The purpose was to analyze the growth hormone GH1/GH2-N and GH2-Z gene copies and to assess their possible association with milk traits in Sarda sheep. Two hundred multiparous lactating ewes were monitored. The two gene copies were amplified separately and each was used as template for a nested PCR, to investigate single strand conformation polymorphism (SSCP) of the 5'UTR, exon-1, exon-5 and 3'UTR DNA regions. SSCP analysis revealed marked differences in the number of polymorphic patterns between the two genes. Sequencing revealed five nucleotide changes at the GH1/GH2-N gene. Five nucleotide changes occurred at the GH2-Z gene: one was located in exon-5 (c.556G > A) and resulted in a putative amino acid substitution G186S. All the nucleotide changes were copy-specific, except c.*30delT, which was common to both GH1/GH2-N and GH2-Z. Variability in the promoter regions of each gene might have consequences on the expression level, due to the involvement in potential transcription factor binding sites. Both gene copies influenced milk yield. A correlation with milk protein and casein content was also evidenced. These results may have implications that make them useful for future breeding strategies in dairy sheep breeding.

No abstract

The effect of CSN1S1 genotype and lactation stage on milk yield and composition were investigated in 80 extensively reared goats. Milk yield was recorded in early, mid and late lactation and individual milk samples were collected to determine: fat, protein, lactose and casein content, pH, freezing point, somatic cell count (SCC) and total microbic mesophilic count (TMC). Relative casein composition and amino acid profile were quantified by HPLC. Fatty acid profile was measured by gas-chromatography. Genotype did not affect milk yield, while this trait was significantly affected by lactation stage (P < 0.01). CSN1S1 BB goats produced significantly higher protein and casein percentages (P < 0.05). αs1-casein (CN) was significantly higher in BB and AB goats than AF and BF, showing intermediate values in AA goats (P < 0.01). The protein percentage and the αs1 and αs2-CN fractions were not affected by lactation stage, while the casein content and the β and κ-CN significantly increased throughout lactation (P < 0.01). C4 : 0 and C6 : 0 were not affected by genotype, while C8 : 0 and C10 : 0 were higher in the AA goats than BB; most of the long chain FA were higher in BB than AA goats. MUFA and PUFA increased in late lactation. In addition, BB goats showed higher essential amino acids, resulting in an optimal composition from the nutritional point of view, when compared with AA goats. The increase of MUFA, PUFA, essential and cis-FA in late lactation indicate that the lipid composition of goat's milk, with the progress of lactation, tends to improve its nutritional value.

This study evaluated the effect of storage on renneting properties of goat milk investigated using the Formagraph method. Milk samples from 169 goats in three farms (F1, F2 and F3) were analysed during an entire lactation (45, 75, 105, 135 and 165 days in milking DIM), to obtain renneting parameters, both from fresh milk and after storage with Bronopol and freezing at -20°C and -80°C. As regards fresh milk, mean values of clotting time were between 12·51 (45 DIM) and 13·29 min (105 DIM and F2), the curd firming time between 1·77 (45 DIM) and 2·15 min (F1) and curd firmness between 42·09 (165 DIM) and 49·55 mm (45 DIM). No statistical difference was recorded after storage. After regression analysis, all prediction models showed significance value at P<0·001 with the highest R2 value for clotting time, 0·710 (fresh vs. frozen milk at -20°C), and the lowest for clot firmness, 0·281 (fresh vs. frozen milk at -80°C). Results demonstrated that assessment of goat milk coagulation properties using the Formagraph method is also achievable after freezing or Bronopol addition.

-The aim of this study was to compare the allele frequency of �'-UTR NRAMP1 (Natural Resistance-Associated Macrophage Protein) microsatellite between local and specialized dairy cattle breeds reared in Sardinia, Italy. Blood samples were collected and DNA was e�tracted from ��7 Sarda, �� Italian Brown and ��� Italian Friesian cattle and analysed by means of PCR and PCR-SSCP. On the whole, three alleles were found, GT 1� , GT 14 , and GT 1� . GT 1� showed the highest frequency in all the breeds�� 0.874 in the Sarda, 0.��7� in the Italian Brown and 1 in the Italian Friesian. For the Sarda, both GT 14 and GT 1� showed a frequency of 0.0���, while for the Italian Brown 0.018 and 0.00��, respectively. Homozygous GT 1� /GT 1� was the unique genotype for the Italian Friesian and the most representative for the Italian Brown (0.����4) and Sarda (0.82�). The other genotypes for the Sarda were�� GT 14 /GT 14 (0.042), GT 1� /GT 14 (0.010), GT 1� /GT 1� (0.0��4) and GT 14 /GT 1� (0.0�1); as regards the Italian Brown, both GT 14 /GT 14 and GT 1� /GT 1� showed a genotypic frequency of 0.018. The observed heterozygosity was lower than the e�pected value both for the Sarda and the Italian Brown. Sarda showed a higher genetic variability than Italian Brown and Italian Friesian.