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Biomedical subjects

R D Shanks

Publications and source records attributed to R D Shanks.

At least 37 records · Page 2Linked to original sources
PubMed1994

Association of deficiency of uridine monophosphate synthase with production and reproduction.

Interaction between genotype at locus for uridine monophosphate synthase and parity was reexamined for 305-d mature equivalent milk and fat production and calving interval. Three lactations for cows of known genotype defined two data files corresponding to different sampling procedures. The first data file selected by herd contained records on 23 cows that were deficient in activity of uridine monophosphate synthase and on 1081 cows with normal activity; the second data file contained records on 19 cows with deficient activity and on 17 cows with normal activity, all daughters of bulls known to be heterozygous at the locus for uridine monophosphate synthase. Results from the mutually exclusive data files were determined independently and then pooled. Genotype and parity interaction, tested against mean square error, was not supported for any of the three traits. Mean differences of the two genotypes, averaged across data files, were, for first, second, and third parities, respectively, 360, 568, and 299 kg for milk; 6, 9, and 8 kg for fat; and 22, 9, and 12 d for calving interval. Main effect of genotype indicated a 417-kg advantage for heterozygotes but 17-d longer calving interval. The main effect of genotype on milk production adjusted for calving interval was 343 kg but was nonsignificant.

Animals↗
PubMed1993

Milk and fat yields decline in bovine leukemia virus-infected Holstein cattle with persistent lymphocytosis.

Effects of bovine leukemia virus (BLV) infection on milk and fat yields were studied by using data collected from Holstein cows over a 6-year period. Milk and fat yields in BLV-infected cows with persistent lymphocytosis (PL) declined significantly relative to their BLV-infected non-PL herdmates. Declines were most pronounced in cows older than 6 years. The estimated loss to the dairy industry due to PL is more than $42 million annually. A major histocompatibility complex class I (BoLA-A) allele that has been previously associated with resistance to PL was associated with longevity and realization of milk production potentials, indicating that genetic resistance to PL will have an economic benefit in herds where BLV is endemic.

Age Factors↗
PubMed1993

Low incidence of citrullinemia carriers among dairy cattle of the United States.

Bovine citrullinemia is an autosomal recessive disorder that is lethal in the early postnatal period. Dairy bulls from the US were screened for citrullinemia genotype with a mutation-specific assay of semen or leukocyte DNA. One heterozygote was detected among 367 US Holstein bulls tested, corresponding to an incidence of .3%; DNA sequencing showed that this bull (bull C) was heterozygous for the translation-termination mutation described as the cause of bovine citrullinemia. Tests on daughters of bull C revealed that 26 were heterozygous and 25 were homozygous normal, confirming that the condition is autosomal recessive and that bull C was heterozygous. Although bull C was among 273 bulls tested from the top 400 bulls based on Type-Production Index as of July 1990, he was not among the 90 tested from the top 100. He has fewer than 2000 offspring registered with the Holstein Association of America and has few sons in AI. Furthermore, he was culled for other reasons before his citrullinemia status was known. Accordingly, the incidence of citrullinemia carriers is low among US Holsteins, and the impact of the one carrier found on the future of the breed is expected to be minor. No carriers were found among 102 US Guernsey bulls and 53 US Jersey bulls tested.

Animals↗
PubMed1993

Lactation potential as a criterion for strategy of feeding total mixed rations to dairy cows.

A trial was conducted from freshening to 30 wk postpartum to evaluate assignment of cows into production potential groups based on early lactation performance to optimize the time for switching from high to medium nutrient concentration TMR. Cows received a TMR formulated for early lactation until wk 4 of lactation and a high nutrient concentration TMR until 13, 19, or 25; the high TMR was followed by a medium nutrient concentration TMR until the end of the trial. Cows were assigned to high, medium, or low potential groups separately for parities 1, 2, and > or = 3 based on daily 3.5% FCM production as a percentage of BW measured during wk 6 and 7 of lactation. Low potential cows tended to partition energy intake into BW gain earlier in lactation than medium and high potential cows. For low potential cows, an early transfer to medium TMR moderated BW gain with no negative effect on production. High potential cows maintained their BW on the high ration; however, early transfer negatively affected production. Classification of individual cows into potential groups based on early lactation performance can serve as a useful tool for TMR feeding strategy later in lactation.

Animal Feed↗
PubMed1992

Identification of the homozygous recessive genotype for the deficiency of uridine monophosphate synthase in 35-day bovine embryos.

Holstein-Friesian cattle heterozygous for the deficiency of uridine monophosphate (UMP) synthase have half-normal activity of UMP synthase. The homozygous recessive genotype would result in little or no activity, has not been observed among live animals and apparently leads to embryonic mortality at approximately Day 40 of gestation. Activity of UMP synthase averaged 2.74 +/- 0.61 units/mg protein for 19 obligatory normal embryos (from normal x normal matings). Activity for 18 embryos from heterozygote x heterozygote matings yielded three non-overlapping groups as follows: (i) five presumed normals with greater than two-thirds normal activity, (ii) ten apparent heterozygotes with one-third to two-thirds normal activity and (iii) three putative homozygous recessive embryos with less than one-third normal activity. The distribution among these groups was consistent with the 1:2:1 ratio expected for autosomal inheritance. Conception of embryos homozygous recessive for this disorder was demonstrated.

Animals↗
PubMed1992

Atresia coli inherited in Holstein cattle.

A mating plan was designed to test the genetic hypothesis that atresia coli is inherited as an autosomal recessive at a single locus with two alleles. Matings between 8 putative carrier sires and 56 putative carrier dams resulted in 59 normal and 8 atresia coli calves, which was not different from the expected number of 8.1 affected calves. One case of atresia coli was observed among 628 calves born concurrently in the herd. All of the affected calves born from planned and contemporary matings were inbred, and their dominance relationships with each other were greater than zero, which is complementary evidence of pairs of alleles in common among affected calves. In planned matings, 7 of the 39 pregnancies diagnosed during the first 40 d of gestation of putative carriers produced affected calves. In contemporary matings, for pregnancies diagnosed before d 41 of gestation, there were 1 affected and 295 normal calves. Atresia coli in Holstein calves was associated with putative carrier parents. Retrospective analysis of early pregnancy diagnosis in dams was inconclusive in evaluating the role of palpation on atresia coli in genetically predisposed calves.

Animals↗
PubMed1992

Incidence of atresia coli and relationships among the affected calves born in one herd of Holstein cattle.

Eighteen cases of atresia coli were observed in the University of Illinois Holstein herd from 1974 through August 1983 in 2367 births. The overall incidence of the abnormality was .76% during this period. All of the affected calves were related to one another, and 15 of them were inbred. More calves were born with atresia coli from dams in which pregnancy was diagnosed prior to d 41 of gestation than from dams in which pregnancy was diagnosed later. Early pregnancy diagnosis in dams may contribute, but was not essential, to atresia coli in Holstein calves. Thirteen of the affected calves were males. The proportion of calves aborted or born dead among the affected calves was greater than expected from the incidence of aborted or born dead among contemporary calves.

Animals↗
PubMed1992

Comparative responses of lactating cows to total mixed rations or computerized individual concentrates feeding.

A trial was conducted in a commercial dairy herd in which the concentrate part of the ration was fed individually to a group of cows through computerized self-feeders. Performance results were compared with those of a group fed TMR of 65 to 67% concentrates. Rationing of individual concentrates was according to parity, milk yield, milk yield potential, BW changes, and bunk feed-stuffs. Mean intake of concentrates per cow was about 1 kg/d lower in the individually supplemented cows. This was partly compensated for by a higher intake of bunk feedstuffs. Overall daily milk yield per cow was similar to those receiving a TMR in first parity cows, higher in second parity cows, and lower in third and greater parity cows. The higher performance of the second parity cows was achieved in all milk yield potential classes, and the lower yield in subsequent lactations was due to lower performance in low and high potential classes. The individually supplemented cows gained less BW than those in the TMR group. Milk yield per unit of BW was better than milk yield as a variable to refine individual cow supplementation strategy for allocation of concentrates. Results also suggest that the same criteria used for supplementation of concentrates can be beneficial to cows' assignments and movements among different TMR groups. Computerized dispensing of concentrates, when applied properly, can economize on consumption of concentrates when grouping and feeding different TMR are impossible.

Animal Feed↗
PubMed1992

Relationship between genetic merit of Holstein bulls and deficiency of uridine-5'-monophosphate synthase.

Heterozygotes for a deficiency of uridine-5'-monophosphate synthase, a metabolic disease that interferes with pyrimidine biosynthesis, were related to a common ancestor, Skokie Sensation Ned. Predicted Differences of milk, fat, dollars, and protein from the July 1986 sire evaluation on 290 Holstein bulls born between 1975 and 1981 were analyzed for differences in the following groups: 5 heterozygous sons, 7 heterozygous grandsons, 5 normal sons, 20 normal grandsons of Ned, and a random sample of 253 normal bulls unrelated to Ned. From generalized least squares analysis, heterozygotes had higher estimates of genetic merit by 158 kg PD milk, 37 PD dollars, and 4.9 kg PD protein. Although an advantage was observed for heterozygotes within a family, descendants of Ned had lower estimates of genetic merit than their normal contemporaries. Sons of Ned had higher PD protein than grandsons of Ned, regardless of their uridine-5'-monophosphate synthase level. Propagation of the reproductively undesirable allele for deficiency of uridine-5'-monophosphate synthase should be controlled.

Animals↗
PubMed1992

Timing of insemination in dairy heifers.

Data representing 676 AI of 372 virgin dairy heifers during 1984 to 1987 at the University of Illinois were analyzed by analysis of variance to determine the effect of timing of AI on conception rate. Standing to be mounted, bawling, and attempting to mount were the three criteria used for determining the presence of estrus. More than 90% of the observations were conducted by one herdsperson between 0700 and 1600 h daily. Heifers were artificially inseminated with frozen semen from 58 bulls by one of two technicians. Conception rate on first AI was 56%, determined by return to estrus or 33- to 50-d rectal palpation for pregnancy. Conception rate to second and later AI was near 40%. Eighty-six percent of the heifers conceived during the trial. The average interval between first observation of standing estrus and AI was 10.5 h; the range was 15 min to 33 h. The model discussed contained six variables: time interval between first observation of standing estrus and AI (group), breed, sire within breed, year bred, season bred, and inseminator. The analysis of variance of conception to first AI showed timing of AI and service sire as the two most significant effects. Conception to first AI was worst when AI occurred 13.5 to 33 h after first observation of estrus. No factors considered were significant sources of variation for second or later AI.

Animals↗
PubMed1991

Effects on chick performance of ammonia and heat stressors in various combination sequences.

The purpose of the present study was to evaluate the effects of previous experience with a stressor on chicks' subsequent performance when exposed later to the same stressor or to a different stressor. Performance was measured in chicks exposed to aerial ammonia, environmental heat, or both in reciprocal sequences in two consecutive periods. Four (2 x 2 factorial) treatment combinations of ammonia [0 ppm (a) or 125 ppm (A)] and heat [30 C (h) or 36.5 C (H]) stressors were imposed in each of two consecutive 4-day periods, giving a total of 16 treatments. Weight gain (G), feed intake (F), and the gain:feed ratio (G:F) in Periods 1 (Days 9 to 13 posthatch) and 2 (Days 13 to 17 posthatch) were analyzed. Stressors decreased performance in both periods, but the effect was greater in Period 2. Synergism between A and H in Period 2 decreased chicks' G, F, and G:F in Period 2. Stress-depressed productive traits in Period 1 were succeeded in Period 2 not by residual negative effects but by compensatory responses: prior exposure to stressors in Period 1 was not detrimental to the chicks' subsequent G or G:F in Period 2. For example, chicks switched from Treatment ah in Period 1 to AH in Period 2 had lower G in Period 2 than did those going from either Ah, aH, or AH in Period 1 to AH in period 2. It was concluded that exposure to stressors early on enhanced the chicks' ability to cope with the same or with different stressors later and that compensatory responses occurred as the result of short-term exposure to stressors.

Ammonia↗
PubMed1990

Reproductive consequences of deficiency of uridine monophosphate synthase in Holstein cattle.

Cattle heterozygous for deficiency of uridine monophosphate synthase required more breeding services per calving when mated to other heterozygotes than did matings of normal cattle. Gestation length, number of breeding services per calving, and days from breeding to pregnancy examination were monitored on 759 complete gestations, 76 false-positive pregnancy diagnoses, 14 false-negative pregnancy diagnoses, and 413 negative pregnancy diagnoses in a dairy herd between 1983 and 1987. For complete gestations, 15 heterozygote x heterozygote matings required 3.13 +/- 0.37 breeding services per calving, which was significantly more than the 2.05 +/- 0.05 breeding services required for normal x normal matings; gestation length and days from breeding to pregnancy examination were similar between mating types. For false-positive pregnancy diagnoses, females diagnosed pregnant, but subsequently found not to be pregnant, 5 heterozygote x heterozygote matings averaged 51 +/- 23 days of gestation, which was less than the 93 +/- 6 days required for 71 normal matings; services and days from breeding to pregnancy examination were similar between mating types. All false-negative pregnancy diagnoses, females diagnosed not pregnant but later found to be pregnant, were made on cattle with normal matings. For negative pregnancy diagnoses, heterozygous matings averaged 0.3 more breeding services per examination than normal matings.

Animals↗
PubMed1989

Milk and fat production in dairy cattle influenced by advanced subclinical bovine leukemia virus infection.

Genetic potentials (pedigree-estimated breeding value) for milk and for fat were compared in cows grouped according to subclinical stage of bovine leukemia virus infection. Genetic potential for milk production was significantly greater in seropositive cows with persistent lymphocytosis (622 +/- 72 kg) and in seropositive hematologically normal cows (554 +/- 34 34 kg) than in seronegative herdmates (418 +/- 53 kg). When 305-day twice-daily-milking mature equivalent milk production records for the current lactation were adjusted for genetic potential, bovine leukemia virus-infected cows that were hematologically normal had significantly greater milk production than did seronegative herdmates, suggesting that early bovine leukemia virus infection was positively associated with milk yield. Genetic potential for fat production was significantly greater for cows with persistent lymphocytosis (21 +/- 2 kg) than for other seropositive (16 +/- 1 kg) and seronegative herdmates (13 +/- 2 kg); however, 305-day twice-daily-milking mature equivalent fat production for the current lactation was not significantly different between the groups. Thus, cows with persistent lymphocytosis did not produce fat according to their genetic potential. As an apparent consequence of tendencies for greater milk yield and less fat production, milk fat percentage was significantly reduced in cows with persistent lymphocytosis (3.33 +/- 0.09%) and other seropositive cows (3.48 +/- 0.05%) relative to seronegative herdmates (3.67 +/- 0.07%). These results suggest a need to reevaluate the economic impact of bovine leukemia virus infection on the dairy industry.

Animals↗
PubMed1989

Monoclonal antibodies specific for rat relaxin. IV. Passive immunization with monoclonal antibodies during the antepartum period reduces cervical growth and extensibility, disrupts birth, and reduces pup survival in intact rats.

The purpose of this investigation was to use an approach targeted specifically on endogenous relaxin to determine the influence of antepartum (days 20-22) relaxin on cervical modifications and birth in the rat. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to neutralize endogenous relaxin in intact pregnant rats. MCA1 or PBS vehicle was administered iv to intact rats daily from days 20-22 of pregnancy. Cervices were removed at 1200 h on day 22. Cervices obtained from MCA1-treated rats were less extensible than cervices obtained from PBS-treated control rats. Furthermore, wet weight, dry weight, water content, and uronate content were lower in cervices obtained from MCA1-treated rats than in cervices from PBS-treated controls. Birth and maternal behavior of MCA1-treated and PBS-treated control rats were observed continuously from 2100 h on day 22 until day 2 postpartum (d2PP). MCA1-treated rats exhibited significantly prolonged durations of litter delivery as well as reduced incidences of live pups on d2PP compared with controls. There were lower incidences of normal maternal behavior observed at birth and on d1PP with MCA1-treated rats than with control rats. In addition, little or no milk was observed in the abdomen of most live pups of MCA1-treated rats on d2PP, whereas abundant milk was observed in the abdomen of all live pups of control rats. The mean live pup weight on d2PP was lower in the litters of MCA1-treated rats than in control litters. The present study indicates that in the rat endogenous relaxin is needed during the antepartum period for normal cervical growth and extensibility, normal litter delivery, and high postpartum pup survival. This work supports the hypothesis that the influence of endogenous relaxin on birth is attributable, at least in part, to its effects on the cervix.

Animals↗
PubMed1989

Hormonal control of the cervix in pregnant gilts. I. Changes in the physical properties of the cervix correlate temporally with elevated serum levels of estrogen and relaxin.

The time course of changes in the physical properties of both the uterine and vaginal portions of the cervix were studied during the last two thirds (days 40 to approximately 115) of pregnancy in the gilt. To obtain insight concerning the hormonal control of these physical changes, serum levels of relaxin, estrone, 17 beta-estradiol, and progesterone were also determined. Throughout midpregnancy, the extensibility (softness), lumen diameter, and wet weight of the uterine portion of the cervix were less than those of the vaginal portion of the cervix. After day 80, marked and sustained increases in these three physical parameters occurred in the uterine portion of the cervix whereas slight (extensibility) or moderate (lumen diameter and wet weight) increases occurred in the vaginal portion of the cervix. By day 110, extensibility, lumen diameter, and wet weight of the uterine portion of the cervix were similar to those of the vaginal portion of the cervix. Because the uterine portion of the cervix has a relatively firm consistency and small lumen throughout most of pregnancy, we conclude that it probably plays a more important role than the vaginal portion of the cervix in protecting the uterus and its contents during pregnancy. The marked changes in the physical properties of the uterine portion of the cervix are temporally correlated with elevated serum estrogen levels (days 80-100) or estrogen and relaxin levels (day 100 to term). We conclude that estrogen or, more likely, estrogen and relaxin in combination may promote the modifications in the physical properties of the cervix that occur during the last 35 days of gestation.

Animals↗