Influence of melatonin receptor 1A gene polymorphisms on seasonal reproduction in Sarda ewes with different body condition scores and ages.

In several species, circadian changes in melatonin concentrations play a key role in the photoperiodic control of seasonality. In sheep, two silent mutations in the melatonin receptor 1A gene (MTNR1A) at positions 606 and 612 of the exon II are associated with seasonal reproduction. However, in some sheep breeds, no relationships have been found between MTNR1A polymorphisms and reproductive seasonality. This lack of relationship could be due to effects of breed, body condition, age, and/or environmental conditions. Thus, the present study was conducted with the Sarda sheep breed with the aim of documenting the effect of MTNR1A gene polymorphisms on reproductive resumption and to evaluate whether such this effect was modified by differences in body condition score (BCS) and age. Six hundred three- to six-year-old multiparous ewes with BCSs between 2.5 and 3.5 were selected. Genomic DNA was extracted and subjected to PCR to amplify the ovine exon II of the MTNR1A gene. The amplicons were subjected to digestion with the restriction enzymes RsaI and MnlI to detect the T606C and A612G polymorphisms, respectively. Ewes carrying the G/G, G/A, C/C, and C/T genotypes exhibited higher fertility rates (P<0.05) and fewer numbers of days between the introduction of rams and parturition (P<0.05) than did the A/A and T/T genotypes. The data revealed that the MTNR1A gene polymorphisms influenced spring reproductive resumption in the Sarda sheep breed. Moreover, the data also indicated that, over the limited ranges evaluated in this study, BCS and age had no significant influence on reproductive activity.

Effect of genotype at the MTNR1A locus and melatonin treatment on first conception in Sarda ewe lambs.

A sample of 423 Sarda ewe lambs from three different farms was used to evaluate the effect of one or two melatonin implants on the time of first conception. On each farm, 141 animals were divided into three groups. On June 30 these animals received either no treatment (Group C), 18 mg melatonin (Group M1, one implant), or 18 + 18 mg melatonin (Group M2, two implants). Thirty-five days after treatment, rams were introduced in the ewe lambs flock and subsequently removed after 40 days. Lambing dates were recorded between 150 and 190 days from the first day of male introduction. Genotyping and sequencing of the MT1 exon 2 were carried out to analyze the structure and the possible influence of the MT1 receptor gene on reproductive response to melatonin treatment. Melatonin-treated animals had a higher rate of pregnancy (P < 0.05) and lambed earlier (P < 0.05) compared with untreated animals. Single nucleotide polymorphisms were found in exon II of MT1 gene at positions C606T and G612A leading to genotypes C/C, C/T or T/T and +/+, +/- and -/-, respectively. Melatonin-treated animals of +/+ genotype showed a higher number of pregnancies (P < 0.05) and lambed earlier (P < 0.05) compared to untreated animals of the same genotype. Melatonin treatment did not affect reproductive activity in any other genotype analyzed. No correlation between genotype and the time of first conception was found in untreated animals. Concluding data revealed the positive effect of melatonin treatment on the time of first conception in ewe lambs and highlighted that +/+ genotype is able to influence reproductive response to melatonin treatment.

Polymorphism of the melatonin receptor MT1 gene and its relationship with seasonal reproductive activity in the Sarda sheep breed.

The aim was to study the polymorphisms of the melatonin receptor 1A gene (MTNR1A) and its relationship with seasonal reproduction in the Sarda sheep breed. Four-thousand multiparous ewes reared under natural photoperiod were randomly chosen. Genomic DNA was extracted and subjected to PCR for the amplification of the main part of exon II of the ovine MTNR1A gene (GenBank U14109). PCR products were subjected to restriction enzymes MnlI and RsaI and placed into +/+, +/- or -/- group for MnlI and C/C, C/T or T/T group for RsaI. Samples were cloned and sequenced. The sequences were aligned with the U14109 sequence of GenBank. Data were subjected to allelic frequency analysis and to the chi(2) test in order to evaluate the link between genotype and reproductive activity. After MnlI digestion, allelic frequency was 0.78 for allele +and 0.22 for allele -; genotype frequency of the +/+ homozygote was 68%, 20.5% for +/- and 11.5% for -/-. After RsaI, allelic frequency was 0.66 for allele C and 0.34 for allele T; genotype frequency of the C/C homozygote was 53.5%, 26% for C/T and 20.5% for T/T. The population was in Hardy-Weinberg disequilibrium both for the MnlI and RsaI. Lambing frequency of +/+ genotype ewes was higher in the period September-December while for -/- genotype in January-April (P<0.01). Lambing of C/C genotype ewes showed a higher frequency in September-December while for T/T genotype in January-April (P<0.01). Results confirmed that the polymorphism of the MTNR1A locus was also present in the Sarda with a higher incidence of the +/+ and C/C genotypes. The animals that carried one of these two gene isoforms showed a not seasonal reproductive activity with the lambing period in September-December.

Relationship between MTNR1A melatonin receptor gene polymorphism and seasonal reproduction in different goat breeds.

The reproductive activity of goats bred in temperate latitude follows a seasonal pattern, influenced by annual variation in day length. Daily variation in pineal melatonin secretion is the neuroendocrine signal recognized by animals through the link between this hormone and melatonin receptor 1a (MTNR1A). A total of 345 goats of different breeds (225 Sarda, 30 Saanen, 30 Chamois Coloured, 30 Maltese and 30 Nubian) with a kidding period in October-December or January-March were analysed to verify if a link exists between the structure of the receptor gene and reproductive activity. The main part of exon II of MTNR1A gene was amplified by PCR and then digested with MnlI and RsaI to prove the presence of restriction sites. Sequencing of 20 cloned samples and 20 purified samples permitted comparison with previously published sequences. No polymorphism was found using MnlI enzyme, as all 345 samples showed the cleavage site in position 605 and all the goats were MM genotype. However, using RsaI enzyme, some Sarda goats, showed a polymorphic site in position 53. Nine Sarda goats were R/r genotype, lacking this cleavage site only in one allele, while the other animals, both Sarda and the other breeds, presented the cleavage site in both the alleles and were thus R/R genotype. No r/r genotype was found in any of the breeds. In Sarda goats the allelic frequency was 0.98 for R allele and 0.02 for r allele; genotypic frequency was 96.00% for R/R genotype and 4.00% for R/r genotype. A strong link emerged from statistical analysis (P<0.001) between R/r genotype and reproductive activity, which was strongly influenced by photoperiod. Sequencing indicated six nucleotide changes that did not induce any amino acid change. Data showed that polymorphism was present and that it influences reproductive activity only in the Sarda breed.

The effect of shearing procedures on blood levels of growth hormone, cortisol and other stress haematochemical parameters in Sarda sheep.

The aim of this research was to investigate how growth hormone (GH) cortisol and some haematochemical parameters could be modified by the stress caused by the stages of shearing in Sarda breed sheep. Five groups of 10 sheep each were formed. Group A, only separated from the flock; Group B, only tied; Group C, both tied and shorn (animals in these three groups were ewe lambs shorn for the first time); Group D, adult females both tied and shorn; and Group E, adult entire males both tied and shorn (animals in these two groups had been shorn previously). Five blood samples were taken from each animal: the day before treatment (first sample); at the start of the treatment (second sample); in the middle of shearing for Groups C, D and E, 10 min after separation in Group A and 10 min after tying in Group B (third sample); at the end of treatment (fourth sample); and on the day after treatment (fifth sample). Plasma GH levels showed a decrease (P < 0.01) in Groups A, B, C and D during treatment (third and fourth samples), while Group E only at the end of shearing (fourth sample). In the third sample, the highest GH levels were recorded for Group E (P < 0.05), while it was recorded in the fourth sample for Groups A and E (P < 0.05). Cortisol levels showed a clear increase (P < 0.01) in all groups during treatment, but Group A showed a decrease in the fourth sample in comparison to the third sample. Males in the second, third and fourth sample and Group A only in the fourth sample showed lower cortisol levels when compared with the other groups (P < 0.05). Plasma glucose levels showed an increase (P < 0.01) in all groups during treatment but Groups B, C and E showed the highest values (P < 0.05). Magnesium (Mg) showed an increase in all groups in the third and fourth sample, while sodium (Na), in the same samples, only in Groups B, C and D. Potassium (K) values showed a significant decrease (P < 0.05) only in Groups C and D at the end of shearing. These results show that GH secretion is influenced by all the stress procedure: separation, tying and shearing. Shearing, even if necessary for animals, causes a significant change of the blood parameters involved in the stress response.

[Effect of recombinant bovine somatotropin on the secretion and composition of milk in Sardinian ewes]. / Effetto della bST ricombinante sulla secrezione e sulla composizione del latte nella pecora sarda.

To verify the effect on the milk yield, 5 Sardinian ewes at 45 days from lambing were given two subcutaneous administrations, in a sustained-release vehicle, of recombinant bST in the dose of 3 mg/Kg of live weight, at 28 day intervals. Other 5 ewes of the same age, weight, distance from lambing and milk yield, were kept untreated. The observations lasted 56 days. The individual milk yield was recorded daily while both the milk (dry matter, ash, fat and protein) and some blood parameters (glucose, triglycerides, albumin, total protein, urea nitrogen, phospholipids, total and HDL cholesterol, calcium, phosphorus and magnesium) were checked weekly for each subject, by standard analytical methodology. The rbST significantly influenced the milk yield (+9.75% for the treated group) as already found in cows. The milk composition and the checked blood parameters were unaffected by the treatment.

[Hematologic parameters of the white donkeys of Asinara]. / Costanti ematiche dell'asinello bianco dell'Asinara.

In 14 albino donkeys (6 males and 8 females) aged 1-12 years, about 25% of the whole population, 30 blood parameters were determined, with automatic equipment, monthly, for 4 months. No significant differences between sexes or compared with other donkey breeds were found, in spite of the particular characteristics of the population and of their environment.

[Effect of the sudden removal of lambs on the blood levels of prolactin, triiodothyronine and thyroxine in ewes]. / Effetto dell'improvvisa sottrazione della prole sul livello ematico di prolattina, tri-iodotironina e tiroxina nella pecora.

The effect of the sudden removal of lambs, average age 42 days (36 to 54), on the blood level of PRL, T3 and T4 was checked, using a radioimmunological method, in 18 Sardinian ewes that had lambed in November (10 treated and 8 control). The two groups of animals, reared indoors in different sheep-folds, were subjected to the same management and feeding. Compared to day before the removal of the lambs, the blood PRL showed a sharp decrease which lasted 24 hours. After 4 days of observation, despite two daily milkings, the blood PRL had not returned to the initial levels. On the other hand, T3 and T4 showed an increase that lasted 48 hours, on the third day returning to the initial levels.

[The horses of Giara: variation of the thyroid activity and certain blood parameters between winter and summer]. / Il cavallino della Giara: variazioni dell'attività tiroidea e di alcune costanti ematiche tra l'inverno e l'estate.

The changes of some parameters in the blood serum of six Giara horses (3 males and 3 females) were checked weekly, in relation to the environmental temperature throughout a one winter and summer. T3, total lipids, triglycerides, urea nitrogen, creatinine, total protein, albumin, beta and gamma globulin showed significant difference between winter and summer and, with the exception of triglycerides, urea nitrogen and total protein were correlated to the environmental temperature. T4, glucose, uric acid and alpha globulin showed no difference between the two seasons and no correlation with the temperature. The results indicate that the seasonal variations in thyroid activity affected the T3 only, and that the blood lipids were transported from the beta globulin and, perhaps, in a smaller quantity, from the albumin, while the alpha globulin was not affected.

[Hematologic and hematochemical characteristics of the herring gull (Larus argentatus) and the buzzard (Buteo buteo)]. / Caratteristiche ematologiche ed ematochimiche del gabbiano reale (Larus argentatus) e della poiana comune (Buteo Buteo).

Some hematological and hematochemical parameters in eight herring gulls (Larus argentatus) and in six buzzards (Buteo buteo) were checked. The buzzards were fed with ovine meat exclusively, while the herring gulls were fed with fish and ovine meat. Considerable differences between the two species were noted, particularly as far as the hematological and lipidic parameters are concerned. These differences are probably related to the aquatic life of the herring gull.

[Seasonal changes in blood testosterone in the Giara horse]. / Andamento stagionale del testosterone ematico nel cavallino della Giara.

The blood testosterone changes in three Giara stallions, average age 8 years old and average weight 183 Kgs, were checked weekly for a year using a radioimmunological method. The horses showed a highly seasonal hormonal activity concentrated in the first half of the year (winter and spring). In the second half of the year (summer and fall) the stallions showed low levels of testosterone. The highest level of the androgen hormone occurred in April, the lowest in October. The absolute levels of this hormone agreed substantially with the relative literature.

[Hematochemical parameters in calves before, during and after weaning to a regular diet]. / Parmetri ematochimici in vitelli prima, durante e dopa lo svezzamento al pascolo.

The Authors studied the changes of 17 blood parameters of calves before, during and after a traditional weaning. Concentrations of total protein, albumin, urea nitrogen, creatinine, glucose, cholesterol, triglycerides, alkaline phosphatase, total bilirubin and phosphorus were determined by an automated assay system; sodium, potassium and chloride by a flame photometer; calcium, magnesium, copper and zinc by an atomic absorption spectrophotometer. Observed changes can be referred to: 1) the change of the digestion (glucose); 2) the age of the subjects (alkaline phosphatase); 3) the increase of weight (creatinine); 4) the type of feeding (phosphorus, copper and zinc). Sodium, potassium, chloride, calcium and magnesium did not change during the weaning.