The first case of genetically confirmed monozygotic twinning in the dog

Monozygotic twinning has not previously been genetically confirmed in the dog. This case report describes the finding of two viable male monozygotic foetuses within one placental site during caesarean section. Their umbilical cords attached to a single placenta. Genetic profiling using a total of 38 microsatellite markers, as well as amelogenin and SRY for sex determination, revealed identical DNA profiles, whether derived from blood or tissue (buccal swabs) samples. To the best of our knowledge, this is the first report of monozygotic twinning in the dog confirmed using DNA profiling.     

Embryo transfer and twinning in cattle

Recent developments in cattle embryo transfer are discussed, particularly those that are relevant to the commercial application of the technique. Cattle twinning for beef production could offer impressive economic advantages where nutrition is not a limiting factor and intensive management is possible. Evidence is discussed which suggests that cattle twins induced by embryo transfer may hold several advantages over naturally-occurring twins.

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Kurzfassung Neuere Entwicklungen auf dem Gebiet des Embryotransfer beim Rind werden diskutiert. Besonderer Wert wird dabei auf Techniken gelegt, die sich für eine kommerzielle Anwendung eignen. Zwillingsgeburten beim Rind für die Fleischproduktion bietet beeindruckende ökonomische Vorteile in Beständen, wo Ernährung kein limitierender Faktor und intensives Management möglich ist. Es werden Daten diskutiert, die darauf hinweisen, daß Zwillings-kälber von Embryotransferstudien eine Reihe von Vorteilen gegenüber natürlich geborenen Zwillingen aufweisen.

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Resume Les dévelopments récents en matière de transplantation embryonnaire chez les bovins sont discutés en particulier ceux ayant une appliavantages économiques là où la nutrition n'est pas un facteur limitant et l'élevage intensif possible. Il est clairement montré que les jumeaux obtenus par transplantation ovulaire offrent plus d'intérêt que les jumeaux spontanés.

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Riassunto Vengono discussi i recenti sviluppi delle tecniche di transferimento degli embrioni nel bovino, soprattutto di quelli che sono importanti ai fini dell'applicazione commerciale. La produzione di gemelli per una più alta produzione carnea potrebbe offrire rilevanti vantaggi economici dove l'alimentazione non rappresenta un fattore limitante e dove è possible l'allevamento intensivo. Vengono anche discusse le prove secondo cui i parti gemellari indotti nel bovino mediante transferimento embrionale potrebbero presentare molti vantaggi rispetto ai parti gemellari naturali.

     

Embryo-transfer twinning and performance efficiency in beef production

Effects of twinning on efficiency of beef production were estimated from results of bilateral transfer of two Angus x Hereford (AxH) embryos into each of 241 heifers and 84 cows (H, A, HxA or Holstein x H) over 4 yr. Calves were weaned at 180 d and fed either 220 d in a feedlot (1977) or 170 d on forage and 140 d in a feedlot (1978 to 1980). Effects of parity, twinning and sex of calf were estimated as covariates within year-breed of dam. Pregnancy at 45 to 60 d of gestation was 68% in heifers (H) and 74% in cows (C), with 40% single (S) and 60% twin (T) births. Dystocia was 28% in H vs 10% in C (P less than .05), and tended to be less (P greater than .05) for T than S in H. More placentas were retained (P less than .05) for T than for S in both H (35 vs 12%) and C (24 vs 4%). Twin gestations averaged 3 d shorter and subsequent calving intervals 13 d longer (P less than .05), but total calf mortality was slightly higher (P greater than .05). Abortions were 4% in H only. Twinning females lost maternal weight during late gestation (P less than .05) when crowding limited voluntary feed intake, while fetal requirements were 60% higher (P less than .01). Twins increased milk output 25% (P less than .05), but 11% higher feed intake maintained cow weight during lactation. Twinning reduced birth weight 13% and weaning weight 17% (P less than .05), but 400-d feedlot weight only 9% because of compensating feedlot gain. Twins gained 18% faster than S during postweaning 170-d forage feeding, but 5% slower in feedlot to 8% lighter 490-d weight (P less than .05). Assuming 40% higher veterinary and labor costs for twins, estimated integrated herd costs per unit of age-constant output value would be lower for T than for S production by about 24% for marketing either at weaning or at 400 d.     

犬的心理与实战应用

21世纪,犬已经远离了草丛树林和它们的猎物,而是走进钢筋水泥的城市中,搜索它新的猎物——爆炸危险品或毒品等走私物品,它们训练有素的鼻子可以轻易分辨出这些危害人类的气味。     

Association of a single nucleotide polymorphism in SPP1 with growth traits and twinning in a cattle population selected for twinning rate

Continued validation of genetic markers for economically important traits is crucial to establishing marker-assisted selection as a tool in the cattle industry. The objective of the current study was to evaluate the association of a SNP (T(9)/T(10)) in the osteopontin gene (SPP1) with growth rate in a large cattle population spanning multiple generations and representing alleles from 12 founding breeds. This population has been maintained at the US Meat Animal Research Center since 1981 and subjected to selection for twinning rate. Phenotypic records for this population included twinning rate and ovulation rate, providing an opportunity to examine the potential effects of SPP1 genotype on reproductive traits. A set of 2,701 animals was geno-typed for the T(9)/T(10) polymorphism at SPP1. The geno-typic data, including previously genotyped markers on chromosome 6 (BTA6), were used in conjunction with pedigree information to estimate genotypic probabilities for all 14,714 animals with phenotypic records. The genotypic probabilities for females were used to calculate independent variables for regressions of additive, dominance, and imprinting effects. Genotypic regressions were fit as fixed effects in a mixed model analysis, in which each trait was analyzed in a 2-trait model where single births were treated as a separate trait from twin births. The association of the SPP1 marker with birth weight (P < 0.006), weaning weight (P < 0.007), and yearling weight (P < 0.003) was consistent with the previously reported effects of SPP1 genotype on yearling weight. Our data supports the conclusion that the SNP successfully tracks functional alleles affecting growth in cattle. The previously undetected effect of the SNP on birth and weaning weight suggests this particular SPP1 marker may explain a portion of the phenotypic variance explained by QTL for birth and HCW on BTA6.     

正确的训练理念和犬且及从性训练的关系

犬是具有较复杂心理活动过程的动物,犬对主人真正意义上的服从应该是发自内心的服从,所以其服从性绝不可以认为单靠较强的机械刺激手段就能在一朝一夕中完成.如何培养犬的服从性,正确的训练理念直接影响着训练效果.     

Ovulation rate and twinning rate in cattle: heritabilities and genetic correlation

Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning project at the Roman L. Hruska U.S. Meat Animal Research Center. The animal model included numerator relationships among the animals and fixed effects of year-season of measurement, age at measurement, and birth group. Genetic correlations between averages of ovulation rates for three, four, five, six, seven, and eight estrous cycles and the occurrence of twins were, respectively, .62, .76, 1.00, 1.00, 1.00, and .98 based on observations on 200 to 325 puberal heifers. Corresponding phenotypic correlations ranged from .06 to .26. Genetic correlations between ovulation rate in a single estrous cycle and occurrence of twins were .38, .98, and .98, respectively, for 323, 430, and 283 cows with ovulation rate measured after measurement of twinning, in the same season as measurement of twinning, and more than 1 yr before measurement of twinning. Phenotypic correlations were .00, .07, and .00. Genetic and phenotypic correlations among ovulation rates at six consecutive estrous cycles averaged, respectively, .66 and .12 for 610 heifers. Heritabilities for ovulation rates in individual cycles averaged .16. No evidence of negative environmental covariance between ovulation rates in adjacent cycles was found. These results support the approach of indirectly selecting for twinning rate by measuring ovulation rates in estrous cycles of puberal heifers.     

Effects of twinning on gestation length, retained placenta, and dystocia

Constraints to maximal productivity from twinning in beef cattle include increased incidence of dystocia and retained placenta, longer postpartum interval, and lower conception rate. Incidence and cause(s) of the shorter gestation length and of the increased retained placenta and dystocia associated with twinning were evaluated for 3,370 single and 1,014 twin births produced in a population of cattle selected for natural twin births. Gestation length was shorter for twin than for single pregnancies (275.6 vs. 281.3 d, P<.01) and likely contributed to the higher incidence of retained placenta associated with twin births (27.9 vs. 1.9%; P<.01). Incidence of retained placenta was also higher in the spring (March-April) than in the fall (August-September) calving season (18.3 vs. 11.4%; P<.01). The higher incidence of dystocia with twins than with singles (46.9 vs. 20.6%, P<.01) was primarily due to abnormal presentation (37.0 vs. 4.5%, respectively) of one or both twin calves at parturition. First- (40.5%) and second- (22.7%) parity dams with a single birth had more (P<.01) dystocia than older dams (13.4%), whereas dystocia was not affected (P>.10) by parity with twin births. Because of the shorter gestation length and the increased incidence of retained placenta and(or) dystocia, achievement of increased productivity with twinning in cattle necessitates intensive management of twin-producing dams and their calves during the calving season. Management of the increased dystocia can be facilitated by preparturient diagnosis of twin pregnancies, enabling timely administration of obstetrical assistance to facilitate delivery of twin calves and to increase their neonatal survival.     

Effects of twinning on postpartum reproductive performance in cattle selected for twin births

The effects of twinning, dystocia, retained placenta, and body weight on postpartum reproduction were evaluated for 3,370 single and 1,014 twin births. Females were bred by AI for 40 d followed by 20 or 30 d of natural service with equal numbers bred and calved in spring and fall. Percentage of dams cyclic by the end of the AI period was lower (P<.05) for dams birthing and nursing a single calf (92.4%) than for dams birthing twins and nursing zero (98.7%) or two (94.7%) calves. Whereas the interval from parturition to first estrus was shorter (P<.01) for dams birthing and nursing a single (56.9 d) than for dams birthing twins and nursing one (68.5 d) or two (69.6 d) calves, length of the interval was further reduced by dystocia in nonlactating dams of either twins or singles (type of birth x dystocia, P<.05). Ensuing pregnancy rates were also affected by type of birth and dystocia. Without dystocia, dams birthing and nursing a single calf had a higher pregnancy rate (79.2%) than dams birthing twins and nursing one (61.7%) or two (66.3%) calves, whereas the lower ensuing pregnancy rates associated with dystocia in dams of singles (71.9%) resulted in similar rates among dams of singles and twins with dystocia (type of birth x dystocia; P<.01). Having a retained placenta resulted in a lower incidence of (93.5 vs. 96.4%, with vs. without; P<.05) and a longer interval to (64.7 vs. 59.2 d; P<.01) estrus while reducing subsequent pregnancy rates (X = 9.6%) in 3 of the 7 yr evaluated (retained placenta x year, P<.01). Because all parous females were bred during the same calendrical period, the shorter gestation length for twin calves (275.6 vs. 281.3 d) resulted in a longer interval from parturition to conception for twin births, whereas means for conception date differed by only 2 d between dams of twins and singles. Furthermore, a reduction (P<.01) in the interval to conception occurred with dystocia in dams of singles (89.3 vs. 85.0 d, without vs. with dystocia) and of twins nursed by zero (116.9 vs. 83.5 d), one (100.2 vs. 92.8 d), or two (96.1 vs. 97.2 d) calves. Another detriment to fertility was the higher incidence of fetal mortality or abortions associated with twin vs. single pregnancies (12.4 vs. 3.5%; P<.01). However, despite the lower conception rates for dams of twins, the increased prolificacy provides an opportunity to increase total beef production with a twinning technology.     

Induction of twinning in dairy or crossbred heifers by ipsilateral frozen embryo transfer

Induction of twinning by ipsilateral nonsurgical transfer of frozen two or demi-embryos was attempted in 129 virgin dairy or crossbred heifers that had been kept under a stable in our station (group-1), mountain field (group-2) and private farm (group-3) conditions. Ninety seven heifers (75%) were diagnosed pregnant by rectal palpation at 35 to 60 days of gestation; 86 heifers produced 37 sets of twins and 49 single calves. Pregnancy rate of group-1 was lower compared to those of groups-2 and -3 (63%, 88%, 78%, respectively). Abortion and mortality rates of group-3 were significantly lower (P less than 0.05) than those of groups-1 and -2 (8% and 6%, 12% and 16%, 18% and 24%). Twin calves had a lower birth weight (P less than 0.05) than singles. But there was no significant difference in weight between singles and twin calves at 270-330 days of age. Dystocia and difficult delivery were not observed in females producing twins. The incidence of retained placentas in twin calving cows (17%) was higher than that of single calving cows (2%). The interval to conceive postpartum was longer in twin calving cows (95 +/- 41 days) than in single calving cows (87 +/- 26 days). Gestation length was 5.0 days shorter for twin calving cows (P less than 0.05).     

Evaluation of numbers of microscopic and macroscopic follicles in cattle selected for twinning

We hypothesized that the number of microscopic follicles present in the ovaries of cattle selected for twin births (Twinner) would be greater than in the ovaries of contemporary Controls. Ovaries were collected from seven Control and seven Twinner cows at slaughter. The number of Small (1 to 3.9 mm), Medium (4 to 7.9), and Large (> 8 mm) surface follicles was counted and one ovary was fixed for histological evaluation. Fifty to sixty consecutive 6-microm slices were taken from a piece of cortical tissue, approximately 1 cm x 1 cm in area, located between the surface follicles. Microscopic follicles were classified as primordial (oocyte surrounded by a single layer of squamous pregranulosa cells), primary (oocyte surrounded by a single layer of one or more cuboidal granulosa cells), secondary (oocyte surrounded by two or more layers of granulosa cells), or tertiary (oocyte surrounded by multiple layers of granulosa cells with initiation of antrum formation to < or = 1 mm in diameter). The total number of follicles was counted in 200 fields (2 mm x 2 mm) per ovary. A field containing no follicles was classified as empty. There were significantly more secondary follicles in Twinner compared with Control ovaries (12.9 vs 6.3; P < .05). Twinners also tended to have more small surface follicles (35.4 vs 49.0; P < 0.1). We conclude that ovaries of Control and Twinner cows do not differ in the number of primordial follicles or in the number of follicles activated into the growing pool; however, Twinner cows are able to maintain more growing follicles at the secondary and subsequent stages of development.     

Canine conjoined twinning: A pathoanatomical study of a Lhasa Apso symmetrical cephalothoracopagus

A female pair of conjoined twins of the Lhasa Apso canine breed was subjected to tomographic and anatomical examinations. The twins had only one head and neck. The two ribcages were joined, extending to the umbilicus, with duplicated structures thereafter. They had three thoracic limbs and two pelvic girdles with four limbs, as well as a number of abnormalities in their internal organs. The data obtained were compared with the rare canine cases reported so far and with human cases.     

A case of conjoined cephalopagus twinning in an ostrich (Struthio camelus)

Conjoined twinnings have been reported in most domestic animal species and in some avian species. Cases of conjoined twins have not been reported in the ostrich so far. A hybrid Blue neck x African black male ostrich conjoined twinning was born at the end of artificial egg incubation and died spontaneously 24 h after the hatching. It was frozen and sent to the Unit of Veterinary Pathology of the University of Messina for gross examination. The most important gross findings involved the external body and most of the internal organs. On the basis of the duplication, the conjoined twins were classified as a cephalopagus. Radiological features included: development of one head containing a single brain, two spinal cords, deviated vertebral columnae with fusion of the two first cervical vertebrae. In one twin, the synsacrum was absent as well as portions of the vertebral column. Grossly, both twins showed two upper and lower limbs each. The gastro-enteric apparatuses of the twins were not completely developed and fused at different levels. One liver and one heart localized in the centre of the conjoined twins were observed. The authors conclude that the possible causes of the malformation could be related to a genetic factor.