigree, average generation intervals, effective population size, the effective number of founders, ancestors, and founder genomes, as well as identifying the most influential animals within the current population of each breed. The annual rate of increase in inbreeding over the past decade was 0.13% (P < 0.001) in the Hereford, 0.06% (P < 0.001) in the Simmental, and 0.10% (P < 0.001) in the Holstein-Friesian breeds. Inbreeding in the other breeds remained relatively constant over the past decade. Herefords had the greatest mean inbreeding in 2004, at 2.19%, whereas Charolais had the lowest, at 0.54%. Over half of each purebred population in 2004 was inbred to some degree; the population with the greatest proportion of animals inbred was the Hereford breed (85%). All 6 breeds displayed a generation interval of approximately 6 yr in recent years. In the pure-bred females born in 2004, the 3 most influential animals contributed between 11% (Limousin) and 24% (Hereford) of the genes. Effective population size was estimated for the Hereford, Simmental, and Holstein-Friesian only, and was 64, 127, and 75, respectively. The effective number of founders varied from 55 (Simmental) to 357 (Charolais), whereas the effective number of ancestors varied from 35 (Simmental and Hereford) to 82 (Limousin). Thus, despite the majority of animals being inbred, the inbreeding level across breeds is low but rising at a slow rate in the Hereford, Simmental, and Holstein-Friesian.

Animals↗
PubMed1985

Characterization of breeds of Bos indicus and Bos taurus cattle for maternal and individual traits.

Angus, Boran and Red Poll sires were mated to Ankole, Boran and small East African Zebu (Zebu) females to produce the cows characterized in this study, which produced calves by Friesian, Brown Swiss, Simmental, Boran and Red Poll sires. Individual traits included cow parturition weight, cow weight at weaning, cow mean weight and cow weight change from parturition to weaning; maternal traits included calf crop born percentage, preweaning viability percentage, overall viability percentage, birth weight, weaning weight, weight at 12, 18 and 24 mo and calf weight weaned per cow exposed to breeding (productivity index). Cows by Angus and Red Poll sires significantly exceeded cows by Boran sires (all cows in this comparison had Ankole and Zebu dams) in weaning weight of progeny and in cow weight at parturition and at weaning. Cows by Red Poll sires significantly exceeded cows by Boran sires in birth weight of progeny. Progeny of cows by Boran sires significantly exceeded progeny of cows by Angus and Red Poll sires in 24-mo weight. Cows by Angus and Red Poll sires did not differ (P greater than .05) in any of the traits analyzed. Cows with Ankole and Boran dams significantly exceeded cows with Zebu dams (all cows in this comparison had Angus and Red Poll sires) in progeny weight at birth, 18 mo and 24 mo and in cow weight at parturition and at weaning. Cows with Boran dams significantly exceeded cows with Zebu dams in weaning and 12-mo weight of progeny and significantly exceeded cows with Ankole dams in weaning weight of progeny. The significantly heavier weaning weight and significantly lighter 24-mo weight of the 3/4 Bos taurus progeny of cows with Angus and Red Poll sires relative to the 1/2 Bos taurus progeny of cows with Boran sires suggest that cattle that are 1/2 Bos taurus breed composition have greater general adaptation than cattle with 3/4 Bos taurus breed composition in the postweaning nutritive and climatic environment under which this experiment was conducted. Significantly heavier weights of Angus and Red Poll crossbred cows relative to Boran crossbred cows (all breeds crossed on Ankole and Zebu cows) indicate that the two Bos taurus breeds exceed the Boran (Bos indicus) breed in additive direct genetic effects for size when they have general adaptation to the environment.

Acclimatization↗
PubMed1982

Genetic, environmental and phenotypic relationships among gestation length, birth weight, growth traits and age at first calving in beef cattle.

Data on the Red Angus, Angus and Hereford herds of Pioneer Hi-Bred International, Inc., Des Moines, Iowa, collected from 1968 to 1976, were analyzed for relationships among gestation length, birth weight, prenatal gain (birth weight adjusted for gestation length), growth traits and age at first calving. A total of 5,691 calf records, 1,783 listing gestation length, were included in the study. Paternal half-sib analyses and least-squares procedures were used to compute heritability estimates and genetic, environmental and phenotypic correlations among traits. Genetic correlations among growth traits, including prenatal gain, were high in all cases. Heritability estimates for gestation length and birth weight were .36 and .43, respectively, for bull calves and .37 and .35 for heifer calves. Genetic correlations between these traits were .25 and .22 for bull and heifer calves, respectively. Gestation length was negatively correlated (genetically) with all growth traits except birth weight. This result suggests that faster growing fetuses may trigger parturition earlier than average. Age at first calving was negatively correlated (genetically) with growth traits, indicating a favorable relationship between growth and early reproduction. Analysis of several selection indexes combining either birth weight and yearling weight or gestation length and yearling weight indicated that continued response to selection for growth without excessive increase in birth weight is feasible. Selection for growth and moderate birth weight would be more effective than selection for growth and shorter gestation, suggesting that the former method would both shorten gestation and alter the growth curve. Repeatability estimates for gestation length and birth weight were .20 and .22, respectively. Maternal effects accounted for approximately 10% of the variation in each trait.

Analysis of Variance↗
PubMed2006

Growth- and breed-related changes of marbling characteristics in cattle.

The objective of this study was to investigate the growth- and breed-related changes of marbling characteristics in cattle. Four cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus, as a typical beef cattle; Galloway, as a smaller, environmentally resistant beef cattle; Holstein-Friesian, as a dairy-type cattle; and double-muscled Belgian Blue, as an extreme type for muscle growth, were used. These 4 breeds were expected to have differences in muscle development and i.m. fat deposition. Between 5 and 15 bulls of each breed were slaughtered at 2, 4, 6, 12, or 24 mo of age. Marbling characteristics were determined and classified in LM and semitendinosus muscle by computerized image analysis. Among breeds, differences appeared in the quantity, structure, and distribution of the marbling flecks in both muscles. The deposition of fat in the double-muscled Belgian Blue bulls remained substantially inferior to that of the other breeds, up to the age of 24 mo. Marbling in German Angus bulls particularly showed larger (P < 0.05) marbling fleck areas. Galloway cattle had the greatest (P < 0.05) number and the most regular (P < 0.05) distribution of the marbling flecks in young animals. Furthermore, for marbling characteristics in Holstein-Friesian animals, a great number and slightly finer structure were observed compared with the other breeds investigated. Postnatal growth-related changes of marbling in LM were characterized by as much as a 40-fold increase in the number of marbling flecks from 2 to 24 mo of age but also by up to a 4-fold enlargement in the area of the marbling flecks. The structure of marbling flecks was determined by 2 development trends. On the one hand, the marbling flecks became larger (P < 0.05), and the structure became coarser, which was reflected by an increasing (P < 0.01) proportion of long marbling flecks as well as an increasing (P < 0.01) maximum skeleton line length. On the other hand, continually new small, round marbling flecks appeared. This caused a decrease (P < 0.01) in the proportion of the 3 largest marbling fleck areas. The distribution of the marbling flecks became more regular (P < 0.05) with increasing proportion and number of marbling flecks. The results suggest that hyperplasia of adipocytes plays an important role in marbling during growth of muscle in cattle.

Adipose Tissue↗
PubMed1984

Grading and rotational crossbreeding of beef cattle. I. Reproductive performance.

Purebred Angus (A), Polled Hereford (PH) and Santa Gertrudis (SG) bulls were mated to grades, two-breed and three-breed rotational crosses of these breeds (seven herds) to produce three generations (G1, G2 and G3) of calves. The grade A and PH cows were higher in A and PH breeding, respectively, than grade SG cows were in SG breeding. Reproductive performance among grade and rotational-cross herds was evaluated for herd differences, heterosis and effects of various genetic components. For cows that produced G1 calves, the proportion of cows that calved, had a live calf and weaned a calf was higher (P less than .01) for those that calved compared with those that failed to calve the previous year. For cows that produced G2 and G3 calves, previous year's calving status did not affect (P greater than .05) reproductive performance. Grade A and PH were similar (P greater than .05) in reproductive performance during G1, G2 and G3. As generations advanced, SG decreased in reproductive performance. Except for the PH-SG rotational cross in G3, the A, PH and all two-breed rotational crosses and the three-breed rotational cross generally were similar (P greater than .05) for the three reproductive traits during each generation. Within generations, reproductive performance was similar (P greater than .05) between rotations within each of the two-breed rotational cross herds. For the three-breed rotational cross herd, differences due to rotation generally were not significant during G1 and G2, but for G3, the SG sires were associated with lower (P less than .05) reproductive performance for each of the three reproductive traits compared with A and PH sires. Heterosis percentages generally were positive but not significant for each of the three reproductive traits. On the basis of additive and maternal effects of A and SG expressed as deviations from PH, the only genetic component that significantly affected reproductive performance was the detrimental additive effect of SG in G2 and G3 for each of the three reproductive traits. Also, there was a consistent negative relationship between breed additive and maternal components for each of the three reproductive traits during each generation. Only 4 to 7% of the variation in reproductive performance was accounted for in the analyses that included breed additive, breed maternal, heterosis and average maternal heterosis effects. Averaged over generations, from .1 to .4% additional variation was due to factors that may have included specific maternal heterosis, epistasis and linkage.

Animals↗
PubMed2004

Effects of different grazing and feeding periods on performance and carcass traits of beef steers.

Over three consecutive years, 180 (60/yr) fall-born steer calves were weaned in May (average initial BW = 238 kg, SD = 36.2 kg) and allocated to one of three groups: 1) calf-fed steers that entered the feedlot at weaning; 2) short yearlings that grazed irrigated pasture for another 4 mo and entered the feedlot in September; and 3) long yearlings that grazed with short yearlings during the summer, remained on annual California foothills range through the fall, winter, and spring, and entered the feedlot the following May. All steers were fed until the average group backfat (BF), determined by ultrasound, reached 11 to 12 mm. On pasture, short- and long-yearling steers gained weight in the summer; long yearlings then slightly lost weight in the fall and winter, and then gained weight again the following spring. Average days in the feedlot were 188, 158, and 94 (P < 0.10) for calves, short yearlings, and long yearlings, respectively. Feedlot DMI increased with age (and weight) at feedlot entry, with no difference among groups in gain:feed ratio. The gain of BF was nil on pasture, even when animals were gaining weight, and then increased rapidly when animals were placed on a high-energy diet. Final body weights were heaviest (P < 0.10) in long yearlings, followed by short yearlings and then calves, indicating that a prolonged growing period increases the apparent mature size of the animal. Moreover, total carcass fat contents and percentage of Choice or above were all lower (P < 0.10) in cattle that were older at feedlot entry (i.e., long yearlings) compared with the other groups. In conclusion, increasing the backgrounding period decreased time and total concentrate requirements in the feedlot of Angus-Hereford steers. Older cattle reached 10 mm of BF at heavier weights. Grazing animals gained weight without increasing BF; however, BF increased rapidly in the feedlot. Prolonged grazing may decrease quality grade, either by impairing the ability of the animal to deposit intramuscular fat or by decreasing the time during which dietary energy supply is adequate for intramuscular fat deposition to occur.

Adipose Tissue↗
PubMed1993

Relationships between the thyroid and somatotropic axes in steers. II: Effects of thyroid status on plasma concentrations of insulin-like growth factor I (IGF-I) and the IGF-I response to growth hormone.

Three studies assessed the effect of thyroid status on regulation of plasma IGF-I in cattle. First, four Angus-Hereford steers (av wt 345 kg) were fed 4 mg/d propylthiouracil daily for 35 d. With continued feeding of PTU steers were sequentially injected with thyroxine (T4, 5 mg/d, IM for 5 d) followed by triiodothyronine (T3, 2 mg/d, IM for 5 d). An injection of bovine pituitary growth hormone (GH, 0.1 mg/kg, IM) was given to each steer on day 35 of PTU, day 5 of T4 and again on day 5 of T3. PTU alone increased plasma thyroid stimulating hormone (TSH), decreased plasma T4 and T3 but had no influence on IGF-I. T3, but not T4, lowered plasma TSH, IGF-I and the IGF-I response to GH (P < .05). Next, twelve bull calves (av wht 167 kg) were divided equally into two groups. A control group was injected daily for five d with buffered saline; the experimental group was concurrently treated with T3 (5 mg/d, sc) for five d. Beginning the sixth day, all calves were injected with GH (0.1 mg/kg, IM daily) for three d with the respective buffer or T3 treatments continuing. Plasma IGF-I was depressed 29% by T3. The incremental area under the three-d response curve was less (P < .03) in T3 cattle. A growth trial was conducted in which twenty-four Angus x Hereford steers were injected daily with T3 (2 mg/kg, bi-daily x 56 d) or implanted with Synovex-S (S) in a 2 x 2 factorial arrangement. Synovex increased empty body protein gain (EBPG) and plasma IGF-I 15.5 and 27.9% (P < .01), respectively; T3 decreased EBPG and plasma IGF-I 13.9 and 15.1% (P < .07), respectively, in steers which maintained suppression in plasma TSH. The data support the conclusion that elevated T3 decreases plasma IGF-I, in part, through a diminished GH-responsiveness and anabolic treatments such as S can reverse the effects of excess T3.

Animals↗
PubMed1989

Heterosis, maternal and direct effects in double-muscled and normal cattle: I. Reproduction and growth traits.

Data from a two-breed group diallel experiment involving double-muscled (DM) and normal (N) cattle were analyzed to evaluate the importance of heterosis, maternal and direct effects for reproduction and growth traits. The DM cattle were from a composite of primarily Angus, Charolais, Galloway and Hereford breeds, and N cattle were crossbred cattle with at least 50% Hereford breeding. The data comprised a total of 491 matings and 389 calvings in four breeding seasons. Records on calving performance, calving date, calf crop born and weaned, sex ratio of progeny and weight of calves were analyzed using least squares procedures. Significant heterosis of 5 to 12% was observed for all the calf crop and growth traits, except for birth weight. Heterosis resulted in 24% reduction in the incidence of dystocia and perinatal calf mortality (P less than .05). The significant heterosis was due mainly to poor production in DM X DM crosses. The DM cows were superior (P less than .05) to N cows in reciprocal crossing (maternal effect) for all the calf crop traits, but had higher incidence of calving difficulty and a higher proportion of male progeny. Significant direct effect was observed for all the traits except calving date and sex ratio among progeny. The N sires were superior for all the calf crop traits and caused less incidence of dystocia and perinatal mortality compared with the DM sires. Significant differences were obtained between the straightbreds for all the traits except calving date. The N straightbreds were superior to the DM straightbreds for all the significant traits.

Animal Feed↗
PubMed1995

Effect of breed, intake, and carcass composition on the status of several macro and trace minerals of adult beef cattle.

The objective was to determine the association between breed, intake, and carcass composition and the status of liver Cu, Zn, and Fe, and serum Cu, Zn, Ca, and Mg of 118 mature cows representing nine breeds of cattle. Breeds used were Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental. The cows were fed one of four levels of DMI: 58, 76, 93, and 111 g of DMI.wt-75.d-1. A ground alfalfa, corn, and corn silage diet was fed for up to 5 yr. There was no relationship between liver and serum concentrations of Cu, a negative correlation (P < .05) existed between liver and serum concentrations of Zn and a positive correlation (P < .01) existed between liver concentrations of Cu and Zn. Concentrations of serum Ca were positively correlated (Cu and Zn, P < .01; Mg, P < .05) with serum concentrations of Cu, Zn, and Mg, but negatively correlated (P < .01) with liver Fe. Liver Cu was higher (P < .05) for the Limousin breed than all others, except Angus. Liver Zn concentrations were higher (P < .05) for Limousin than for Pinzgauer, but no other breed differences were observed. Liver Cu concentration was not affected by daily intake, but liver Zn concentration increased (P < .05) with increased daily intake. Liver Fe concentration decreased (P < .01) in a curvilinear manner with increased daily intake. No breed differences in serum concentrations of Cu or Zn were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1976

The specificity and sensitivity of the fluorescent antibody test in cattle experimentally infected with Mycobacterium avium and Mycobacterium johnei.

In five calves experimentally infected with Mycobacterium avium and in 10 with M johnei it was shown that the serological response by the fluorescent antibody (FA) test was specific. The serological response in the M avium infected calves was transitory and lasted up to five months. The first evidence of a serological response with the FA test in the M johnei dosed calves occurred at four months, and all calves had reacted by nine months after dosing. At the 23 tests carried out between four and 32 months after dosing, when the experiment was terminated, an average of 5-8 animals was positive at any one test. Johne's disease was confirmed bacteriologically and histologically in six of the 10 calves though none had shown clinical signs.

Animals↗
PubMed1985

Mannosidosis in Galloway calves.

Mannosidosis was diagnosed in four stillborn Galloway calves and an autolyzed full-term fetus from experimental matings of carrier animals. Gross lesions were moderate internal hydrocephalus, and pallor and enlargement of the liver and kidneys and arthrogryposis. Histologic changes in the central nervous system of each calf were marked foamy vacuolation of the cytoplasm of neurones in the cerebral cortex, thalamus and brainstem, and vacuolation of the Purkinje cells of the cerebellum. Spheroids were common throughout the brain and there was also consistent severe foamy cytoplasmic vacuolation of renal tubular epithelial cells and hepatocytes. The activities of alpha-mannosidase, the lysosomal enzyme whose activity is deficient in mannosidosis, and activities of five other lysosomal enzymes were compared in brain, liver, and kidney tissues of three mannosidosis-affected calves and normal calf tissues. Tissues from the affected calves had a marked deficiency of alpha-mannosidase activity compared with the normal tissues; the greatest deficiency was in the liver (99%) and brain (98%). Activities of the other lysosomal enzymes were elevated in the affected tissues compared with normal. Mannosidosis is a lysosomal storage disease that results from a defect in glycoprotein metabolism and affects man, Angus and Angus-related breeds of cattle, such as Murray greys, and the cat. The congenital disease is caused by an inherited deficiency of the lysosomal enzyme alpha-mannosidase, and is inherited in an autosomal recessive manner. Mannosidosis was recently reported in a number of aborted and stillborn Australian Galloway calves from an experimental breeding trial. This is more detailed account of the histological and biochemical results obtained during the trial.

Animals↗
PubMed1992

Behavioral and tissue responses to severe phosphorus depletion in cattle.

Two-year-old Aberdeen Angus heifers were depleted of phosphorus (P) by loss of phosphate in saliva from a parotid gland fistula combined with a low-P diet. The inorganic phosphate concentrations (Pi) of plasma, parotid saliva, ruminal fluid, and feces were reduced, but cerebrospinal fluid Pi was unaltered. Plasma Pi fell to less than 1.0 mM in 12 wk, and the cows displayed an avid appetite for old bones. P-deficient cows preferred old weathered bones to fresh bones until the latter had aged for approximately 1.5 yr. They did not eat blood, peritoneal fat, or meat, fresh or aged for 2-3 yr. They did not eat Na or Ca phosphate salts or bone heated to greater than 250 degrees C. P-replete cows did not take or eat bones. The behavioral effects of P deficiency were associated with failure to gain body weight and maintain condition, significant bone changes indicated by reduced bone weight and specific gravity, osteopenia indicated by radiology, evidence of reduced bone formation indicated by plasma osteocalcin levels and histology, and abnormal estrous cycles. Prolonged P deficiency was associated with increased plasma concentrations of total Ca and 1,25-dihydroxyvitamin D and reduced plasma concentrations of parathyroid hormone.

Animals↗
PubMed1987

In vitro viral expression as a criterion for development of control procedures for enzootic bovine leukosis.

In a university beef herd of 304 cattle in which six died of lymphosarcoma between 1980 and 1984, 77% of the Angus and 26% of the Charolais cattle were determined to be infected with bovine leukemia virus (BLV). Changes in iatrogenic procedures were initiated as early control measures. In vitro viral expression (VE) was used as a criterion to identify cattle for subsequent segregation or culling. This involved determinations of percentages of BLV-associated lymphocyte profiles among thin-sectioned Ficoll-Paque-isolated blood lymphocytes that were processed into plastic after culture for 48 h. Cattle retained until completion of nutritional studies or as breeding stock were separated into two groups. The BLV-seronegative cattle, BLV-seropositive cattle with 0% VE, and BLV-seropositive cattle with 1% to 4% VE were placed in group 1. Seropositive cattle with greater than or equal to 5% VE were placed in group 2. In 1985, evaluation of in vitro VE in 108 mature BLV-seropositive cattle retained for breeding revealed 36 (33%) had no observable VE. In 1986, 58 of 108 cattle were available to be reexamined, and 21 (36%) had 0% VE in both years. The VE expression values for individual cattle were generally comparable over the 2-year period. Of 48 initial seronegative breeding stock housed in group 1 with BLV-seropositive cattle with low or no VE, 21 (44%) seroconverted during 1985 to 1986. A positive correlation of 0.585 was found between VE and age-related absolute lymphocyte number.

Animals↗
PubMed1980

Characterization of cattle of a five-breed diallel. III. Puberty in bulls and heifers.

Pubertal characters of bulls and heifers produced in a diallel mating of Angus, Brahman, Hereford, Holstein and Jersey cattle were analyzed. Ninety-one heifers and 138 bulls in individual pens adn 286 bulls in drylots were fed a 72% TDN diet ad libitum; another 384 heifers were placed on pasture with supplemental feed. Puberty in heifers was defined as time of first ovulatory estrus; in bulls, as first detection of sperm cells in an electroejaculate. Breed type least-squares means, adjusted for birth month, were estimated within sex-nutrition-management groups and then decomposed into breed effects, average heterosis (h), general combining ability (GCA) and specific combining ability (SCA) by diallel analysis techniques. Breed effects were a significant source of variation for all characters studied. Heterosis (h, GCA, SCA) was not significant for pubertal age of bulls or heifers receiving complete diets in pens, a rather high nutritional plane. However, on pasture, crossbred heifers reached puberty at a younger age (P less than .05) than straightbreds. Average heterosis was significant (P less than .05) for increased weight and hip height at puberty and ratios involving these characters for both sexes. Specific combining abilities were not statistically significant for the majority of the pubertal characters, yet large differences among estimates of combining abilities were expressed. Ad libitum feeding of the penned heifers tended to decrease pubertal age and increase pubertal size as compared to pubertal age and size of pastured heifers. The breed type x management interactions within both sexes indicated a different ranking of the breed types for each management regimen.

Animals↗
PubMed2004

Reassessment of the toxicity of Hypericum perforatum (St John's wort) for cattle.

OBJECTIVE: To investigate the clinical effect of administering sufficient Hypericum perforatum to cattle to deliver quadruple the reported oral toxic dose. ANIMALS: Thirty-six yearling Hereford (n = 18) and Angus (n = 18) steers. DESIGN: A series of six experiments was conducted, each using 12 animals in a 2 x 2 factorial design, with two breeds of cattle (Hereford, Angus) and two dose levels of hypericin, 1.5 mg/kg (treated group) and 0 mg/kg (control group). Each set of 12 steers was used in duplicate experiments, with all animals alternated between treated and control groups. PROCEDURES: Treated groups received finely milled H. perforatum administered orally in gelatin capsules to provide 1.5 mg hypericin/kg body weight. All cattle were then exposed to direct sunlight for 5 h per day for 5 successive days. Rectal temperatures were measured immediately before and at the end of each sunlight exposure session. Rectal temperature above 40 degrees C, together with some other clinical sign of hypericin poisoning, was considered indicative of intoxication. RESULTS: No animals developed a rectal temperature above 40 degrees C or other clinical signs of hypericin poisoning. CONCLUSIONS: While the reported bovine oral toxic dose of 3 g dried plant/kg body weight, for flowering stage, presumed narrow leaved biotype, H. perforatum, is probably correct, the corresponding dose for hypericin of 0.37 mg/kg is incorrect. Based on its known concentration in this plant the toxic dose of hypericin for partially pigmented Hereford-cross cattle is estimated at about 10.5 mg/kg body weight and more than this for fully pigmented cattle. This would imply that cattle of the former type should be about three and a half times better protected against H. perforatum toxicity than are unpigmented, wool protected, Merino sheep. Cattle, particularly if fully pigmented, may have a role in grazing management to control H. perforatum.

Administration, Oral↗
PubMed2006

Isolation and characterization of the bovine microsatellite loci.

Microsatellite loci were isolated using five repetitive probes for Korean native cattle. Eleven microsatellite loci were developed based on a biotin hybrid capture method, and enrichment of the genomic libraries (AAAT, TG, AG, T, and TGC repeats) was performed using Sau3AI adapters. The isolated markers were tested in two half-sib Korean cattle families and four imported breeds (Angus, Limousine, Holstein, and Shorthorn). Nine informative microsatellite loci were observed, and two microsatellite loci were revealed as monomorphic in Korean cattle. In the imported breeds, however, all of the markers were informative. In total, 213 alleles were obtained at the 11 loci across five breeds, and the average number of alleles found per locus, considering all populations, was 4.26. Heterozygosity was 0.71 (expected) and 0.57 (observed). The range of the polymorphic information content for the markers in all cattle populations was 0.43-0.69. Eleven percent of genetic variation was attributed to differentiation between populations as determined by the mean F (ST) values. The remaining 89% corresponded to differences among individuals. The isolated markers may be used to identify and classify the local breeds on a molecular basis.

Animals↗
PubMed2004

Site and extent of digestion and amino acid flow to the small intestine in beef cattle consuming limited amounts of forage.

Eight Angus x Gelbvieh heifers (445 +/- 74.5 kg) fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square double double-crossover designed experiment to assess the effect of restricted forage intake on site and extent of digestion and flow of essential AA amino acids to the small intestine. Heifers were fed chopped (2.54 cm) bromegrass hay (9.2% CP, 64% NDF on an OM basis) at one of four percentages of maintenance (30, 60, 90, and 120%). Experimental periods were 21 d in length, with 17 d of adaptation followed by 4 d of intensive sample collection, after which maintenance requirements and subsequent level of intake were adjusted for BW change. True ruminal OM, NDF, and N digestion (g/d) decreased linearly (P < 0.001) with decreasing forage intake. When expressed as a percentage of OM intake, true ruminal OM and N digestibility were not affected (P = 0.23 to 0.87), whereas ruminal NDF digestibility tended to increase (P = 0.09) as forage intake decreased. Total and microbial essential amino acid flow to the duodenum decreased linearly (P = 0.001) from 496.1 to 132.1 g/d and 329.1 to 96.0 g/d, as intake decreased from 120 to 30% of maintenance intake, respectively. Although the profile of individual essential amino acids in duodenal digesta (P = 0.001 to 0.07) and isolated ruminal microbes differed (P = 0.001 to 0.09) across treatment, the greatest difference noted for total and microbial essential amino acid profile was only 0.3 percentage units. Because total and microbial flow of essential amino acids to the small intestine decreased as OM intake decreased, but true ruminal degradability of individual essential amino acids (P = 0.17 to 0.99) and digesta essential amino acid profile were comparable across treatments, total essential amino acid supply to the small intestine was predicted using OM intake as the independent variable. The resulting simple linear regression equation was: total essential amino acid flow = (0.055 x OM intake) + 1.546 (r2 = 0.91). The model developed in this experiment accounted for more of the variation in the data set than the current beef cattle NRC model, which under-predicted total flow of essential amino acids to the duodenum. The prediction equation developed herein can be used to estimate the supply of essential amino acids reaching the small intestine when formulating supplements to compensate for potential amino acid deficiencies resulting from restricted forage intake.

Adaptation, Physiological↗