Bone metabolism of milk goats and sheep during second pregnancy and lactation in comparison to first lactation

Substantial losses of skeletal tissue occur during late pregnancy and lactation. The goal of the present study was to follow these changes in pregnant and lactating goats and sheep, compare these two species during their second lactation, and also compare the results to the first lactation. Blood samples were collected from 12 adult dairy goats (Saanen goat) and sheep (Ostfriesen milk sheep) monthly during gestation, 2 or 3 days postpartum (pp), 2 weeks pp, 4 weeks pp, and then monthly during lactation until 7 months after parturition. Total bone mineral content (BMC) and total bone mineral density (BMD) were quantified using peripheral quantitative computed tomography (pQCT) at the same intervals as the blood was taken. Bone resorption was assessed in serum using two different domains of the carboxyterminal telopeptide of type I collagen (ICTP and crosslaps). Bone formation was quantified in serum with osteocalcin (OC) and bone-specific alkaline phosphatase (bAP). In addition, Ca and 1,25 dihydroxy vitamin D (VITD) were determined in serum. The same procedure was done during the first and second gestation and lactation. Mean ICTP and crosslaps concentrations of the two animal species showed an increase in the last month of gestation. In contrast, mean OC concentrations decreased slowly from the 2nd month of pregnancy until the first week pp. Also mean bAP activities showed a similar time course. Total BMC and BMD decreased until the first week pp in both species. Afterwards, BMC increased again during lactation. BMD levels of sheep and goats returned to prepartum levels during lactation. Vitamin D concentrations peaked in the first week pp. Only VITD concentrations in goats stayed elevated compared with prepartum values throughout the whole lactation during the second lactation. Around parturition and at the beginning of lactation, the bone resorptive phase of bone remodelling is accelerated, but is uncoupled from the process of bone formation. The mineral decrease in bone of these lactating animals seems to be reversible. Since during lactation, bone remodelling has bone resorption and formation phases tightly coupled. Interestingly, in these species, the bone loss in the second pregnancy and lactation measured with BMC and BMD is not as prominent as in the first lactation, but shows almost the same course, although the animals gave more milk in the second lactation. It seems that the organism adapts to the circumstances more easily in the second lactation compared to the first lactation in these two species.     

Vitamin D receptor amounts across different segments of the gastrointestinal tract in Brown Swiss and Holstein Frisean cows of different age

During different stages of lactation, different requirements of calcium have to be met depending on the milk amount. Vitamin D receptors (VDR) regulate calcium homeostasis by increasing the entry of Ca into blood from bone stores and dietary sources. The purpose of this study was to investigate if age and breed of cows influence VDR amounts across different segments of the gastrointestinal tract. Thirty-six cows were used (18 Brown Swiss, 18 Holstein Friesan, both > 5.5 years or < 4.5 years). Tissue specimens of the intestines were collected from the cows. Formaldehyde-fixed and microwave-treated paraffin sections were used for VDR immunohistochemistry employing a biotinylated monoclonal rat antibody and streptavidin peroxidase technique. The results showed that nuclei and cytoplasm of enterocytes stained positively for VDRs. Strongest immunoreactions were observed in intermediate and basal glandular cells. No significant differences were observed between the different groups. Vitamin D receptors immunoreactivities were prominent in duodenal mucosa, lower in jejunum and in colon, decreased further in ileum and were lowest in caecum. Decreases in number of positively marked cells and staining intensities resulted in reduced immunoreactions. The results of this study indicate that VDR are highly expressed at the site of maximal intestinal calcium absorption. No significant influence of age and breed was observed. The animals used were not in a negative Ca balance. The cows were all in the stage of late or mid lactation. During these periods, the Ca requirements are low and the diets are high in Ca concentration; and the animals are adapted to these circumstances. Passive absorption in adult animals seems to dominate when Ca intake is adequate or high. The active absorption may play a considerably more significant role during the peripartal period, when Ca homeostatic mechanisms are challenged because of tremendous Ca demand at the initiation of lactation.     

基于Meta分析的母羊泌乳模型构建及泌乳性能预测

母羊泌乳量不仅关乎母羊自身营养需求,也是影响羔羊生长发育的重要因素,准确预测母羊泌乳量在母羊和羔羊精准饲养中具有现实意义。本文利用方差倒数Meta分析方法研究母羊泌乳曲线模型及泌乳参数,并对其泌乳性能进行预测。分别在Web of Science、CNKI等文献数据库中检索母羊泌乳曲线及影响因素的相关文献,依据纳入标准筛选和提取泌乳曲线相关参数,采用方差倒数Meta分析方法进行合并,综合评估母羊泌乳曲线及其影响因素。共纳入文献22篇,提取数据98条。结果显示：山羊泌乳曲线模型为y=0.943 8t^{0.359 9}e⁽(-0.008 5t)),绵羊为y=0.677 2t^{0.349 4}e⁽(-0.014 0t)),乳用山羊为y=1.143 7t^{0.318 7}e⁽(-0.008 0t)),非乳用山羊为y=0.419 0t^{0.468 1}e⁽(-0.011 8t)),乳用绵羊为y=0.796 8t^{0.256 2}     

Effect of vitamin E supplementation of sheep and goats fed diets supplemented with polyunsaturated fatty acids and low in Se

Vitamin E (VitE) and selenium (Se) are an essential part of the antioxidative functions of metabolism. There are situations of low supply of both micronutrients. As VitE is involved in ruminal biohydrogenation of polyunsaturated fatty acids (PUFA) and their protection against oxidation in metabolism, diets supplemented with PUFA may challenge VitE to an extent making recommended supplies insufficient. Twelve goats and sheep each were fed a diet supplemented with PUFA and characterised by low Se and limited VitE contents during the last 2 months of gestation and the first 2 months of lactation. The basal diet consisted of hay and concentrate. Six goats and sheep received extra VitE, while the control groups received no extra VitE. Blood and milk samples were taken. In addition, liver, heart muscle and spleen samples were obtained from the offspring after slaughtering at an age of 8 weeks. No significant changes were observed in serum Se and VitE. A significant increase in serum VitE concentrations between 2 and 4 weeks postpartum (pp) was evident in the supplemented kids. In 4, 6 and 8 weeks pp, the serum concentrations of VitE in the supplemented kids were significantly higher compared to the unsupplemented group. In the kids, VitE was higher in liver of the supplemented groups. There were no significant differences in response to extra VitE between sheep and goat. The kids responded to serum VitE different from that of lambs, as a significant difference was observed between supplemented and unsupplemented animals in the goat kids, but not the lambs. In conclusion, goats and sheep have to be viewed differently and may not be considered alike relating to VitE/Se metabolism and requirements, especially in young animals.     

Nutrition and optimum performance of dairy goatsAlimentation et performances optimales des chèvres laitièresFütterung und optimale leistungen bei milchziegen

The main feeding factors leading to optimum milk production in dairy goats are studied in this paper. Because of its high milk yield, the goat consumes large quantities of dry matter. Accordingly, the intake of energy seems to be the most important dietary factor influencing milk production.The amount of concentrates offered must be determined according to the type and the quality of forages. For obtaining maximum production the energy density of the diet must approximate 0.80 F.U./kg D.M.The annual feeding programme of the dairy goat must be adapted to its behaviour and must take into account its physiological status. Before and after parturition, feeding of good quality forages favourably affects the onset of lactation. The supply of concentrates before parturition should not exceed about 8 g D.M./kg L.W. After parturition, the increase in the concentrate intake of the goats should not be too rapid. In the middle of lactation and especially at the end of lactation, maintenance of milk production at a high level requires a slightly higher supply of concentrates than that necessary to meet the requirements for energy.     

Parturient paresis and hypocalcemia in ruminant livestock

Parturient paresis (hypocalcemia) is most likely to affect dairy cattle around the time of parturition. It causes progressive neuromuscular dysfunction and flaccid paralysis. Older dairy cows, cows with a history of parturient paresis during a previous lactation, high-producing cows, and cows from the Jersey and Guernsey breeds are at highest risk for developing parturient paresis. Nonparturient hypocalcemia may also occur and is related to events other than parturition, such as severe stress, that temporarily overwhelm the mechanisms of calcium homeostasis. Beef cattle, sheep, and goats are affected less frequently by hypocalcemia than are dairy cows. Because these species are not as stressed for milk production as dairy cattle, nonparturient hypocalcemia makes up a higher proportion of cases in nondairy ruminants. Clinical signs of hypocalcemia in beef cattle, sheep, and goats tend toward hyperesthesia and tetany rather than the classic flaccid paralysis that occurs in dairy cattle with parturient hypocalcemia. Prompt and effective treatment of hypocalcemia helps to reduce the incidence of secondary complications, such as muscle damage or mastitis. The standard treatment regimen of 500 ml of 23 per cent calcium gluconate, administered intravenously, will elicit a favorable response in approximately 75 per cent of recumbent cows within 2 hours of treatment. Relapses following successful initial therapy are common and may be prevented in part by supplementation of intravenous treatment with an additional 500 ml of 23 per cent calcium gluconate administered subcutaneously. Proper nursing care following treatment speeds recovery and reduces the incidence of secondary complications owing to hypocalcemia.     

Lactation and fertility in goats after the induction of parturition with an analogue of prostaglandin F2 alpha, cloprostenol

Cloprostenol, 100 micrograms, given intramuscularly to the nanny, with 50 micrograms 10 hours later, precipitated parturition in goats after 36 +/- 1 hours (mean +/- SEM), when administered at 137 +/- 0.5 days gestation. All kids were born alive and survived to weaning. Milk yield over 40 weeks post partum was not significantly different from that after spontaneous parturition. Three hundred micrograms cloprostenol (200 micrograms with 100 micrograms 10 hours later) also initiated parturition at 137 +/- 0.5 days gestation but caused a significant (P less than 0.01) suppression of lactation. Cloprostenol-induced parturition in more than one pregnancy had no adverse effects except for an increased incidence of placental retention, which was treated successfully with intrauterine pessaries containing oestrogen. During the first eight days after spontaneous parturition efficiency of milk secretion was inversely related to udder mass, suggesting a gradual maturation of the secretory alveolar epithelium over this time. When parturition was induced by cloprostenol there was a four to eight day delay before the establishment of this relationship which appeared essential for a successful lactation. Cloprostenol proved to be a useful tool for the control of parturition in goats, having applications to both general animal husbandry and for the study of mammary development and secretory competence.     

Influence of different calcium contents in diets supplemented with anionic salts on bone metabolism in periparturient dairy cows

At the initiation of lactation, Ca homeostatic mechanisms have to react to a tremendous increase in demand for Ca. Mobilization of Ca from bone and increased absorption from the gastrointestinal tract are required to re-establish homeostasis. It has been shown that dietary anions play an important role in the prevention of milk fever by mobilizing Ca from bone and by increasing Ca absorption in the GI tract. The purpose of the present study was to investigate the influence of different Ca contents in diets supplemented with anionic salts on bone metabolism of dairy cows. Twenty-four holstein cows (housed inside, second to fourth lactation) without a milk fever history were divided into four groups (A, B, C, D). Each group was fed a different diet which was given from day 263 of gestation till the day of parturition. Group A and B received a low calcium diet (4 g/kg DM) whereas group C and D received a high Ca diet (8 g/kg DM). In addition group B and D received anionic salts. The DCAD was calculated with the formula: DCAD (mEq/kg DM)=(0.2 Ca2++0.16 Mg2++Na++K+)-(Cl-+0.6 S2-+0.65 P3-). Blood and urine samples were collected on days 256, 270 and 277 of gestation, on the day of parturition as well as the following 5 days and on days 9, 14 and 19 after parturition. Serum Ca, P, Mg, ICTP, OC, VITD, PTH and urinary pH were analysed. The bone resorption marker ICTP showed a significant increase after parturition in all the groups. On the contrary, the bone formation marker OC decreased after parturition in all the groups. The VITD concentrations in group D and the urinary pH in group B were significantly lower compared to the other groups (p<0.05). The Ca concentrations tended to be higher in group B around parturition than in all the other groups. No significant influence of the four different diets on all the other parameters could be shown. In conclusion, this data showed that the addition of anions and the different Ca contents had no significant influence on bone resorption and bone formation markers. This may be because of the fact that the dietary cation-anion balance was not low enough (DCAD-group A: 181 mEq/kg DM, group B: -48 mEq/kg DM, group C: 210 mEq/kg DM and group D: 28 mEq/kg DM) to induce a metabolic acidosis with all its positive effects on calcium metabolism.     

The effect of gestation and lactation on bone calcium, phosphorus and magnesium in dairy cows

A study was conducted to monitor changes in cortical bone mineral in the dairy cow in response to demands of lactation and pregnancy using rib bone biopsies in serial sampling. Sixteen Friesian cows from the University dairy herd were used to collect 9 samples during the lactation period and 5 samples during the dry period. The data were analysed using a split-plot design analysis of variance. There were no significant (P > 0.05) differences in cortical bone phosphorus concentrations in rib bone during the lactation period, but calcium concentrations in cortical bone were significantly (P < 0.05) higher at parturition and during the first 30 days of lactation compared to the next 30 days and between 90 and 120 days. Results reported here indicate that the cow resorbs cortical bone during the middle of the lactation period and not during the periparturient period as previously thought. Magnesium concentrations were also significantly (P < 0.05) higher at the beginning of lactation compared to some of the other sampling times, but cortical bone was significantly (P < 0.05) thinner at the beginning of lactation compared to several of the other sampling times. There were no significant (P > 0.05) differences in cortical bone Ca or Mg concentrations during the gestation period. Cortical bone P concentrations significantly (P < 0.05) decreased during the first 180 days, but significantly (P < 0.05) increased at 181-230 days and significantly (P < 0.05) decreased again at 231 days to term. Cortical bone thickness decreased significantly (P < 0.05) from the beginning of gestation to term. There were no significant (P > 0.05) differences in cortical bone thickness or Ca or Mg concentrations in cortical bone during the dry period, but cortical bone P concentrations were significantly (P < 0.05) greater at the end of the dry period compared to the first 30 days of the period. In general, cortical bone Ca and Mg values decreased as milk production increased up to 20 kg/day and cortical bone P values and bone thickness increased. In animals producing over 20 kg/day, however, cortical bone mineral values were greater and cortical bone thickness was lower compared to those animals producing less than 20 kg.     

西农萨能奶山羊泌乳期产奶量、乳成分及血液生理生化指标变化规律研究

旨在探索西农萨能奶山羊泌乳期生产性能、乳成分、血液生理生化指标和营养物质摄入量等变化规律及其相互关系.本研究选取15只体重、胎次、产奶量、分娩日期相近,体况健康的西农萨能奶山羊.单圈饲喂54周,试验期内准确测定个体生产性能、乳成分、血液生理生化指标和营养物质摄入量等,建立各项指标随泌乳期变化规律模型及泌乳期内指标间的相...     

东佛里生羊、湖羊及东湖杂交羊的泌乳性能比较分析

【目的】本研究旨在探索东佛里生羊、湖羊及东湖杂交羊的泌乳性能。【方法】选取同一养殖场健康东佛里生羊(DF)、湖羊(H)、东湖杂交一代(F1)、级杂二代(F2)各197、313、346、364只。收集其在2020—2021年间的日泌乳量数据,使用六次多项式拟合泌乳曲线,估计泌乳曲线参数;采集奶样,用乳品分析仪测定乳脂、乳蛋白、乳糖、总固形物和尿素氮;对奶绵羊乳房拍照进行形态学描述,测量乳头形态数据,包括乳头长度、乳头间距和乳头直径;麻醉后采集空怀期乳腺组织,制作组织切片,苏木精-伊红(HE)染色后镜检。【结果】东佛里生羊泌乳量显著高于杂交一代(P<0.05),东佛里生羊与级杂二代泌乳量差异不显著(P>0.05),杂交一代与级杂二代泌乳量均显著高于湖羊(P<0.05)。使用六次多项式模型拟合不同杂交代奶绵羊泌乳曲线,拟合度均高于0.90。东佛里生羊、湖羊、杂交一代、级杂二代泌乳高峰日分别为58、18、45与47 d,泌乳高峰日泌乳量分别为2.31、1.27、2.24和1.97 kg。湖羊乳脂含量显著高于其他杂交代奶绵羊(P<0.05),东佛里生羊与杂交一代乳蛋白含量...     

Searching for DNA markers for milk production and composition on chromosome 6 in sheep

Several milk protein polymorphisms are potential tools for selection in dairy ruminants. However, research results for dairy sheep are not as conclusive as those for goats or cattle and are often controversial. The main objective of this study was to find and later use molecular genetic markers in selection to improve milk production and milk composition in Awassi ewes. Chromosome 6 was chosen because several studies have reported the presence of significant quantitative trait loci (QTL) affecting milk production traits on ovine and bovine chromosome 6. Altogether, genotypes for 13 microsatellite loci were determined for 258 ewes, which were purebred Awassi or Awassi-Merino crosses. Phenotypic data were lactation yield of milk, milk fat, protein and lactose (kg), average milk protein and fat percentage and average somatic cell count. Five out of the 13 microsatellites showed significant association with at least one of the examined traits.     

Pre-parturition staphylococcal mastitis in primiparous replacement goats: persistence over lactation and sources of infection

This investigation reported for the first time the occurrence of intramammary infections caused by Staphylococcus in primiparous replacement goats before parturition and the persistence of clinical Staphylococcus aureus infection during the lactation period. Subclinical infections, mainly caused by coagulase negative staphylococci (CoNS), did not persist during lactation. Genotyping analysis indicated that environment seems to play a moderate role as source of intramammary infections to goats before parturition, but causative agents of mastitis in lactating animals are not genotypically related to environmental staphylococci. The occurrence and persistence of intramammary infections in replacement goats demonstrate the need to consider those animals as potential sources of infections in dairy goat herds.     

Effects of coumestrol administration to maternal mice during pregnancy and lactation on renal Ca metabolism in neonatal mice

The present study was conducted to clarify the effects of coumestrol administration to maternal mice during pregnancy and lactation on serum Ca and Ca metabolism in their neonatal mice. From 6.5 to 16.5 days post coitus and from 3 to 10 days after parturition, maternal mice were administered at 200 µg/kg body weight/day of coumestrol. Coumestrol administration did not affect weight gains, serum Ca and the expression of vitamin D receptor (VDR) protein in the kidney of neonatal mice, but weight gains of maternal mice were decreased by coumestrol administration. Coumestrol administration increased the messenger RNA (mRNA) expressions of epithelial Ca channels 1 (ECaC1) and VDR in the kidney of neonatal mice, and also increased the mRNA expressions of ECaC2 in the kidney and small intestine of male neonatal mice. The mRNA expressions of ECaC1, ECaC2, calbindin‐D_9k (CaBP‐9k) and estrogen receptor (ER)α in the kidney and VDR in the small intestine of male neonatal mice were higher than those of female mice. Thus, coumestrol administration to maternal mice during pregnancy and lactation may affect renal Ca metabolism in neonatal mice, especially male neonatal mice via maternal milk.     

Induction of parturition in dairy cattle and its effects on health and subsequent lactation and reproductive performance

OBJECTIVE: To determine the effect of induction of parturition on health, milk production and reproductive performance of dairy cows. DESIGN: A prospective cohort study in 62 dairy herds. PROCEDURE: Health, milk production and fertility indices were documented for 1449 dairy cows treated with dexamethasone trimethylacetate, with or without prostaglandin to induce calving. Equivalent data was collected for 603 untreated herd mates that calved at approximately the same time. RESULTS: The median interval from initial treatment to calving was 11 days. Induction was associated with a substantially lower calf survival and commercial value of surviving calves. Calf viability and value was lower when induced cows were at an earlier stage of pregnancy. Retained foetal membranes, photosensitisation and other problems were significantly more frequent in the induced group compared to the untreated group. Milk production of induced cows was approximately 4% lower than untreated ones, but the majority of reproductive indices were not significantly different between the two groups. CONCLUSIONS: The practice of induction of parturition in seasonal calving dairy herds is a reliable way of shortening the gestation period of cows. Costs associated with morbidity and mortality of induced cows and losses in lactation and calf production are offset by benefits of improved reproductive performance and more efficient management of the herd. The welfare aspects of induction on calf survival must be considered.     

和田多胎红羊泌乳规律初步研究

本研究旨在探明和田多胎红羊泌乳规律,提高双羔成活率。选取6只产双羔和田多胎红羊母羊为试验动物,检测其产后1~28 d泌乳量、乳成分变化规律;测量产后第1天母羊乳房体尺指标,并与泌乳量进行相关性分析。结果显示,和田多胎红羊产后1~28 d总泌乳量为29.87 kg,平均每日泌乳量为1.07 kg,泌乳量在第1~3天上升速度最快,在第21天达到峰值1.23 kg,泌乳曲线方程为：y=537t^0.477e^-0.033t;乳脂、非脂乳固体、密度、乳糖、固形物、蛋白质指标在和田多胎红羊母羊产后1~3 d快速下降,7~28 d趋于稳定,且6项指标第1天与第7、14、21、28天均差异极显著（P<0.01）;和田多胎红羊母羊产后第1天与第14、21、28天的泌乳量之间相关性不显著（P>0.05）,产后第2天与第28天的泌乳量相关性不显著（P>0.05）,其他均显著相关（P<0.05）;母羊产后第1、2、3、7天泌乳量与乳房宽呈显著相关（P<0.05）,母羊产后第14、21、28天泌乳量与乳房体尺指标相关性不显著（P>0.05）。以上研究结果为和田多胎红羊新类群种质特性、选育、饲料配制、羔羊早期断奶等提供理论依据。     

Pregnancy increases plasma leptin in nulliparous but not primiparous goats while lactation depresses it

Most dairy ruminants are still lactating during early pregnancy, which could induce hormonal adaptations different from those observed during pregnancy alone. The incidence of concomitant lactation and pregnancy on plasma leptin has not been studied, and physiological factors involved in its regulation have not been addressed in goats. We assayed leptinemia throughout the pregnancy-lactation cycle in nulliparous and primiparous goats, starting 165 days prior to parturition and finishing 59 days after. During the first half of pregnancy, primiparous goats were lactating. Lactating non-pregnant primiparous goats were studied in parallel. Plasma leptin increased (+49%) up to mid-pregnancy in nulliparous, but not in primiparous goats. Furthermore, leptinemia was similar between pregnant and non-pregnant lactating primiparous goats, suggesting a strong leptinemia down-regulation by late lactation. Plasma leptin decreased from mid-pregnancy to parturition, more markedly in nulliparous goats, and remained depressed during early lactation at a similar level in both female types. It was lower, at 130 days of pregnancy, in goats carrying two fetuses. The leptinemia down-regulation by late pregnancy was highlighted by the lack of plasma leptin increase after drying-off late-pregnant primiparous goats, while it strongly increased in non-pregnant goats. The observation of leptinemia increase only in nulliparous goats suggests that it is not an essential endocrine adaptation during early pregnancy. By contrast, in both female types, the low leptinemia during transition from late pregnancy to lactation, and during late lactation, may be important for the adaptations that occur during lactation such as the partitioning of energy and nutrients towards essential functions and/or hyperphagia.     

繁奶康对奶牛泌乳早期泌乳性能及血液指标的影响

选择20头荷斯坦高产牛,采用配对分组设计分为对照组和试验组,每组各10头。对照组使用原日粮,试验组产前21d每天在日粮中添加繁奶康125g,于分娩当天添加量增至300g直到试验结束,以探讨日粮添加繁奶康对奶牛泌乳早期产奶性能(产奶量及乳品质)的影响。结果表明,补充繁奶康,产奶量、乳脂校正乳产量试验组明显高于对照组(P0.05);奶牛采食量、乳脂率、乳蛋白率、乳糖率及乳干物质含量两组间差异不显著(P0.05)。血液指标谷草转氨酶、谷丙转氨酶活性两组间无显著差异(P0.05),高产奶牛补充繁奶康对泌乳早期产奶性能有较好的改善作用。     

奶山羊乳房温度与体内外温度、泌乳性能的相关性研究

[目的] 随着奶山羊养殖行业的发展,规模化、集约化程度不断提高,如何能更便捷地对奶山羊的健康状况和生产性能进行有效评判,是提高奶山羊养殖效率的重要措施。[方法] 本试验通过测定奶山羊体内外温度、产奶量以及乳成分,分析乳房温度与体内外温度以及与泌乳性能之间的相关性。[结果] 发现乳房温度与舍温、额温有明显的相关性（P<0.01）,但与眼温和肛温之间没有显著相关性;此外,乳脂、非乳脂固形物与乳房温度之间也存在显著的相关性（P<0.01）。[结论] 乳房温度是一个很好的评价指标,可适宜地用于监测奶山羊健康状况和生产性能。     

Concentration of conjugated linoleic acid in grazing sheep and goat milk fat

The conjugated linoleic acid (CLA) content of grazing sheep and goat milk fat, throughout their lactation period, was examined. Six sheep and six goat representative farms were selected at random and milk samples were taken at monthly intervals for fatty acids profile determination. Sheep and goat nutrition was based on natural grazing and on supplementary feeding during the winter months. From April onwards, grazing native pastures was the only source of feed for sheep and goats. The University farm whose sheep are kept indoors all year round without any grazing, was also used as reference. Fifteen individual milk samples were also taken in April from a sheep and goat farm respectively, in order to see the variability of CLA inside the farm. The results showed that: a. the CLA content of grazing sheep and goat milk fat increased significantly in April–May (early growth stage of grass) and then declined while that of indoors kept sheep was more or less constant during the same period, b. the isomers cis-9, trans-11 and trans-10, cis-12 of CLA were found in grazing sheep milk fat, while in indoors kept sheep and goats' milk fat only the cis-9, trans-11 isomer was found, c. the CLA content of sheep milk fat was much higher than that of goats, d. a negative correlation between sheep milk fat and CLA content was found and e. there was considerable variation in milk fat CLA content between sheep and goat farms and inside the farms.