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The effect of cryopreservation on boar sperm viability, motility, lipid content and antioxidant enzymatic activities was studied. Three classes of semen were determined according to a cluster analysis on the basis of the proportion of live and dead cells after freezing and thawing. The classes identified were: high (H, n = 4), average (A, n = 12) and low (L, n = 3) viability. The concentration of sperm cells decreased from class H to A to L. Fresh semen samples with higher viability and a higher proportion of motile cells also maintained better quality after the freezing and thawing procedure. Sperm viability and motility in both fresh and thawed samples were similar in classes H and A, while significantly lower values were measured in class L. The relative decrease in sperm viability and motility after cryopreservation increased from class H to A to L. The lipid content of spermatozoa (micrograms per 10(9) cells) increased significantly after freezing and thawing in classes H and A but not in class L. This result indicated that active sperm lipid metabolism might be responsible for the increase in lipid content. Phospholipid and triacylglycerol contents increased whereas free cholesterol content decreased after thawing. The fatty acid composition of fresh spermatozoa was similar in all three classes. The proportion of polyunsaturated fatty acids decreased significantly after freezing and thawing, indicating contamination from the diluent or peroxidation. After freezing and thawing, superoxide dismutase activity in spermatozoa was significantly higher in class L than in classes H and A, which did not differ from each other.

1. The effect of food restriction on the quality of semen production and fertility in broiler breeder males was studied.2. Seventy-two Ross broiler breeder males, from 20 to 54 weeks of age, were divided into 4 groups and fed as follows: group 1 = 110 g/bird/d; group 2 = 120 g/ bird/d; group 3 = 130 g/bird/d; group 4 = ad libitum.3. Body weight, sperm quality (volume, concentration, % motility and % live cells) and fertility were measured. The birds were slaughtered at 55 weeks of age; the abdominal fat pad and testicles were weighed.4. Groups 2 and 3 produced the highest volume of semen. The quality of semen was very similar in all the restricted groups.5. Males fed ad libitum produced semen with the best motility and percentage of live cells. Groups 3 and 4 showed the best fertility percentage (79%) against group 1 and 2 (59 and 72% respectively).

Changes in the proportions of the various lipid components in spermatozoa were investigated throughout the reproductive period (24–72 wk of age) of male chickens. Sperm motility and in vivo fertility were also measured, and correlation coefficients with the lipid values were determined. The proportion of total phospholipid (PL) increased to reach a maximum value at 39 wk and decreased significantly thereafter. The relative content of free cholesterol and triacylglycerols showed no change in spermatozoa during aging or in relation to fertility values; free fatty acids and cholesterol esters increased continuously with age. Of the various PL classes, phosphatidylserine and phosphatidylcholine displayed a pattern of changes with age positively and negatively, respectively, in relation to the changes of fertility. The proportion of phosphatidylethanolamine had significantly decreased by the end of the reproductive period. The proportions of C16:0, C18:0, and C18:1 n-9 within the PL of the spermatozoa increased with age, and those of C20:4n-6, C22:4n-6, and C22: 6n-3 decreased. Positive correlations were found between fertility and total PLs, phosphatidylserine, and PL-bound C20:4n-6 and C22:4n-6; a negative correlation was found between fertility and phosphatidylcholine. Motility was positively correlated with the level of PL and negatively with that of free cholesterol; it was also positively correlated with the levels of C22:4n-6 and C22:6n-3 and negatively with those of C16:0, C18:0, and C18: ln-9. The results suggest that the lipid and fatty acid compositions of spermatozoa may be important predictors of fertility.

Summary.Egg-laying in hens exposed for more than 11 months to photostimulatory daylengths was intermittent and associated with a reduction in numbers of yellow-yolky ovarian follicles. Old laying hens (105 weeks) had lower concentrations of luteinizing hormone (LH) in the pituitary gland and plasma and reduced pituitary gland responsiveness to chicken LH-releasing-hormones (LHRH-I and II) in vivowhen compared with young laying hens (28 weeks). Four weeks after transfer from 14 to 8 h light/day, egg production almost stopped in old, but not in young hens, although plasma LH concentrations decreased in all birds. After transfer from 14 to 20 h light/day, plasma LH increased in young, but not in old, hens, without a change in the rate of egg production. Reproductive function was enhanced in old hens returned to long days after induction of a moult and ovarian regression by reducing daylength and dietary restriction. Moulted hens had a greater rate of egg production, higher concentrations of plasma LH and a greater pituitary-gland responsiveness to LHRH-II in vivothan unmoulted control hens. After transfer from 14 to 8 h light/day, egg-laying decreased more rapidly in unmoulted than in moulted hens; transfer to 17 h light/day increased egg production in moulted, but not in unmoulted, birds. Induction of ovarian regression in old hens by dietary restriction alone also enhanced reproductive function after the dietary restriction was relaxed. Egg-laying was more persistent in hens brought into lay for a second year by transferring them from 3 to 11 h light/day than in hens transferred from 3 to 20 h light/day. Egg production was stimulated in hens maintained on 3 or 11 h light/day for 42 weeks, after transfer to 20 h light/day. Egg production ceased in hens maintained on 20 h light/day for 46 weeks, after transfer to 3 h light/day.These observations are consistent with the view that poor persistence of laying in hens <2 years old and exposed continuously to long days is caused, in part, by a reduction in hypothalamic–gonadotroph function. This reduction in neuroendocrine function may be due, in part, to the development of relative photorefractoriness.Keywords:ovary; ageing; chicken; LH; egg-laying; seasonal breeding; photorefractoriness

The aim of this study was to investigate the effects of supplementing the diet of the male chicken with α-linolenic acid (18:3n-3) on the phospholipid fatty acid composition, motility and fertilizing ability of chicken spermatozoa. The birds in the control group received a diet supplemented with soybean oil rich in linoleic acid (18:2n-6) whereas those in the test group were supplemented with linseed oil rich in α-linolenic acid. A number of age-related changes in the lipid parameters of the spermatozoa were observed in control birds. Between 24 and 72 weeks of age the amount of total lipid in the spermatozoa of control birds increased by approximately 2.4 times and the proportions of cholesterol and free fatty acid also increased significantly, whereas the proportions of phospholipid and triacylglycerol decreased. In addition, the proportion of phosphatidylcholine in the total phospholipid increased, whereas the proportion of phosphatidylserine decreased during the same period. The proportion of docosatetraenoic acid (22:4n-6) in the phospholipid decreased significantly between 24 and 72 weeks of age. The concentration of spermatozoa in the semen of control birds increased to a maximum at week 39 and had decreased significantly by week 72. Supplementation with α-linolenic acid had little or no effect on the proportion of docosahexaenoic acid (22:6n-3) in the phospholipid profile of the spermatozoa. However, supplementation with α-linolenic acid did produce a significant but small increase in the proportion of docosapentaenoic acid (22:5n-3) recorded at 39 and 54 weeks. Thus, this study shows that the fatty acid composition of the sperm phospholipid demonstrates a marked resistance to dietary manipulation. Supplementation with α-linolenic acid significantly enhanced semen fertility at week 39. The results suggest that the small increase in the proportion of n-3 fatty acids in the sperm phospholipids induced by enriching the diet with α-linolenic acid is associated with a significant improvement in semen quality at 39 weeks of age.

Spermatozoa and seminal plasma from cockerels at the beginning and end of their reproductive periods were examined for their lipid composition and associated antioxidant capacities. The significant reduction in concentration of spermatozoa with age was associated with a large increase in lipid concentrations in spermatozoa and in seminal plasma. This change in lipid concentration was accompanied by increases in the proportions of phospholipid and free cholesterol; in constrast, the proportions of these lipid moieties in seminal plasma were reduced. The major phospholipid fractions in the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. There was a large decrease with age in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline in the spermatozoa and seminal plasma. These major changes in phospholipid content were accompanied by a decrease in the amount of phosphatidyl serine in the spermatozoa and increases in phosphatidyl inositol and cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by considerable reductions in the content of the major polyunsaturated fatty acids 20:4 (n-6) and 22:4 (n-6). The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase. The role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age are discussed.

The Milanino is an Italian chicken breed included in a conservation project run by the University of Milan. It is characterized by good fertility, heavy body weights, high adaptation ability to adverse climate conditions, and disease resistance. Because of these characteristics, the Milanino could represent an important genetic resource for alternative production systems. This research was aimed at studying the effect of bird density on growth and slaughter performance, as well as stress response in Milanino chickens kept in outdoor pens. One hundred and sixty Milanino chickens were randomly assigned to 2 experimental groups kept at different densities (2 m2/bird and 8 m2/bird) and were slaughtered at 185 days of age. Growth and slaughter performance and stress condition were recorded. The interaction bird density * sex * age significantly affected body weight and an opposite trend was found between females and males: heavier females were found in the high-density group, while heavier males were found in the low-density group. Bird density did not affect carcass weight data. The stress marker (H/L ratio) was significantly higher in birds kept at the higher density (2 m2/bird). In conclusion, the Milanino provided satisfactory growth performance with different rearing density but the lower density, 8 m2/bird, should be preferred to minimize welfare problems for male birds.

In Italy, ostrich breeding is a growing business, due to consumer demands for alternative meat, but little information is available on egg production. The purpose of this study was to describe productive and reproductive performance on an ostrich farm in northern Italy and to identify factors influencing egg and chick weight. Eggs were collected from five trios (one male per two females), incubated, and candled at 13, 26, and 38 d. Egg weight was recorded at collection, at set, and at each candling. Chicks were weighed at hatch. Fertility was 69.7%, whereas hatchability of egg set and of fertile eggs were 51.5 and 73.9%, respectively. Egg weight was 1,558 and 1,530 g at collection and at set, respectively, and the mean egg weight loss (14.2%) from set to 38 d was in the normal range for ostriches. There was a positive association between egg weight at collection and both egg weight during incubation and chick weight. Egg weight at set and at first candling decreased as storage time increased (–3.5 and –2.9 g/d, respectively). Eggs laid in March were heavier and had the greatest weight losses. Results show that the main source of variability for egg weight as well as fertility and hatchability was the trio rather than environmental conditions.