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Preen gland secretions were obtained from several hens that were rearing their chicks and the content of these secretions was analysed. From these results, a synthetic analogue of the secretions was created (given the title Mother Hen Uropygial Secretion Analogue, or MHUSA, in this study). According to a blinded, controlled experimental design, heavy broilers (strain SASSO T56N) were reared from 1 day of age in an environment treated with either MHUSA or control. At 80 days the birds were slaughtered. Post mortemcarcass weight, abdominal fat and fillet weights were then measured. Colour, pH and yield were also measured as indicators of meat quality. Broilers exposed to MHUSA had both higher carcass weights and higher fillet weights compared with control-treated birds (P < 0.05). Abdominal fat, pH, water loss and colorimetry results were similar between the treatment groups at all time points (24 h and 6 days post mortem) and also after a cooking procedure. The meat from the MHUSA birds was less yellow compared with control. It is concluded that constant exposure to MHUSA from rearing until slaughter improves growth rate in broilers without significantly affecting meat quality.
Nutrition modulates both production and composition of milk. Milk composition was studied in rats chronically fed a diet without additional lipids, and therefore eating only traces of the recommended supply of essential polyunsaturated fatty acid. Despite a large decrease in milk-protein synthesis, only protein composition, but not protein concentration, was found to change in the milk of rats following a lipid-deprived diet. Correlatively, we observed a substantial increase in the lactose concentration of milk. Analysis of milk proteins by two-dimensional electrophoresis demonstrated that the relative proportion of the various molecular forms of κ-casein, an O-glycosylated protein, was modified in the milk of rats receiving the lipid-deprived diet. In tissues, differences in the two-dimensional pattern of κ-casein between control and lipid-deprived rats were similar, if not identical. In contrast to κ-casein, the molecular forms of α-lactalbumin, an N-glycosylated protein, were not affected by the diet. These data provide evidence that O-glycosylation of milk proteins in the secretory pathway of mammary epithelial cells is modulated by the lipid content of experimental diets.
The present work was intended to analyse the chemical composition and oxidative stability of the muscle biceps femoris and adipose tissues from Iberian pigs fed different finishing diets: free-range feeding on grass and acorns in a ‘Montanera’ traditional system (MON), fed in confinement with a mixed diet containing high-oleic sunflower oil (115 g/kg of diet) and supplemented with 250 mg/kg α-tocopherol (HOVE), and fed in confinement with a tocopherol-non-supplemented control mixed diet (CON). Muscles from MON pigs contained significantly (P < 0.05) higher amounts of intramuscular fat than those from HOVE and CON pigs. Muscles from MON and HOVE pigs had significantly higher levels of α-tocopherol than muscles from CON pigs whereas free-range feeding provided significantly higher levels of γ-tocopherol to muscles from MON pigs than the experimental diets did to CON and HOVE pigs. Adipose tissues from MON and HOVE pigs contained significantly lower proportions of saturated fatty acids and significantly higher levels of oleic acid and monounsaturated fatty acids than those from CON pigs. Tissues from MON pigs contained significantly smaller levels of polyunsaturated fatty acids than those from CON and HOVE pigs. To a higher extent, feeding background affected the fatty acid composition of polar lipids from the muscle bicepsfemoris than that of neutral lipids. Tissues from MON pigs contained significantly smaller ω-6/ω-3 values than those from pigs fed mixed diets. Compared to tissues from CON pigs, those from MON and HOVE pigs exhibited a higher oxidative stability as a likely result of a most favourable fatty acid composition and the presence of higher tocopherol levels.
This experiment investigates the effects of maternal nutrient restriction in late gestation on the offsprings’ postnatal metabolism and performance. Forty purebred Shropshire twin lambs born to ewes fed either a high-nutrition diet (H) (according to standard) or a low-nutrition (L) diet (50% during the last 6 weeks of gestation) were studied from birth until 145 days of age. In each feeding group, two different sires were represented, ‘growth’ (G) and ‘meat’ (M), having different breeding indices for the lean : fat ratio. Post partum all ewes were fed the same diet. Lambs born to L-ewes had significantly lower birth weights and pre-weaning growth rates. This was especially pronounced in L-lambs born to the M-ram, which also had markedly lower pre-weaning glucose concentrations than the other three groups of lambs. L-lambs converted milk to live weight with an increased efficiency in week 3 of life. Their glucose concentrations and growth rates were both increased. Plasma glucose concentrations in LM-lambs became similar to those observed in H-lambs post-weaning. However, LM-lambs continued to be lighter than the other groups throughout the experimental period and were unable to compensate for the reduced weight at birth despite having the highest daily fractional growth rates. LG-lambs had the highest plasma glucose concentrations of all four groups of lambs, and they indeed reached body weights comparable to those of the H-lambs by 145 days of age. The increased growth rate post-weaning in L-lambs was not reflected in fat deposition, as L-lambs had lower fat deposition than H-lambs. This may relate to the lower plasma insulin levels found in the L-lambs than in the H-lambs. In conclusion, a 50% reduction of maternal nutrient supply in the last 6 weeks of gestation reduces the birth weight and pre-weaning growth of the offspring due to lower milk intake. Growth rates can be restored when an adequate post-weaning diet is provided, but the prenatal nutrition may programme postnatal metabolism differentially depending on genotype, thus affecting the ability of the ad libitum-fed lamb to achieve a given body weight by a certain age.
Various strategies have been developed to increase the cellular level of (n-3) polyunsaturated fatty acids in animals and humans. In the present study, we investigated the effect of dietary myristic acid, which represents 9% to 12% of fatty acids in milk fat, on the storage of α-linolenic acid and its conversion to highly unsaturated (n-3) fatty acid derivatives. Five isocaloric diets were designed, containing equal amounts of α-linolenic acid (1.3% of dietary fatty acids, i.e. 0.3% of dietary energy) and linoleic acid (7.0% of fatty acids, i.e. 1.5% of energy). Myristic acid was supplied from traces to high levels (0%, 5%, 10%, 20% and 30% of fatty acids, i.e. 0% to 6.6% of energy). To keep the intake of total fat and other saturated fatty acids constant, substitution was made with decreasing levels of oleic acid (76.1% to 35.5% of fatty acids, i.e. 16.7% to 7.8% of energy) that is considered to be neutral in lipid metabolism. After 8 weeks, results on physiological parameters showed that total cholesterol and low-density lipoprotein-cholesterol did not differ in the diets containing 0%, 5% and 10% myristic acid, but were significantly higher in the diet containing 30% myristic acid. In all the tissues, a significant increasing effect of the substitution of oleic acid for myristic acid was shown on the level of both α-linolenic and linoleic acids. Compared with the rats fed the diet containing no myristic acid, docosahexaenoic acid significantly increased in the brain and red blood cells of the rats fed the diet with 30% myristic acid and in the plasma of the rats fed the diet with 20% myristic acid. Arachidonic acid also increased in the brain of the rats fed the diet with 30% myristic acid. By measuring Δ6-desaturase activity, we found a significant increase in the liver of the rats fed the diet containing 10% of myristic acid but no effect at higher levels of myristic acid. These results suggest that an increase in dietary myristic acid may contribute in increasing significantly the tissue storage of α-linolenic acid and the overall bioavailability of (n-3) polyunsaturated fatty acids in the brain, red blood cells and plasma, and that mechanisms other than the single Δ6-desaturase activity are involved in this effect.
Neonatal lamb mortality represents both a welfare issue (due to the considerable suffering and distress) and an important production inefficiency. In lambs, approximately 80% of mortality can be attributed to the starvation–mismothering–exposure complex and occurs in the first 3 days after birth. It was the object of this review to determine the micronutrient(s) most likely to have a positive effect on neonatal lamb survival when included above the requirement for that micronutrient. Micronutrients discussed were Co, Cu, I, Fe, Mn, Se, Zn, vitamins A and E and n-3 fatty acids. For Co, Fe, Mn and Zn, there was no evidence of positive responses to supplementation. Cu and I had toxicity thresholds that were sufficiently close to requirement that supplementing above requirement presented a risk of inducing toxicity. In the case of vitamin A, while serum concentrations indicated that sub-optimal status did exist, long-term buffering from liver stores (from grazing) makes experimentation difficult and practical benefits to supplementation unlikely. Therefore, the most likely candidates for supplementation were Se, vitamin E and fatty acids. Fatty acid supplementation with fish oils or docosahexaenoic acid-containing algal biomass consistently improved lamb vigour but it is unlikely that supplementation will be economic. Positive responses to Se supplementation throughout gestation were recorded. However, in many studies the Se status of control ewes was marginal and there is a need for more studies where control ewes are clearly adequate in Se. Positive responses to vitamin E supplementation above requirement in the last-third of gestation were observed but the optimum dietary inclusion of vitamin E and period of feeding during pregnancy still require clarification.
The effect of acute exercise was studied in a group of 42 clinically healthy young Standardbred trotters. These trotters had been divided into four groups according to their age. Their ages were from 1.5 to 3 years. Three jugular venous blood samples were collected via venipuncture from each horse. These samples were collected while (1) at rest, (2) after the end of the exercise and (3) 30 min after the end of the exercise. Exercise showed a significant increase in plasma leptin concentration (3.8 ± 0.31 at rest v. 4.3 ± 0.37 just after exercise and 4.4 ± 0.47 ng/ml after a 30-min rest; ANOVA P < 0.05). The difference between values obtained 30 min after exercise and at rest was significantly greater in 1.5-year-old horses than in those aged 2.5 years (+1.3 ± 0.43 v. +0.1 ± 0.15 ng/ml; ANOVA P < 0.05). The mean plasma leptin concentration was higher in fillies than in colts (4.9 ± 0.47 v. 3.5 ± 0.36 ng/ml; ANOVA P < 0.05). A positive correlation between the plasma concentrations of leptin and triacylglycerides measured just after exercise was detected (r = 0.65). The acute exercise significantly increased the plasma concentration of ghrelin that was measured just after exercise (1255 ± 55.9 v. 1127 ± 54.2 pg/ml; ANOVA P < 0.05). The exercise-induced age-related changes in the plasma ghrelin concentration were significantly lower in 2.5-year-old trotters than in 1.5-year olds. To sum up, the changes in plasma leptin and ghrelin concentrations during bouts of exertion tend to decrease with age and/or training of Standardbred foals.
Milk yield is reduced by pregnancy, and the present experiment was conducted to study the biological basis for the negative effect of pregnancy on milk yield. A total of 16 dairy cows were fed at either a normal or a low feeding level (eight cows per treatment), and half of them were inseminated after approximately 3 months of lactation and the other half were not inseminated. Mammary biopsies were taken at approximately 9 months of lactation. The milk yield of pregnant cows was reduced by 2.6 kg/day, and lactation persistency was reduced already from the time of insemination. Low feeding level reduced the milk yield by 9.8 kg/day from week 8 to week 39 of lactation, whereas no interaction between pregnancy and feeding level was found. Cell proliferation (Ki-67) and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling, TUNEL) were unaffected by feeding level, and pregnancy tended to reduce cell proliferation but had no effect on apoptosis. Reduced cell proliferation may explain the reduced lactation persistency in pregnant cows. Transcription of oestrogen receptor α, progesterone receptor A and B, and long and short isoforms of the prolactin receptor were higher in pregnant cows compared with non-pregnant cows. Feeding level did not mediate changes in transcription of genes. Transcription of other cell-turnover-related genes (IGF-I, IGF binding protein-5, caspase-3) as well as genes related to the secretory activity of the cells (α-lactalbumin and acetyl CoA carboxylase α) was not affected by pregnancy or by feeding level.
In the first experiment, osmotic pressure of semen and seminal plasma in a semen sample from each of the 20 mature Nili-Ravi buffalo bulls was determined. In the second experiment, effects of osmotic pressure on motility (%), plasma membrane integrity (%) and viability (%) in fresh and frozen-thawed semen samples from each of the seven mature Nili-Ravi buffalo bulls was determined. In the first experiment, seminal plasma was harvested by centrifuging semen at 400 × g for 10 min at 37°C and osmotic pressure was determined using an osmometer. In the second experiment, motility (%) was assessed in fresh and frozen-thawed (37°C for 30 s) semen samples using a phase-contrast microscope (×400). Plasma membrane integrity (%) was determined by mixing 50 μl each of fresh and frozen-thawed semen with 500 μl of solution having an osmotic pressure of 50, 100, 150, 190 or 250 mOsm/l (hypotonic treatments of fructose + sodium citrate) and incubating at 37°C for 1 h. Viability (%) of fresh and frozen-thawed spermatozoa before and after challenging them to osmotic pressure (hypotonic treatments) was assessed using supravital stain under a phase-contrast microscope (×400). In the first experiment, the mean ± s.e. osmotic pressures of the buffalo semen and seminal plasma were 268.8 ± 1.17 and 256.0 ± 1.53 mOsm/l, respectively. In the second experiment, motility (%) decreased (P < 0.05) in frozen-thawed semen samples as compared with fresh semen (60.1 ± 1.34 v. 81 ± 1.57, respectively). The plasma membrane integrity (%) and magnitude of osmotic stress in fresh and frozen-thawed semen samples was higher (P < 0.05) at 50, 100, 150 and 190 mOsm/l as compared with 250 mOsm/l. Loss of viability (%) in fresh and frozen-thawed semen samples was higher (P < 0.05) at 50 mOsm/l (59% in fresh, 70% frozen thawed) as compared with other osmotic pressures, while it was lowest at 250 mOsm/l (4.1% for fresh, 9.7% frozen thawed). In conclusion, osmotic pressure of Nili-Ravi buffalo semen and seminal plasma is determined. Furthermore, variation in osmotic pressure below 250 mOsm/l is not favorable to fresh and frozen-thawed buffalo spermatozoa.
The ability of young rabbits to digest a solid diet was evaluated according to the weaning age: 21 (W21, 12 litters) or 35 (W35, 12 litters) days of age. From 14 days onwards, the rabbits were fed the same pelleted feed. Three methods were compared to estimate the faecal digestibility in the young rabbits, between 24 to 28 and 38 to 42 days. Digestive balance at ileal and faecal levels was determined for the main nutrients provided by milk and solid feed. The W21 rabbits increased their solid feed intake only 2 days after their weaning, when compared with suckling rabbits. Thus, their crude protein (CP) intake remained lower until 26 days compared with the W35 rabbits (from 41%, P < 0.01), as well as their crude fat intake until 28 days (from 72%, P < 0.001). On the contrary, the W35 rabbits increased their solid feed intake without a delay after weaning, quickly reaching the intake level of the W21 rabbits. The amounts of organic matter (OM) and CP reaching the caecum were increased on day 28 by 56% and 42% in the W21 rabbits compared with the W35 rabbits, respectively (P < 0.05), and were similar between groups on day 42. Starch ileal digestibility coefficients were 94·2% and 95·4% in 28- and 42-day-old rabbits, respectively, irrespective of the weaning age. The amount of starch flowing through the ileo-caecal junction was low and only tended to be higher on day 28 in the W21 group (0.20 v. 0.15 g/day in the W35 group, P = 0.10). The digestive balance pointed out that the digestible energy intake was similar between weaned and suckling rabbits from 23 to 27 days, a phenomenon partly explained by a high ability of the W21 rabbits to digest starch (98%) and NDF (36%). Indeed, the amounts of starch and NDF digested by the W21 group were 2.0- and 2.4-fold higher than those of the W35 rabbits at this period (P < 0.001). However, they ate 20% less digestible proteins than still-suckling rabbits (P < 0.001). From 38 till 42 days, only a lower ability of the W21 rabbits to digest lipids was detected (P < 0.05). In conclusion, early-weaned rabbits were able to adapt quickly to digest large amounts of starch and fibres.
Although endogenous synthesis of conjugated linoleic acid (CLA) in the mammary gland of lactating cows has been already well documented, no study has determined so far as to which tissue and/or organ is involved in CLA synthesis in the growing ruminant except one study showing that CLA synthesis does not occur in ruminant liver. In this context, adipose tissue appears to be a good candidate for endogenous synthesis of CLA in the growing ruminant. The aim of this study was to compare the respective metabolisms of 11trans 18:1 (vaccenic acid, VA) and 9cis,11trans 18:2 (rumenic acid) to that of stearic acid (the preferential substrate of Δ9 desaturase) in adipose tissues (subcutaneous, SC and intermuscular, IM) of six Charolais steers by using the in vitromethod of incubated tissue slices. Samples of SC and IM adipose tissues were incubated at 37°C for 16 h under an atmosphere of 95% O2/5% CO2 in a medium supplemented with 0.75 mM of fatty acid (FA) mixture (representative of circulating non-esterified FA) and 186 μM [1-14C]-18:0 or 58.6 μM [1-14C]-VA or 56 μM [1-14C]-9cis,11trans CLA. Viability of explants was verified by measuring metabolic functions (glucose uptake and glucose-6-phosphate dehydrogenase activity). After 16 h of incubation, FA uptake was similar for all FA (18:0, VA and 9cis,11trans 18:2) in both SC and IM adipose tissues (around 40%). Once in adipose tissue, all FA were preferentially esterified (>80% of cell FA) favouring neutral lipid synthesis (around 90% of esterified FA). Stearic acid was highly (27%) desaturated into oleic acid in SC adipose tissue whereas this desaturation was much lower (6.8%) in IM adipose tissue (P < 0.0001). VA was desaturated into 9cis,11trans CLA at a low extent of about 2.5% to 4.4% in both adipose tissues probably because of a limited affinity of Δ9 desaturase for VA. 9cis,11trans CLA was itself converted by desaturation into 6cis, 9cis,11trans 18:3 at the intensity of 10.8% and 14.5% of cell 9cis,11trans CLA in SC and IM adipose tissues, respectively. In conclusion, bovine adipose tissues of the growing ruminant were especially involved in the endogenous synthesis of CLA from VA and in its desaturation into conjugated derivative, mainly 6cis, 9cis,11trans 18:3, of which biological properties need to be elucidated.
Seasonal effects on luteal activity during post partum were evaluated in two consecutive studies in 253 dairy cows in Northern Italy. In study 1, plasma progesterone concentrations were determined on days 14, 21, 28, 35, 42, 49 and 56 post partum and in study 2 cows were synchronized and inseminated at a fixed time using two regimes based on the ‘Ovsynch’ protocol. Study 1: Animals were classified as luteal (progesterone >1.5 ng/ml in at least two consecutive samples) or non-luteal (progesterone <1.5 ng/ml in all samples). The proportion of cows without luteal activity from calving to day 56 post partum was 47/253 (18.5%). Of the 47 cows without luteal activity, 42 (89%) were detected during the warm months of the year and five were detected during the cold months of the year, and the effect of season was highly significant (P < 0.001). Study 2: Three study groups were established; control (CONT, untreated cows, n = 92), GPG (cows receiving gonadotropin-releasing hormone (GnRH) on day 0, PGF2α on day 7 followed by a second dose of GnRH 24 h later, n = 80); and HPH (the same as the GPG group, but with human chorionic gonadotropin (hCG) substituted for GnRH, n = 81). In the GPG and HPH groups, cows were inseminated 16 to 22 h after the second GnRH or hCG injection. Untreated cows were inseminated at first estrus after a voluntary weaning period. Because the effects of the GPG and HPH regimes on pregnancy rate were not significantly different, data were pooled into a single treatment group (TREAT). Pregnancy rates during the warm months of the year were 16% and 15% at first service and 65% and 66% at day 135 post partum for CONT and TREAT groups, respectively. Pregnancy rates during the cold months of the year were 36% and 38% at first service and 72% and 76% at day 135 post partum for CONT and TREAT groups, respectively. There was an effect of season (P < 0.05) but not of treatment on pregnancy rate. Treatment reduced the number of days from calving to conception during both the cold (101 ± 3.2 v. 121 ± 3.1 days; P < 0.001) and warm seasons (122 ± 3.2 v. 145 ± 3.1 days; P < 0.001). In conclusion, the present study shows that (i) heat stress during the warm season can compromise luteal activity and (ii) that regimes based on the Ovsynch protocol did not improve pregnancy rate at first service or by 135 post partum, but they had a positive effect on the calving-to-conception interval.
With the aim of carrying out chimaerism and somatic cell–midblastula transition (MBT) embryos co-culture experiments in freshwater fish species, we evaluated the effect of osmolarity and composition of two media commonly used in cell fish culture on MBT zebrafish embryos and their further development and survival. To this end, wild zebrafish dechorionated embryos in midblastula stage were cultured for 6 days (Experiment 1: 189 embryos) or 1 h (Experiment 2: 150 embryos) in three different media: Hanks’ 10% (H-10), 35 mOsm; Hanks’ 100% (CH), 315 mOsm; and L-15 with serum (L-15: 315 mOsm). High osmolarity affected the survival rate (6 days: L-15: 45.1% v. CH: 72.34% v. H-10: 100%, P < 0.05; after 6 days: 0% both in L-15 and CH) and slowed their developmental timing. Embryos showed tail deformation (curly) as well as body paralysis at 48 h when they showed tail movements at 28 h. Differences in tail deformation were observed between high-osmolarity groups (CH: 85.10% v. L-15: 98.04%; P < 0.05). In Experiment 2, no effects on survival rate were observed. Teratogenic effects were only observed in L-15 (L-15: 12.98% v. CH: 0%; P< 0.05). Loss of motility was not detected in any group at 48 h. Optimum osmolar condition for cultured cells and also embryonic cells is around 315 mOsm and so, during chimaerism experiments (usually practised at MBT stage), present results indicate that midblastula embryos can acceptably bear the effects caused by 315 mOsm (CH) for 1 h, even though this involves a certain delay in developmental timing.
Histological intestinal villus alterations were studied in piglets fed a raw pigeon pea meal (PM) diet including a powder mixture of amorphous charcoal carbon and wood vinegar compound solution (CWVC). Twenty-eight male castrated piglets were divided into seven dietary groups of four piglets each. The control group was fed raw PM supplemented to the basal diet (178 g/kg crude protein, 4.23 kcal/g gross energy) at 0 g/kg (CONT), 200 g/kg (PM200) and 400 g/kg (PM400). The treatment groups were fed CWVC in both PM200 and PM400 diet groups at levels of 10 g/kg and 30 g/kg (PM200 + CWVC10, PM200 + CWVC30, PM400 + CWVC10 and PM400 + CWVC30). With increasing dietary PM levels, daily feed intake tended to increase. In contrast, daily body-weight gain tended to decrease, significantly in the PM400 group (P < 0.05), resulting in a significant decrease of feed efficiency in PM groups (P < 0.05). Body-weight gain and feed efficiency were higher in the CWVC groups compared with the PM groups. The duodenum and ileum were longer (P < 0.05) in the PM400 group than in CONT, but were similar to CONT in CWVC groups. The liver was heavier (P < 0.05), whereas the weights of the heart, kidney and stomach were decreased in the CWVC groups than in other groups. Most values for the intestinal villus height, cell area and cell mitosis number were lower in PM groups than those in CONT (P < 0.05) for each intestinal segment; however, these values were higher in CWVC groups than in PM groups (P < 0.05). The epithelial cells on the duodenal villus surface of the PM200 group showed cell morphology almost similar to CONT. However, the PM400 group had a smooth villus surface due to the presence of flat cells. The epithelial cells of the CWVC groups were protuberated, resulting in a much rougher surface than CONT. The current growth performance and histological intestinal alterations in piglets fed PM and PM + CWVC diets demonstrate that the intestinal features might be atrophied by feeding PM, resulting in decreased growth performance. CWVC might prevent the harmful effects of PM dietary toxins on intestinal function, resulting in a normal growth performance.
Milk protein genes are among the most intensively expressed and they are active only in epithelial mammary cells of lactating animals. They code for proteins which represent 30% of the proteins consumed by humans in developed countries. Mammary gland development occurs essentially during each pregnancy. This offers experimenters attractive models to study the expression mechanisms of genes controlled by known hormones and factors (prolactin, glucocorticoids, progesterone, insulin-like growth factor-1 and others) as well as extracellular matrix. In the mid-1970s, it became possible to identify and quantify mRNAs from higher living organisms using translation in reticulocyte lysate. A few years later, the use of radioactive cDNAs as probes made it possible for the quantification of mRNA in various physiological situations using hybridisation in the liquid phase. Gene cloning offered additional tools to measure milk protein mRNAs and also to identify transcription factors. Gene transfer in cultured mammary cells and in animals contributed greatly to these studies. It is now well established that most if not all genes of higher eukaryotes are under the control of multiple distal regulatory elements and that local modifications of the chromatin structure play an essential role in the mechanisms of differentiation from embryos to adults. The technique, known as ChIP (chromatin immunoprecipitation), is being implemented to identify the factors that modify chromatin structure at the milk protein gene level during embryo development, mammogenesis and lactogenesis, including the action of hormones and extracellular matrix. Transgenesis is not just a tool to study gene regulation and function, it is also currently used for various biotechnological applications including the preparation of pharmaceutical proteins in milk. This implies the design of efficient vectors capable of directing the secretion of recombinant proteins in milk at a high concentration. Milk protein gene promoters and long genomic-DNA fragments containing essentially all the regulatory elements of milk protein genes are used to optimise recombinant protein production in milk.
A large number of environmental factors affect the daily milk production of a cow. Lactation curves included in the French test-day model are modelled as a function of days in milk with semi-parametric curves (splines). The proper modelling of environmental effects in the test-day analysis was investigated using test-day records collected from the first three lactations of French Montbéliarde cows from 1988 to 2005. Four lactation-curve effects describing calving month, length of dry period, age at calving and gestation defined within parity-class were fitted. The shape of lactation curves did not depend on year of calving, which can be modelled as a constant over the whole lactation. To reduce computational requirements and time, data were pre-adjusted in a first step for fixed effects with no year interaction, and then used for genetic evaluation. Correlations for each lactation between 305-day estimates of genetic and permanent environment effects computed using pre-adjustment factors obtained at a 4-year interval were virtually one. The use of a two-step procedure had a very limited impact on the estimates of genetic and permanent environment effects. The minimum correlations with values estimated with a one-step procedure were 0.9984 and 0.9974, respectively. The knowledge of systematic environmental effects affecting the cow daily yield through lactation curves offers interesting perspectives to predict future daily milk production.
In the Molise region (Italy), some autochthonous populations are still bred and, between them, some wild horses named ‘Pentro horses.’ The breeding area is a natural pasture. It is 2200 ha extended including a broad plane surrounded by wooden hills. The aim of this research was to determine the nutritional characteristics of this area over a 2-year period to improve the management of the herd and to define the stocking rate in relation to the forage production in terms of production and quality. The forage samples were collected over two successive years during the grazing period (May to October) from five experimental areas and analysed for dry matter (DM), organic matter (OM), crude protein (CP), crude fibre (CF), neutral-detergent fibre (NDF), acid-detergent fibre (ADF), acid-detergent lignin (ADL) and gross energy (GE). Horse feed units (HFU) and horse-digestible crude protein (HDCP) were also predicted. Data were analysed with a one-way ANOVA test using month and area as factors. The DM, HFU and HDCP total production was determined to be compared with the total nutrient requirements of the herds from May to October. The results show that seasonal and yearly climatic variations significantly affect chemical composition and nutritive value of the pasture. The parameters most influenced were DM, CP, ADF and to a less extent NDF, while OM, ADL and GE show smaller differences during the observed period. The results show a low production per ha; nevertheless, because of the low stocking rate (0.3 to 0.6 head per ha), nutrient production meets the nutrient requirements of the horses regarding DM and energy. The differences among the areas have to be ascribed to the different botanical compositions and to the different draining capacity of the soil, and also in this case the greatest variations are for DM, CP and ADF.
In the rumen, plant particles are colonised and degraded by the rumen micro-organisms. Although numerous important findings about fibre-associated bacterial community were obtained using traditional or molecular techniques, little information is available on the dynamics of bacteria associated with feed particles during incubation in the rumen. In the present study, ryegrass leaf, ryegrass stem and rice straw, representing different carbohydrate compositions, were used as substrates and placed in the rumen of goats by using nylon bags, and PCR/DGGE (denaturing gradient gel electrophoresis) with subsequent sequence analysis were used to monitor the dynamics of and identify bacteria associated with the substrates during 24 h of incubation. DGGE results showed that substrate samples collected from 10 min to 6 h had similar DGGE patterns, with up to 24 predominant bands to each sample, including 14 common bands to all samples, suggesting a rapid and stable colonisation by a highly diverse bacterial community. Substrate samples collected at 12 and 24 h showed similar DGGE patterns but had great difference in DGGE patterns from those collected at 10 min to 6 h, suggesting an apparent shift in bacterial community. Sequence analysis indicated that most substrate-associated bacteria were closely related to fibrolytic bacteria. In conclusion, a highly diverse and similar rumen bacterial community could immediately colonise to different substrates and remained stable during the initial 6 h of incubation, but experienced a marked change after 12 h of incubation. Italian ryegrass leaf, Italian ryegrass stem and rice straw were colonised with a similar bacterial community.
In farm animals, salivary cortisol has become a widely used parameter for measuring stress responses. However, only few studies have dealt with basal levels of concentration of cortisol in pigs and its circadian rhythm. The aim of this study was to examine the effects of ambient temperature and thermoregulatory behaviour on the circadian rhythm of salivary cortisol levels in fattening pigs. Subjects were 30 fattening pigs of different weight (60 to 100 kg), kept in six groups in an uninsulated building in pens with partly slatted floors. Saliva samples were taken every 2 h over periods of 24 h at different ambient temperatures at two times in winter and four times in summer. Thermoregulatory behaviour was recorded in the same 24-h time periods. The effect of time of day, body weight, ambient temperature and behaviour on the cortisol level was analysed using a mixed-effects model. Two peaks of cortisol levels per day were found. This circadian pattern became more pronounced with increasing weight and on days where thermoregulatory behaviour was shown. Mean cortisol levels per day were affected by weight but not by thermoregulatory behaviour. From our data, we conclude that long-term variations in cortisol concentration may be influenced by increasing age and weight more than by the respective experimental situation. In assessing animal welfare, it seems more reliable to consider the circadian pattern of cortisol concentration instead of only one value per day.
Alfalfa protein is poorly utilised by ruminants due to its rapid degradation in rumen. The objective of the study was to assess the influence of spraying tannic acid (TA) on chopped alfalfa hay on in vitro rumen fermentation and nitrogen (N) retention by sheep. Alfalfa hay with and without TA was fed to sheep to determine nutrient digestibility and N balance. TA was sprayed on chopped alfalfa at three concentrations to determine its effect on in vitro fermentation of dry matter (DM) and N balance in sheep. Final TA concentrations were 0, 30, 60 and 90 g TA per kg DM. The control was sprayed with the same amount of water but without TA. In vitro DM degradation and the production of gas, ammonium-N (NH4-N) and short-chain fatty acid (SCFA) were measured. TA-sprayed alfalfa and the control were fed to sheep to determine nutrient digestibility and N retention. Addition of TA had no influence on the extent and rate of gas production but significantly decreased NH4-N concentration at 30 (P < 0.05), 60 and 90 (P < 0.0001) g/kg DM. Addition of polyethylene glycol (PEG) to TA-sprayed alfalfa increased NH4-N to a level comparable to non-TA-sprayed alfalfa. Spraying of alfalfa with TA significantly decreased (P < 0.05) isovalerate but did not affect the total and individual SCFA acid production. Tannic acid significantly (P < 0.05) reduced in vitro true degradability of DM (IVTD) after 24 h incubation at levels of 60 and 90 g TA per kg DM. Neutral-detergent fibre digestibility (dNDF) after 24 h (P < 0.01), 60 and 90 (P < 0.0001) g TA per kg DM. The effect of TA on either IVTD or dNDF was not significant (P > 0.05) after 48 h of incubation. There was a strong linear relationship between percentage increase in gas production due to PEG and protein precipitation capacity (R2 = 0.94). N digestibility was significantly reduced with all three levels of TA additions. However, the proportion of urine-N to total N output was reduced by adding 60 g (P < 0.05) and 90 g (P < 0.01) TA per kg DM. Serum metabolites and liver enzymes were not affected by TA (P > 0.05). Higher faecal N as the TA level increased indicates incomplete dissociation of tannin–protein complexes post ruminally. Factors affecting dissociation of tannin–protein complexes need further study.