D. Zygoyiannis

The effects of polymorphisms in the DGAT1, leptin and growth hormone receptor gene loci on body energy, blood metabolic and reproductive traits of Holstein cows.

The objective of this study was to examine the impact of polymorphisms in the acyl-CoA:diacylglycerol acyltransferase (DGAT1), leptin and growth hormone receptor genes on body energy (body condition score, total body energy content and cumulative effective energy balance) and blood metabolic traits (levels of beta-hydroxybutyrate, glucose and non-esterified fatty acids), measured once before the first calving and then repeatedly throughout first lactation in 497 Holstein cows. The influence of the same polymorphisms on cow reproductive performance and health during the first and second lactations was also assessed. Several reproductive traits were considered including interval, conception and insemination traits, as well as incidence of metritis and reproductive problems. Genotyping was performed using PCR-RFLP (DGAT1, leptin) or allele-specific PCR (growth hormone receptor). For each locus, the effect of allele substitution on body energy and blood metabolic traits was estimated using random regression models. The same effect on reproductive traits was assessed with single-trait mixed linear models. Significant (P<0.05) effects on specific reproductive traits were observed. DGAT1 and growth hormone receptor alleles responsible for significant increases in milk production were found to have an adverse effect on reproduction, while the leptin allele responsible for significant increase in milk production was linked to marginally increased metritis frequency. Furthermore, the three studied loci were also found to significantly (P<0.05) affect certain body energy and blood metabolic traits. Several associations are published for the first time, but these should be confirmed by other investigators before the polymorphisms are used in gene-assisted selection.

Eating quality of lamb meat: effects of breed, sex, degree of maturity and nutritional management

The eating quality of lamb meat of three indigenous Greek dairy breeds of sheep, reared under different nutritional management conditions, was assessed by Taste Panel Tests (TPT). Lean samples from the leg joints of 69 lamb carcasses of the Boutsko (B), Serres (S) and Karagouniko (K) breed were used. For the first TPT, 24 lambs (four males and four females of each breed) were reared in individual pens on a concentrate ration fed ad libitum. For the second TPT, 27 individual penned male lambs were fed on Lucerne hay ad libitum and on three different levels of concentrate: High (H), Medium, (M) and Low (L). For the third TPT, 18 male lambs were used; initially the groups were fed indoors for 63 days on three different levels of concentrate (H, M and L) together with ad libitum Lucerne hay, and subsequently finished on irrigated, sown pasture. For TPT 1, leg joints were obtained from lambs that had been slaughtered at 30, 45, 60 or 90% of mature weight (PMW) for each breed. For TPT 2, lambs were slaughtered at 23, 28 or 33 kg target slaughter live weights (TSLW), common for all breeds. For TPT 3, lambs were slaughtered at 48 or 55% of PMW for each breed. Panellists assessed warm, roasted lean samples of leg joints and rated Flavour, Juiciness, Tenderness and Overall Acceptability. In TPT 1, degree of maturity significantly affected Flavour, Tenderness and Overall Acceptability whereas sex affected only Flavour. In TPT 2, breed and concentrate level significantly affected the quality characteristics, but concentrate level had no significant effect in TPT 3. Effects associated with slaughter weight were significant for most characteristics in all TPT, with decreasing acceptability for older/heavier lambs. Significant interactions were found between breed and the other factors in TPT 2 and TPT 3 for most quality characteristics. Results from these studies suggest changing traditional production systems may enhance the eating quality of lamb meat.

Fatty acid composition of carcass fat of indigenous (Capra prisca) suckled Greek kids and milk of their does

Abstract Fatty acids in decreasing contents in subcutaneous and perinephric carcass fat were oleic, palmitic, stearic, myristic, linoleic, palmitoleic, lauric, linolenic and capric acid. Odd-numbered acids and branched chain acids were approximately mid-way. There was no evidence of difference between sexes, except for the fat depots. Subcutaneous fat of younger kids (5 weeks old) had a significantly lower proportion of linolenic, palmitoleic and other (odd-numbered and branched chain) acids (P Milk fatty acids in decreasing contents in total fat were oleic, palmitic, stearic, myristic, capric, linoleic, lauric, caprylic, caproic, butyric, palmitoleic, myristoleic and linolenic acid. Myristoleic, stearic, linoleic and palmitic acids increased with stage of lactation (P It is concluded that carcass fat of kids and milk fat of their does is rich in saturated fatty acids. Because of this, carcass fat of suckled kids is harder than that of suckled lambs.

The epizootiology of gastrointestinal nematode parasites in Greek dairy breeds of sheep and goats

Gastrointestinal (GI) parasitism represents a severe health problem in small ruminant production systems world-wide. The objective of the present study was three-fold: (i) to assess the prevalence of GI parasitism in dairy breeds of sheep and goats in selected areas of Greece; (ii) to determine the species of existing gastrointestinal parasites; and (iii) to investigate the effect of climatic factors on the seasonal variation of parasite population dynamics in dairy sheep and goats reared in two different geographical areas of Greece. The study was conducted in four flocks of either sheep or goats that were equally allocated in northern and central Greece. In each flock, faecal samples were randomly collected from 30 animals at monthly intervals and were used for nematode egg counts and coprocultures. Two animals from each flock were slaughtered monthly and their GI tract were examined for adult worm population and identification. The study revealed that the parasitic burdens in sheep were significantly (P<0.05) higher than those in goats. Faecal egg counts for both sheep and goats were significantly (P<0.01) affected by the month of the year and there was also a significant interaction between month of the year and area of study (P<0.01). Teladorsagia, Haemonchus, Trichostrongylus and Chabertia were the most prevalent nematode genera in both sheep and goats. Such information could be useful for the development of strategic treatments when sheep and goats are reared under systems similar to those described in this study.

Genetic Relationship of Body Energy and Blood Metabolites with Reproduction in Holstein Cows

Body condition score (BCS), energy content (EC), cumulative effective energy balance (CEEB), and blood serum concentrations of glucose, beta-hydroxybutyrate (BHBA), and nonesterified fatty acids (NEFA) were measured throughout first lactation in 497 Holstein cows raised on a large commercial farm in northern Greece. All these traits are considered to be indicators of a cows energy balance. An additional measure of BCS, EC, and blood serum glucose, BHBA, and NEFA concentrations were taken approximately 2 mo (61 +/- 23 d) before first calving. During first lactation, first service conception rate, conception rate in the first 305 d of lactation, interval from calving to conception, number of inseminations per conception, incidence of metritis, and incidence of reproductive problems of these cows were recorded; interval between first and second calving, and second lactation first service conception rate were also recorded. Random regression models were used to calculate weekly animal breeding values for first lactation BCS, EC, CEEB, glucose, BHBA, and NEFA. Single trait animal models were used to calculate breeding values for these traits measured on pregnant heifers before calving. Reproductive records were then regressed on animal breeding values for these energy balance-related traits to derive estimates of their genetic correlations. Several significant estimates were obtained. In general, traits that are known to be positively correlated with energy balance (BCS, EC, CEEB, and glucose) were found to have a favorable genetic relationship with reproduction, meaning that increased levels of the former will lead to an enhancement of the latter. On the other hand, traits known to be negatively correlated with energy balance (BHBA and NEFA) were found to have an unfavorable genetic association with reproductive traits. Body condition score, BHBA, and NEFA recorded early in lactation, and glucose concentrations measured in pregnant heifers had the highest genetic correlation with future reproductive performance. Results suggest that genetic selection for body energy and blood metabolites could facilitate the genetic improvement of fertility and overall reproductive efficiency of dairy cows.

Fatty acid composition of lambs of indigenous dairy Greek breeds of sheep as affected by post-weaning nutritional management and weight at slaughter

The objective was to assess the effect of breed, sex, post-weaning nutrition and weight at slaughter on the fatty acids (FA) composition in carcass fat of lambs of indigenous Greek dairy breeds of sheep, the Boutsko (B), Serres (S) and Karagouniko (K) breed. The lambs (weaned at approximately 42 days) had been reared under different conditions of housing and feeding in three consecutive experiments (Experiment). In Experiment 1, lambs (n=120) were individually penned and fed ad libitum on a concentrate feed (11.3MJ metabolisable energy (ME)/kg DM and 192g crude protein (CP)/kg DM) together with 100g/day of Lucerne hay (8.3MJ ME/kg DM and 182g CP/kg DM). In Experiment 2, lambs (n=108) were fed the same concentrate on 3 different levels: High (H), Medium (M) and Low (L) and ad libitum on Lucerne hay. In Experiment 3, lambs (n=108) were initially group fed indoors for 63 days on 3 different levels of concentrate (H, M and L) together with ad libitum Lucerne hay. Thereafter they were finished on irrigated, sown pasture. Lambs were slaughtered at one of 5 standard proportions of mature weight (PMW) for each breed in Experiment 1 (i.e. 0.20, 0.30, 0.45, 0.60 and 0.90); at 3 fixed live weights in Experiment 2 (TSLW; i.e. 23, 28 and 33kg) and at 3 fixed PMW in Experiment 3 (PMW; i.e. 0.20, 0.48 and 0.54). The right hand side of their carcasses was minced and a random sample, around 200g, was taken. It was freeze-dried and then grounded to obtain a quantity of 2g for lipid extraction and preparation of fatty acid methyl esters, which were assayed by gas-liquid chromatography to identify. Results were analysed separately for each experiment by analysis of variance. In Experiment 1, breed of lambs had significant effects (P<0.001) on C14:0, C16:0, C17:0, C18:2, C18:3 and C18:1 (P<0.05), whereas sex affected only the percentage of C15:0, C16:1 (P<0.001), C18:0 (P<0.01) and C18:2 (P<0.05). Live weight of lambs at slaughter had significant effects (P<0.05-0.001) on all the fatty acids. In Experiment 2, with the exception of C18:0 and C20:0, all other fatty acids were significantly affected by Breed (P<0.05-0.001). However, only C17:0, C18:0, C18:1 and C18:2 were significantly (P<0.001) affected by the level of concentrates in the diet. The major finding in Experiment 3 was the trend for saturated fatty acids to be lower; possibly due to the fact that lambs finished at pasture. It is concluded that there are possibilities of modifying FA composition in carcass fat of lambs by manipulation of post-weaning nutrition and slaughtering them at a wide range of live weights.

Growth and meat quality of kids of indigenous Greek goats (Capra prisca) as influenced by dietary protein and gastrointestinal nematode challenge

The effect of dietary protein and gastrointestinal nematode (GIN) parasitism on growth and meat quality of growing kids was assessed using sixty (60) kids in three groups (n=20); A: control, B: regularly treated with ALBENDAZOLE(®) and C: supplemented with dietary protein. The kids grazed in a pasture contaminated with L3 larvae of GIN. Growth and condition score were assessed at 21-day intervals. After 86days all kids were slaughtered. Carcasses were assessed for conformation, fatness, ultimate pH and other meat quality characteristics. Parasitic challenge was assessed by means of faecal egg counts (FEC), pasture larvae and adult nematodes in the GI tract of kids at slaughter. Groups C and B had higher growth rates and body condition score and produced significantly heavier (P<0.05) carcasses with better (P<0.01) conformation and fatness when compared to those of group A. Total unsaturated and monounsaturated fatty acids were higher (P<0.05) in fat tissue of groups B and C. Group A had the highest FEC and group C had the lowest (P<0.05) FEC. The parasitic challenge of L3 on pasture reached its highest point at 42days and there were significant (P<0.01) differences between the numbers of Teladorsagia spp., Trichostrongylus spp., Haemonchus contortus, Oesophagostomum spp. and Chabertia spp. found in the GI tract of kids between the three groups; group A had the highest numbers. Overall, the results showed that the increased protein content in the diet of growing kids grazing on a pasture contaminated with L3 nematode larvae resulted in the production of acceptable carcasses.

Meat quality of lambs of indigenous dairy Greek breeds as influenced by dietary protein and gastrointestinal nematode challenge

The effect of dietary protein and gastrointestinal (GI) parasitism on growth and meat quality of lambs was assessed using 60 animals. The lambs were randomly allocated to one of three treatment groups (n=20): group A, which served as control, group B that was regularly treated with albendazole and group C, which was given supplementary feeding with dietary protein. The three groups of lambs grazed into a pasture (Lolium perenne), which was contaminated with L(3) larvae of GI nematodes. Lamb growth and condition score were assessed at 21-day intervals. After 126 days grazing all lambs were slaughtered and their carcasses were assessed for conformation and fatness and their ultimate pH was measured. Four carcasses from each group were randomly selected for meat quality measurements including physical analysis as well as colour, moisture, total fat, protein content and fatty acid composition. Parasitic challenge was assessed by means of faecal egg counts of lambs, pasture larvae and numbers of adult nematodes in the GI tract of lambs at slaughter. Growth rate of group B was higher (P<0.01) than that of group A and resulted in significantly (P<0.01) heavier carcasses. The produced carcasses had similar fatness, but differed significantly (P<0.05), in their conformation; carcasses of group C scored higher than either those of group B or group A, respectively. There was a significant difference in the colour attributes (L(∗)) with group A being significantly lighter (P<0.05) and in pH (P<0.01); Group B had the highest values. Carcasses of group C had the highest (P<0.05) amounts of intermuscular fat compared to those of group B and A, respectively. The proportion of C16:1n-7 and C18:2n-6 was higher (P<0.05) in subcutaneous fat tissue whereas the proportion of C18:0 was higher (P<0.05) in muscle tissue. In conclusion, the present results showed that the increased protein content in the diet of growing lambs, grazing on a pasture infected with GI nematode larvae, resulted in the production of acceptable carcasses.