Intra-flock variability in the body reserve dynamics of meat sheep by analyzing BW and body condition score variations over multiple production cycles

Breeding for resilience requires a better understanding of intra-flock variability and the related mechanisms responsible for robustness traits. Among such traits, the animals' ability to cope with feed fluctuations by mobilizing or restoring body reserves (BR) is a key mechanism in ruminants. The objective of this work was to characterize individual variability in BR dynamics in productive Romane ewes reared in extensive conditions. The BR dynamics profiles were characterized by combining individual longitudinal measurements of BW and body condition scores (BCS) over several production cycles. Historical data, including up to 2628 records per trait distributed in 1146 ewes, underwent cluster analysis. Two to four trajectories were observed for BW depending on the cycle, while three trajectories were found for BCS, whatever the cycle. Most trajectories suggested that BR dynamics were similar but the level of BR may differ between ewes. Nevertheless, some trajectories suggested that both BR dynamics and levels were different for a proportion of ewes. Clustering on BW and BCS profiles adjusted for individual level trends, resulted in differences only in the level of BW or BCS, rather than differences in trajectories. Thus, the overall shape of trajectories was not changed considering or not the individual level trend across cycles. In addition to individual variability, the ewe's age at first lambing and litter size contributed to the distribution of the ewes between the trajectories. Regarding the entire productive life, three trajectories were observed for BW and BCS changes over three productive cycles. Increase in BW at each cycle suggested that ewes kept growing up until 3 to 4 years old in our conditions. Similar alternation of BCS gains and losses across cycles suggested BR dynamics might be repeatable. Many individual trajectories remained the same throughout a ewe's life, whatever the age at first lambing, parity or litter size. Our results demonstrate the relevance of using BW and BCS changes for characterizing the diversity of BR mobilization-accretion profiles in sheep in a long timespan perspective.

Use of contrast-enhanced ultrasonographic examination to evaluate health status of mammary glands of ewes at the end of a lactation period

This research communication describes the use of contrast-enhanced ultrasonographic examination (CEUS) in mammary glands of ewes for diagnosis of chronic mastitis; this is the first report of the use of this modality in diagnostic imaging of mammary glands of ruminants. For this purpose, a convex transducer was used, with the following settings: frequency: 2·0/4·0 MHz, mechanical index: 0·09, power: 22 dB, scanning depth: 70 mm, and sulphur hexafluoride in microbubbles at a dose of 20 µl as the contrast agent. In four healthy mammary glands (2 ewes), CEUS examination revealed a steady biphasic pattern of contrast agent kinetics characterised by initial uptake within 15–40 s post-injection, at which time intensity peaked with strong enhancement (130–200 AEU) followed by a gradual wash-out phase. In three mammary glands with history of clinical mastitis (2 ewes), the pattern was particularly inconsistent and unclear, with weak enhancement (<100 AEU) (P < 0·01) lasting for a short period. Notwithstanding issues regarding cost and withdrawal period of contrast-agent, this imaging modality may contribute to improved diagnosis of mastitis cases, especially on occasions when abnormalities cannot be easily confirmed by more conventional methods.

Conditions Associated with Marine Lipid-Induced Milk Fat Depression in Sheep Cause Shifts in the In Vitro Ruminal Metabolism of 1-13C Oleic Acid

Shifts in ruminal oleic acid (OA) metabolism have received little research attention but recent studies have suggested their association with marine lipid-induced milk fat depression (MFD) in ewes and cows. Measurement of specific products of OA within the complex mixture of digesta lipids is however challenging. Therefore, this in vitro trial combined the isotopic labelling technique with the use of rumen inoculum from cannulated sheep fed a diet supplemented or not with 2% of fish oil (which has been demonstrated to cause MFD in dairy ruminants) to characterize the metabolism of OA in response to ruminal alterations associated with MFD. The products of 13C-OA after 24 h of incubation were analysed by gas chromatography-combustion isotope ratio mass spectrometry (GC-C-IRMS). Numerous 13C-labeled 18:1 intermediates and oxygenated FA were detected and no elongation or desaturation of 13OA occurred. Diet supplementation with fish oil (i.e., MFD conditions) resulted in no unique metabolites of 13OA but in relevant changes in the relative contribution of specific metabolic pathways. The inhibition of 18:0 saturation caused by this treatment appeared largely attributable to increased oxygenated FA proportion, in particular the candidate milk fat inhibitor 10-oxo-18:0, and warrants further research on the association between MFD and oxygenated FA. Changes in the concentration of 13C-labeled trans 18:1 intermediates but not in cis 18:1, were also observed.

Changes in fatty acid profile of Bovec sheep milk due to different pasture altitude

Sheep rearing on mountain pastures is an ancestral tradition in northwestern Slovenia. The indigenous Bovec sheep are widespread there and are well adapted to the rough Alpine rearing conditions. Every year, after weaning, the sheep start grazing in the lowlands (L) and then gradually move to mountain pastures, and finally, to the highland (H) pastures of the Alps. Grazing positively affects the fatty acid (FA) composition in sheep milk fat with increased availability of polyunsaturated FA (PUFA) in grass, and subsequently, in milk. Consequently, the objective of this work was to study the FA profile in sheep milk during grazing in four geographical areas in the Alps. A total of 15 ewes of the Bovec sheep breed were randomly selected and milk samples from these ewes were taken at four different pasture locations that differed with regard to altitude: the L pasture location at an altitude of 480 m, the mountain pastures (M1 and M2) at altitudes of 1100 to 1300 m and 1600 to 1900 m, respectively, and the H pastures at altitudes of 2100 to 2200 m. Milk samples from the ewes were taken during the grazing season from April to September. The chemical and FA composition of the milk samples from each pasture location were determined. There were significant differences in the concentrations of FA among the L, M1, M2 and H milk samples. We observed decreases of the concentrations of saturated FA (SFA) in milk from L to H pastures. The concentration of α-linolenic FA, monounsaturated FA (MUFA), PUFA and n-3 PUFA in milk were increased significantly with pasture altitude. The n-6/n-3 PUFA ratio was reduced by the change of pasture altitude with the lowest value at the M1 pasture (1.5). The concentrations of total SFA decreased significantly and was lowest at the L pasture. Our results underline the importance of the effect of grazing in the Alpine region associated with pasture altitude on the FA profile of sheep milk. The first variation in FA concentration in sheep milk occurred between L and M1, although it was more evident on H pastures in the Alpine mountains. Changes of the FA profile in sheep milk due to pasture altitude were related to variation in FA concentration in the pasture and the botanical composition of the pasture location.

Comparison of antioxidant capacity of cow and ewe milk kefirs

This research aimed to evaluate the effects of using either grain or commercial starter culture on the antioxidative capacity of cow and ewe milk kefirs. The antioxidant capacity of kefir samples during fermentation and 21 d of storage was assessed by using 3 assays: 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical cation decolorization; 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) radical scavenging activity assay; and Fe⁺³-reducing power (ferric reducing antioxidant power assay, FRAP). Vitamin E and β-carotene contents were also quantified. All kefir samples exhibited varying values for DPPH, ABTS, and FRAP assays depending on the starter culture and milk type. Vitamin E and β-carotene contents were similar in all kefir samples during storage. The results of this study suggest that milk type (cow or ewe) and culture type (kefir grains or commercial starter) were the significant parameters for the antioxidative activity of kefir.

Genetic parameters for lameness, mastitis and dagginess in a multi-breed sheep population

The objective of the present study was to quantify the extent of genetic variation in three health-related traits namely dagginess, lameness and mastitis, in an Irish sheep population. Each of the health traits investigated pose substantial welfare implications as well as considerable economic costs to producers. Data were also available on four body-related traits, namely body condition score (BCS), live weight, muscle depth and fat depth. Animals were categorised as lambs (<365 days old) or ewes (⩾365 days old) and were analysed both separately and combined. After edits, 39 315 records from 264 flocks between the years 2009 and 2015 inclusive were analysed. Variance components were estimated using animal linear mixed models. Fixed effects included contemporary group, represented as a three-way interaction between flock, date of inspection and animal type (i.e. lamb, yearling ewe (i.e. females ⩾365 days but <730 days old that have not yet had a recorded lambing) or ewe), animal breed proportion, coefficients of heterosis and recombination, animal gender (lambs only), animal parity (ewes only; lambs were assigned a separate 'parity') and the difference in age of the animal from the median of the respective parity/age group. An additive genetic effect and residual effect were both fitted as random terms with maternal genetic and non-genetic components also considered for traits of the lambs. The direct heritability of dagginess was similar across age groups (0.14 to 0.15), whereas the direct heritability of lameness ranged from 0.06 (ewes) to 0.12 (lambs). The direct heritability of mastitis was 0.04. For dagginess, 13% of the phenotypic variation was explained by dam litter, whereas the maternal heritability of dagginess was 0.05. The genetic correlation between ewe and lamb dagginess was 0.38; the correlation between ewe and lamb lameness was close to zero but was associated with a large standard error. Direct genetic correlations were evident between dagginess and BCS in ewes and between lameness and BCS in lambs. The present study has demonstrated that ample genetic variation exists for all three health traits investigated indicating that genetic improvement is indeed possible.

Effect of dam weight and pregnancy nutrition on average lactation performance of ewe offspring over 5 years

The foetal mammary gland is sensitive to maternal weight and nutrition during gestation, which could affect offspring milk production. It has previously been shown that ewes born to dams offered maintenance nutrition during pregnancy (day 21 to 140 of gestation) produced greater milk, lactose and CP yields in their first lactation when compared with ewes born to dams offered ad libitum nutrition. In addition, ewes born to heavier dams produced greater milk and lactose yields when compared with ewes born to lighter dams. The objective of this study was to analyse and compare the 5-year lactation performance of the previously mentioned ewes, born to heavy or light dams that were offered maintenance or ad libitum pregnancy nutrition. Ewes were milked once per week, for the first 6 weeks of their lactation, for 5 years. Using milk yield and composition data, accumulated yields were calculated over a 42-day period for each year for milk, milk fat, CP, true protein, casein and lactose using a Legendre orthogonal polynomial model. Over the 5-year period, ewes born to heavy dams produced greater average milk (P=0.04), lactose (P=0.01) and CP (P=0.04) yields than offspring born to light dams. In contrast, over the 5-year period dam nutrition during pregnancy did not affect average (P>0.05) offspring milk yields or composition, but did increase milk and lactose accumulated yield (P=0.03 and 0.01, respectively) in the first lactation. These results indicate that maternal gestational nutrition appears to only affect the first lactational performance of ewe offspring. Neither dam nutrition nor size affected grand-offspring live weight gain to, or live weight at weaning (P>0.05). Combined these data indicate that under the conditions of the present study, manipulating dam weight or nutrition in pregnancy can have some effects of offspring lactational performance, however, these effects are not large enough to alter grand-offspring growth to weaning. Therefore, such manipulations are not a viable management tool for farmers to influence lamb growth to weaning.

Antioxidant capacity of different cheeses: Affecting factors and prediction by near infrared spectroscopy

In this study, we analyzed antioxidant capacity of 224 cheese samples prepared using 16 varied mixtures of milk from cows, ewes, and goats, in 2 manufacturing seasons (winter and summer), and over 6mo of ripening. Antioxidant capacity was evaluated using the spectrophotometric 2,2-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid) (ABTS) method. Total antioxidant capacity was significantly correlated with season of manufacturing and time of ripening but not with animal species providing the milk. Moreover, statistically significant correlations between the total antioxidant capacity and retinol (r=0.399), fat percentage (r=0.308), protein percentage (r=0.366), K (r=0.385), Mg (r=0.312), Na (r=0.432), and P (0.272) were observed. We evaluated the use of near infrared spectroscopy technology, together with the use of a remote reflectance fiber-optic probe, to predict the antioxidant capacity of cheese samples. The model generated allowed us to predict antioxidant capacity in unknown cheeses of different compositions and ripening times.

Non-dioxin-like Polychlorinated Biphenyls (PCBs) and Chlordecone Release from Adipose Tissue to Blood in Response to Body Fat Mobilization in Ewe (Ovis aries)

Understanding how persistent organic pollutants (POPs) are released from adipose tissue (AT) to blood is a critical step in proposing rearing strategies hastening the removal of POPs from contaminated livestock. The current study aimed to determine in nonlactating ewes whether polychlorinated biphenyls (PCBs) and chlordecone are released from AT to blood along with lipids during body fat mobilization achieved through β-agonist challenges or undernutrition. β-Agonist challenges did not affect serum POP concentrations, whereas serum PCBs 138, 153, and 180 were readily increased in response to undernutrition. After 21 days of depuration in undernutrition, AT PCB 153 and 180 concentrations were increased concomitantly with a decrease in adipocyte volume, whereas AT chlordecone concentration was not different from that observed at the end of the well-fed contamination period. Thus, undernutrition may be of practical relevance for accelerating POP depuration unless it is combined with a strategy increasing their excretion pool.

Transabdominal and transrectal ultrasonography of fetuses in Württemberg ewes: Correlation with gestational age

It is useful to determine the gestational age in sheep to provide essential information for effective flock management practices. The aims of this study were to evaluate the efficacy and practical aspects for using two ultrasound techniques, transabdominal and transrectal, in determining the gestational age in Württemberg ewes. Monitoring of embryo and fetus developmental stages during the ewes' gestation was carried out with real time ultrasound using a transabdominal convex probe, frequency 3.5 MHz, and a transrectal linear probe, frequency 7.5 MHz. The size of the embryonic vesicle during the period from the 23rd to the 38th day of gestation can be used as a confirmational indicator of gestational age when the transrectal probe is used. The occipital nasal diameter correlated with the gestational age with both transabdominal (P < 0.05) and transrectal probes (P < 0.01) from the 46th to the 63rd day of gestation. The biparietal diameter of the fetal head measured by transabdominal probe during the period from the 46th to the 63rd day of gestation correlates with gestation age (P < 0.05). The diameter of the fetal eye orbit monitored by transrectal probe from the 46th to the 63rd day of gestation also correlated well with gestational age (P < 0.05).

Profile of toll-like receptor mRNA expression in the choroid plexus in adult ewes

The blood-cerebrospinal fluid barrier (BCSFB) located in the epithelial cells of the choroid plexus (CP) forms the interface between the cerebrospinal fluid (CSF) and pathogen components circulating in the blood. The CP is also implicated in the passage of peripheral immune signals and circulation of immune cells into the central nervous system. Toll-like receptors (TLRs) are patternrecognition receptors that play a crucial role in the recognition of pathogens and triggering of the innate immune response. In sheep, ten members of the TLR family have been identified and cloned. We used real-time PCR analyses to examine the profiles of TLR mRNA expression in the CP of cerebral ventricles in healthy adult ewes. The transcripts for all ten TLRs except TLR8 were present; however, we observed a high variation in the degree of expression of the TLR5 and TLR1 genes (coefficient of variation: 61% and 46%, respectively) as well as a moderate variation in the expression of the TLR4 (34%), TLR2 (27%) and TLR6 (26%) genes. The TLR9, TLR7, TLR3 and TLR10 genes were the four receptors with relatively invariable expression levels (coefficient of variation: 7%, 8%, 16% and 17%, respectively) across the six adult ewes. The concentration of cortisol in blood collected prior to sacrificing the ewes ranged from 0.18 to 78.9 ng/ml. There was no correlation between cortisol concentration and mRNA expression of any of the examined TLRs. These data suggest that the CP has the potential to sense the presence of many bacterial and viral components and mediate responses for the elimination of invading microorganisms, thereby protecting the brain.

The effects of intravenous, glucose versus saline on ovarian follicles and their levels of some mediators of insulin signalling

BACKGROUND

A short-term increase in food intake and specifically dietary energy can stimulate folliculogenesis and increase ovulation rate in ewes. The mechanism appears to involve the insulin-glucose metabolic system and its interaction with FSH signalling pathways in the granulosa cells of ovarian follicles. This experiment was designed to investigate the interaction between these two systems in the granulosa cells of ovarian follicles.

METHODS

Thirty six Ile-de-France ewes were used in this controlled experiment to study the effects of intravenous glucose on folliculogenesis. Eighteen ewes were infused with glucose (10 mM/h for 72 h) from day 8 of the oestrous cycle, while the others (controls) received saline. Ovaries were collected when the infusions ended (luteal phase) or 30 h later and after a luteolytic dose of a PGF2α analogue (follicular phase). Follicles were dissected and granulosa cells and follicular fluid harvested. The blood concentrations of glucose, insulin, oestradiol and FSH were monitored over the experiment. The levels of Aromatase P450 and of the phosphorylated and non-phosphorylated forms of Akt, AMPK and ERK in granulosa cells and the concentration of oestradiol in follicular fluid, were determined.

RESULTS

Glucose increased the circulating concentration of glucose (P < 0.05) and insulin (P < 0.05). It also increased the total number of follicles >1.0 mm in diameter (P < 0.05) and small (P < 0.05) follicles (>1.0 to 2.0 mm in diameter) but not medium (>2.0 to 3.5 mm in diameter) or large (>3.5 mm in diameter) follicles. Glucose decreased circulating oestradiol (P < 0.05) but not that of FSH or progesterone. Glucose reduced aromatase P450 (P < 0.05) and decreased the phosphorylation of Akt (P < 0.05), ERK (P < 0.05) and AMPK (P < 0.05) in granulosa cells from oestrogenic follicles. The level of Aromatase P450 was greatest in large oestrogenic follicles and the phosphorylation of Akt (P < 0.05), ERK (P < 0.05) and AMPK (P < 0.05) was lower in small follicles compared to medium and large follicles.

CONCLUSIONS

These data suggest that the effect of glucose in small follicles is a direct action of glucose that increases the number of small follicles while the effect of glucose in oestrogenic follicles is an indirect insulin-mediated action.

essential oils supplementation on digestion, colostrum production of dairy ewes and lamb mortality and growth

The aim of this study was to evaluate the effect of rosemary essential oils (REO) and the forage nature on ewes' performances, immune response and lambs' growth and mortality. Forty-eight dairy ewes (Sicilo-Sarde) were fed oat-hay or oat-silage supplemented with 400 g of concentrate during pregnancy and 600 g during postpartum. The experimental concentrate contained the same mixture as the control (barley, soybean meal and mineral vitamin supplement) more 0.6 g/kg of REO. Two groups were obtained with each forage (Hay groups: H-C and H-REO; Silage groups: S-C and S-REO). REO increased the dry matter (DM) intake, the nitrogen intake and retention being higher with the silage groups (P < 0.05). REO increased solid non-fat (P = 0.004) and fat contents of colostrum which was higher with hay (P = 0.002). REO decreased lamb mortality (P < 0.05) which averaged 21% for control groups and 6% for H-REO, while no mortality was recorded with S-REO. REO dietary supply improved forage intake and tended to ameliorate colostrum production; it could be a natural additive to improve ewes' performances.

Induction of cervical dilation for transcervical embryo transfer in ewes

BACKGROUND

A major limitation in the application of assisted reproductive technologies in sheep arises from the inability to easily traverse the uterine cervix. The cervix of the non-pregnant ewe is a narrow and rigid structure, with 5-7 spiral folds and crypts that block its lumen. The first two folds closest to the vagina appear to be the greatest obstacle for the instrument insertion into the sheep cervix. Therefore, the dilation of the distal part of the cervix could provide the conformational change necessary to perform non-invasive transcervical procedures. The present study set out to assess the efficacy of Cervidil®, a patented dinoprostone (PgE2)-containing vaginal insert with a controlled-release mechanism, to safely induce sufficient cervical dilation for the purpose of transcervical embryo transfer (TCET) in cyclic ewes.

METHODS

The transfer of frozen-thawed ovine embryos was attempted in 22 cross-bred Rideau Arcott x Polled Dorset ewes, with or without the pre-treatment with Cervidil® for 12 or 24 h prior to TCET.

RESULTS

Cervical penetration rate was significantly improved after Cervidil® pre-treatment, with 55% (6/11) of treated versus 9% (1/11) of control animals successfully penetrated (χ2-test, p < 0.05). Within the treated ewes that were penetrated, 67% (4/6) had been exposed to Cervidil(R) for 24 h and 33% (2/6) had had a 12-h exposure (p > 0.05). Variations in the age, weight, genotype, parity, lifetime lamb production (LLP) and post-partum interval (PPI) between penetrated and non-penetrated ewes were not significant (p > 0.05). The time taken to traverse the uterine cervix was negatively correlated (p < 0.05) with the age, parity, LLP and PPI. Progesterone assays and ultrasonographic examinations performed 25 days after ET confirmed pregnancy in 2 of 7 penetrated ewes, but no fetuses were detected ultrasonographically 55 days post-TCET.

CONCLUSIONS

The present results indicate a significant benefit of using Cervidil® for inducing cervical dilation during the mid-luteal phase in ewes but the reason(s) for impaired fertility after the transfer of frozen-thawed ovine embryos remains to be elucidated.

Follicular expression of follicle stimulating hormone receptor variants in the ewe

BACKGROUND

Several alternatively-spliced mRNA transcripts of the follicle stimulating hormone receptor (FSHR) have been identified in sheep, including FSHR-1 (G protein-coupled form), FSHR-2 (dominant negative form), and FSHR-3 (growth factor type-1 form). Our objective was to determine which of these variants is predominantly expressed in follicles collected from ewes at various times after estrus.

METHODS

Suffolk-cross ewes (n = 8) were allowed to come into estrus naturally and were euthanized 24 (n = 3), 36 (n = 3), or 48 (n = 2) hours after the onset of estrus. All visible follicles were measured, aspirated and pooled according to follicular diameter: small (<= 2.0 mm), medium (2.1-4.0 mm), large (4.1-6.0 mm), and preovulatory (> = 6.1 mm). Aspirated cells were separated from follicular fluid by centrifugation. Total RNA was extracted from cell pellets and reverse transcribed. The resulting cDNA was subjected to qPCR, using primer sets designed to amplify each variant specifically. Gene expression was normalized to that of beta-actin within samples, and compared by analysis of variance with the level of significant differences set at p < .05.

RESULTS

Relative expression of FSHR-3 exceeded that of both FSHR-1 and FSHR-2 in medium follicles, and tended to be higher in small follicles (p = .09) regardless of time after onset of estrus, and thus results from different time points were pooled. Expression of FSHR-3 was greater than that of FSHR-2 and luteinizing hormone receptor (LHR) in small and medium follicles. Expression of LHR was greatest in preovulatory follicles.

CONCLUSIONS

These experiments show that in addition to the well characterized G protein-coupled form of the FSHR, alternatively spliced variants of the FSHR may participate in follicular dynamics during follicular waves of the sheep estrous cycle. Furthermore, these results indicate that an "alternatively" spliced form of the FSHR (FSHR-3) is the predominant form of the FSHR in the sheep.

Heavy metals in raw cow and ewe milk from north-east Iran

The presence of toxic metals in milk may create significant health problems for the population. In this study, 1440 raw cow and ewe milk samples from 18 townships in north-east Iran were analysed in four different seasons. Lead, cadmium and mercury levels were determined using atomic absorption spectrophotometry. Mean concentration of lead, cadmium and mercury in cow milk samples was 12.9 ± 6.0, 0.3 ± 0.3 and 3.1 ± 0.3 ng g⁻¹, respectively, and in ewe milk samples, these mean values were 14.9 ± 7.8, 1.6 ± 1.2 and 3.1 ± 0.3 ng g⁻¹, respectively. Statistical analyses showed that lead and cadmium concentrations in ewe milk were significantly higher than in cow milk. Concentrations of these metals in ewe milk varied significantly with different seasons. As the concentrations did not exceed the safety limits, they could not pose a serious danger to public health.

Abnormal position of lymph nodes in a freemartin sheep

In this freemartin case report the authors present the clinical and morphological findings of a freemartin ewe with an abnormal position of two lymph nodes. Freemartins, infertile females from mixed-sex twin pregnancies, are chimeras, having two cell populations: one of their own (XX DNA) and one from their male twin (XY DNA). Freemartins can have varying degrees of phenotypic masculinization, including, in some cases, having active male gonads and exhibiting male behaviors such as heat detection and aggressiveness. During the clinical examination of the freemartin ewe, a morphological abnormality of the vulva, the presence of scrotal sacs, and a lack of mammary tissue development were noted. On inspection of the vaginal channel, an extremely enlarged clitoris, resembling a penis, was found. The clinical evidence suggested freemartinism. After the karyotyping diagnosis confirmation, a necropsy was performed and samples were taken for histology and immunohistochemistry. There were two structures found in the scrotal sacs; however, these were found to be lymph nodes, not testicles, and this was confirmed by CD3 lymph protein coloration. On histological study, the phallic structure showed corpus cavernosum and tunica albuginea. The testicles were found retained inside the abdominal cavity, with the presence of atrophic seminiferous tubules. Although the position of the testicles in freemartins has been reported as highly variable, this is the first time, to the best of the authors' knowledge, that a case has been reported where lymph nodes have been found inside the scrotal sacs. It is possible that these were the inguinal lymph nodes, trapped inside the scrotum during fetal growth and development.

Involution of the sheep mammary gland

Changes in the ovine mammary gland epithelium during initiated involution were studied by light and electron microscopy. Apoptosis of the duct and alveolar epithelial cells was first identified at 2 d after weaning, reached a peak at 4 d and then progressed gradually thereafter. Apoptotic cells were phagocytosed by intraepithelial macrophages and alveolar epithelial cells. Occasional apoptotic epithelial cells were observed in the alveolar and duct lumina. The highly vacuolated cells in the alveolar and duct lumina were confirmed to be macrophages as they were CD45+, MHC class II+. Changes in myoepithelial cells involved shrinkage and extension of cytoplasmic processes into the underlying stroma and no apoptosis was observed. Regression of the blood capillaries was also by apoptosis. The resulting apoptotic bodies were either taken up by adjacent endothelial cells or were shed into the capillary lumen to be phagocytosed later by mural endothelial cells or blood monocytes. The mammary glands were completely involuted by 30 d after weaning. It was concluded that the mammary gland involutes by apoptosis, a process which allows deletion of cells without the loss of the basic architecture and the integrity of the epithelial lining of the gland.