Effect of restricted feeding and realimentation periods on compensatory growth performance and physiological characteristics of pigs

An experiment with 94 growing pigs was conducted to determine the effect of a feed restriction of 25% on performance, carcass quality, organ weight, blood hormone levels and some biochemical parameters. The experiment consisted of four periods of 21 days each. In the different periods animals (initial BW about 31 kg) were fed ad libitum (A) or restrictively (R), resulting at day 84 in Groups AAAA, AARA, RAAA and RARA. During Period I, the daily gain of restrictively fed pigs (Group R) was about 22% lower than from Group A (p < 0.01). During realimentation, compensatory growth was observed in Period II for Group RA, and in Period IV for Group RARA. No compensatory growth was observed for Group AARA, which was fed restrictively in Period III only (day 43 to 63). For the whole experiment (day 1 to 84), BW gain and feed conversion amounted to 830 g/d and 3.03 kg/kg, 798 g/d and 2.99 kg/kg, 813 g/d and 2.86 kg/kg, and 800 g/d and 2.78 kg/kg for Groups AAAA, AARA, RAAA and RARA, respectively. The decrease of liver and kidney weights as a result of restricted feeding was not significant and after three weeks of realimentation these differences almost disappeared. At day 3 after realimentation of restrictively fed pigs (Group RA) the growth hormone level was significantly increased, but at day 14 of realimentation this level turned out to be lower (p < 0.01) than in pigs fed ad libitum (Group AA). This was considered as a further indication of compensatory growth.     

Content and deposition of major mineral elements in different tissues and empty body of growing bulls of the german simmental breed

54 bulls of the German Simmental breed were fed either on a high energy level (maize silage ad libitum and 1.8 kg concentrate) or on a low energy level (maize silage restrictively and 1.0 kg concentrate). In dependence on feeding intensity a mean daily weight gain of 870 or 1210 g was obtained. Animals were slaughtered with a live mass of 200 kg, 350 kg, 500 kg, 575 kg and 650 kg. Empty body was divided into 13 cuts and afterwards separated into lean, bone and adipose tissues and tendons. Major mineral element content was determined in these tissues as well as in the noncarcass parts.

In the lean tissue the mean content (200 kg) of 0.3 g calcium, 10 g phosphorus, 1 g magnesium, 2.3 g sodium and 14.8 g potassium/kg dry matter decreased slightly with rising live mass (200–650 kg). The contents of major mineral elements were much higher in bone tissue. For the fattening period from 200 to 650 kg of live mass mean contents of 151.5 g calcium, 71.3 g phosphorus, 3.2 g magnesium, 5.1 g sodium and 1.1 g potassium per kg DM were analysed. Mineral element content of bone tissue increased with rising live mass as well as animals on low feeding intensity showed a higher mineral content than on high energy level. In all, major mineral element content in fat tissue was very low. In noncarcass parts head and legs calcium and phosphorus had analogous to bone tissue the highest concentration. Hide showed a high content of sodium, whereas organs and digestive tract had a high content of potassium and phosphorus. Total mass of major mineral elements in the different tissues increased above all in the fattening period of 200 to 350 kg. In carcass as well as in empty body, mass of calcium and phosphorus was much higher than magnesium, sodium and potassium. Also animals on low feeding intensity showed a higher mass of major mineral elements in carcass and empty body than animals on high energy feeding intensity. The intensively fed bulls had a mean deposition of 12.7 g calcium, 6.9 g phosphorus, 0.37 g magnesium, 1.2 g sodium and 2.1 potassium per 1000 g of empty body weight gain, whereas restrictively fed bulls deposited in average 15.0 g calcium, 7.8 g phosphorus, 0.4 g magnesium, 1.2 g sodium and 2.4 g potassium per 1000 g of empty body weight gain.     

Effect of compensatory growth on performance, carcass composition and plasma IGF-1 in grower finisher pigs

A total of 48 female pigs (Large White × Landrace × Duroc cross) were used to determine whether a compensatory feed regime influenced performance, carcass composition and the level of plasma IGF-1. Pigs of initial age 73 days were fed a commercial diet at 0.70 of ad libitum (R) for 40 days followed by a return to ad libitum feeding for a further 42 days. The control group was fed ad libitum (A) throughout. Groups of animals on R and A feed regimes were slaughtered at the end of restriction period (SL1), 2 days after refeeding ad libitum (SL2) to establish the more immediate effects of refeeding on IGF levels, and after 42 days refeeding (SL3; n = 8 for each group). As expected, during the restriction period, average daily live weight gain in all the slaughter groups of R pigs was significantly lower than A pigs (P < 0.01); there was no significant difference in feed conversion ratios. In the re-alimentation period of SL3, R pigs grew 12.9% faster (P = 0.033), indicating compensatory growth. At SL1, there was a trend for carcass weight (P = 0.108) of A pigs to be higher than R pigs, but at SL2 live weight and carcass weight of A pigs were significantly heavier than R pigs (P < 0.05), but not at SL3. For killing-out percentage, there was no difference in SL1. After refeeding for 2 days (SL2) and 42 days (SL3), R pigs had significantly lower killing-out percentage than A pigs (P < 0.05). As a proportion of live weight, R pigs had smaller heart, kidney and liver (P < 0.05) than A pigs at SL1. At SL2, only the kidney was smaller in the restricted group (P < 0.05) and there were no significant differences in SL3. As a proportion of carcass weight, Longissimus dorsi was heavier in the R pigs at SL1 (P = 0.108) and SL2 (P < 0.05), but not at SL3. At SL1, there was a trend for intramuscular fat of A pigs to be higher than R pigs. The plasma IGF-1 level was lower in R pigs than A pigs (P = 0.010) at SL1, and slightly lower at SL2 (P = 0.110), with no significant differences at SL3. Dietary restriction period influenced plasma IGF-1 levels, which returned to the ad libitum group levels when animals were refed, as did live weight and carcass weight. It appears that the internal organs and possibly fat, but not muscles, underwent a compensatory response when animals were refed.     

Effects of photoperiod and food availability on growth, leptin, sexual maturation and maintenance in the Mongolian gerbils (Meriones unguiculatus)

Reproductive activity of Mongolian gerbils is regulated by photoperiod nevertheless body weight regulation is controlled without ambient photoperiod. Food intake is a major factor affecting rodent reproductive efficiency. Leptin is a hormone secreted by adipose tissue and modulates food intake, energy expenditure and body fat stores. In this study we studied the interaction of photoperiod and food availability on growth, sexual maturation and leptin concentration in the male and female gerbils. Gerbils were gestated and reared in either 14L:10D or 2L:22D. At weaning, gerbils were housed individually and divided into three groups: fed ad libitum, fed 80% of ad libitum or fed 60% of ad libitum. Body weights were recorded at weaning and every week thereafter. After twelve weeks of treatment, animals were sacrificed and testes and uterine weights were determined and blood was collected for leptin measurement. Food restriction reduced body weight and inhibited reproductive development. Absolute paired testis weights were similar in ad lib and 80% of ad lib groups but significantly different compared with the 60% of ad lib group in both photoperiods. Body weights were also directly dependent upon the level of food restriction. Uterine mass was only affected in the 60% of ad lib group in 14L but both food restriction levels significantly affected the uterine weights in 2L. Significant variations were found in leptin profiles. Leptin concentration was highest in ad lib and 80% of ad lib groups and lowest in 60% of ad lib groups. These results suggest that the reproductive activity of Mongolian gerbils is sensitive to food intake and multiple potential environmental cues (e.g., food availability, temperature) can be utilized.     

Influence of the inflammatory status of entire male pigs on their pubertal development and fat androstenone

Androstenone production increases during pubertal development and plays a major role in boar taint. The objective of the present study was to evaluate the effect of a subclinical inflammation on the pubertal development of boars and hence on fat androstenone. Contrasted hygiene conditions were applied during rearing to increase the variability of the inflammatory status. Boars from a commercial cross line were allocated at 139±0.9 days of age (Day 0) and 81.3±5.9 kg of live weight either to Good (n=61) or Poor (n=54) hygiene conditions until slaughter at 172.9±4.8 days of age and 116.7±4.5 kg live weight. Inflammatory status, growth and pubertal development were evaluated on Day 0, Day 27 and at slaughter by analysing the blood formula, plasma inflammatory proteins; testosterone and oestradiol, salivary cortisol, rectal temperature, live weight, back fat thickness, weight of reproductive organs and clinical scores of organs (lungs, stomach, snout). Fat was collected on Day 27 by biopsy and at slaughter to measure androstenone concentration. A principal component analysis including inflammatory indicators followed by a clustering procedure was performed to identify pigs with a high (Infl+, n=50) or a low (Infl−, n=65) inflammatory status. Infl+ pigs had more granulocytes/ml, higher concentrations of haptoglobin, C-reative protein and cortisol (P<0.05), lower growth rate and higher lung pneumonia score. However, regardless of stage, the inflammatory status had no significant effect on plasma testosterone or oestradiol, fat androstenone or sexual organ development. Present data suggest that a mild inflammatory status has no influence on pubertal development or fat concentration of androstenone in boars.     

The influence of insulin administration after weaning the first litter on ovulation rate and embryo survival in sows

Primiparous crossbred sows (n = 43), lactating for an average of 21.1 +/- 0.1 d and weaning 8.7 +/- 0.1 pigs, were used to evaluate the influence of insulin on ovulation rate and embryo survival. The sows were maintained on 2.3 kg/head/d of a 14% protein gestation diet during pregnancy, fed ad libitum during lactation, given 2.7 kg/head/d from weaning until re-breeding and fed 2.3 kg/head/d after mating. Beginning the day after weaning (Day 0) sows were treated with 0.4 IU/kg body weight (BW) insulin (n = 21) or were administered an equivalent volume of saline (n = 22) for 4 d. Beginning on Day 3 and continuing until Day 14 after weaning, the sows were checked for estrus twice daily and were artificially inseminated using pooled semen from 2 fertile boars. At slaughter (days 30 to 40 of gestation), ovaries and uteri were collected, and the ovulation rate, embryo number and viability, and uterine weight and length were evaluated and recorded. Use of insulin decreased the average interval from weaning to estrus compared with saline by increasing percentage in estrus by Day 14 after weaning (5.0 +/- 0.57 vs 6.9 +/- 0.56 d, respectively; P < 0.03). Ovulation rate, number of embryos, embryo survival, and average uterine length and weight were not influenced by insulin treatment. Overall, insulin affected reproductive efficiency in primiparous sows by increasing the percentage of sows in estrus.     

Sexual development and performance in boars exposed prenatally to triamcinolone

The objectives of this study were 1) to investigate the effects of triamcinolone exposure prenatally upon the gonadotropin-gonadal system and 2) to determine whether prenatal exposure affects the onset of puberty and postpuberal development in boars. Two or four litter-mate Yorkshire boars were randomly selected from five litters from sows fed unsupplemented diets and from seven litters from sows fed triamcinolone-supplemented diets. The boars were studied from birth through 30 wk of age. During this 30-wk period, the boars were bled once every 4 wk and testicular and body weight measurements were taken every 2 wk. From weeks 20 to 30 the boars were exposed weekly to an estrous gilt. During this time, the onset and frequency of mounting and ejaculation were recorded and the quality of the semen collected was evaluated. At slaughter, additional data on the male reproductive tract were collected. The prepartal feeding of triamcinolone to sows did not affect either the boars' weight gain or testicular volume during the 30-wk experimental period. Plasma concentrations of testosterone or cortisol also did not differ (P > 0.10) between the groups of boars. However, mounting and ejaculation occurred earlier in triamcinolone-exposed boars, suggesting that prepartal treatment of sows with triamcinolone may have enhanced the development of sexual behavior and onset of puberty in their offspring.     

Reproductive responses to variation in temperature and food supply by house mice: II. Lactation

Lactating HS/Ibg house mice housed at 21 degrees C and 5 degrees C were assigned to 3 feeding regimes: ad libitum, daily rations of 80% of ad libitum, or 60% of ad libitum beginning on the day that they bore litters. Significant interaction between temperature and food restriction was found for litter survivorship, pup survivorship, litter size, female body weight, and cumulative biomass production. The interaction was due to a magnification of the effects of food restriction at the colder temperature: i.e. mice fed ad libitum were similar at the two temperatures, mice fed the 80% ration differed, and mice fed the 60% ration differed to a greater extent. The dominant response to food restriction was cannibalism by females, which might be associated with the rate of loss in body weight by the female on the days preceding cannibalism of one or more pups. Incidents of cannibalism tended to involve a limited number of pups and to be repeated until a sustainable litter size was reached. In 3 of the food-restricted treatments, females weaned relatively large litters of relatively small pups, but in the most severe treatment (in the group fed the 60% ration at 5 degrees C), the females weaned small litters of large pups. The patterns of cannibalism and variable relative investment in individual pups reflect the aggressive breeding strategy of this classic colonizing species.     

Influence of breed and slaughter weight on boar taint prevalence in entire male pigs

Piétrain (P), Large White (LW) and Belgian Landrace stress negative (BN) boars were slaughtered at 50, 70, 90 or 110 kg live weight to investigate breed differences and the effect of slaughter weight on boar taint prevalence. Boar taint was quantified by four different methodologies: sensory evaluation of neckfat heated with a hot iron in the slaughterhouse, sensory evaluation of meat by consumer panels, sensory evaluation of fat and meat by expert panels and laboratory analysis of indole, skatole and androstenone in backfat. Skatole levels in backfat were significantly higher for LW and BN than for P boars. The androstenone levels and the hot iron method revealed a significant interaction between breed and slaughter weight. On the other hand, experts detected an effect of weight on the androstenone odour perception, which was significantly higher in fat from boars slaughtered at 90 kg compared with 50 kg, and significantly higher in meat from boars slaughtered at 110 kg compared with 50 kg. Consumers did not detect differences in the sensory characteristics among breeds or slaughter weight. These results indicate opportunities to minimise the risk of boar taint in entire male pigs by carefully selecting a combination of breed and slaughter weight. Along with the optimal slaughter weight, the effectiveness of reducing boar taint by lowering slaughter weight appeared to be breed dependent.     

Effects of deoxynivalenol (DON) on growth performance, nutrient digestibility and DON metabolism in pigs

Wheat infected naturally withFusarium, contaminated mainly with 18.53 mg DON per kg, was added to a total constant wheat proportion of 400g/kg diet. Control and DON contaminated feed was fed for 11 weeks underad libitum and restrictive feeding conditions to 48 pigs of both sexes, which were randomly divided into 4 groups. Effects on performance (live weight range between 26 and 100kg), duration of feed intake and blood parameters were investigated. Parallel to this study, a balance study was carried out to examine the effects on nutrient digestibility and DON metabolism. The group fed the DON contaminated rationad libitum consumed 15% less feed and gained 14% less live weight compared to thead libitum control group, while the feed to gain ratio was unaffected. Under restrictive feeding conditions (DON and control) pigs exhibited 33%, 25% and 10% lower feed consumption, live weight gain and feed to gain ratio, respectively, than the control group fedad libitum. Metabolizability of energy, digestibility of organic matter, crude protein, crude fat and N-retention were significantly increased by 4, 3, 6, 11 and 10%, respectively, in the DON group of the restrictively fed pigs. In average up to 43.2% of the ingested DON, as the parent toxin in both groups, was eliminated with the urine and up to 3.0% with faeces. DON fed animals needed more time to consume the restrictive ration than the control group. Presented at the 26^th Mykotoxin-Workshop in Herrsching, Germany, May 17–19, 2004. Financial support Deutsone Forschungsgemeingschaft     

Birth weight and postnatal dietary protein level affect performance, muscle metabolism and meat quality in pigs

Intrauterine growth restriction (IUGR), resulting in low birth body weight (LBW) occurs naturally in pigs. However, IUGR may also cause persistent changes in physiology and metabolism resulting in poorer performance, organogenesis and meat quality. As IUGR pigs have a lower daily gain from birth to slaughter they may differ in utilization of nutrients and requirements for dietary protein compared with their larger littermates. Thus, the objective in this study was to examine the interaction between birth body weight (BW) and the postnatal dietary protein level, in relation to postnatal performance, organogenesis, muscle metabolism and meat quality. The experiment was carried out with offspring from 16 purebred Danish Landrace gilts mated to Danish Landrace boars. The female and entire male pigs with LBW that survived at weaning were compared with the female and male pigs with the highest/high birth body weight (HBW) within each litter. The offspring were reared individually from weaning and were fed ad libitum a diet containing either a normal level of protein (NP) for optimal growth or an isocaloric diet containing a 30% lower protein content (LP) from 3 weeks to 150 days of age. At slaughter, we found no interactions between birth weight group and dietary protein level for any of the measured traits. The relative crown-rump length (cm/kg) at birth indicates that LBW pigs were thinner than HBW pigs. Daily gain and feed intake were reduced by 14% and 10%, respectively, while the kg feed/kg gain was slightly increased by 3% in LBW pigs compared with HBW pigs. The LP diet reduced daily gain by 27% due to reduced feed intake and increased kg feed/kg gain by 12% and 21%, respectively compared with the NP diet. LBW male pigs produced meat with a higher shear force than male HBW pigs and also LP pigs produced meat with higher shear force than NP pigs. The activity of lactate dehydrogenase in the Longissimus dorsi muscle (LD) was reduced in pigs fed the LP diet. Calpastatin was increased in LD of LBW pigs and decreased in pigs fed the NP diet. In conclusion, these results suggest a rejection of our hypothesis that low birth weight littermates have a lower requirement for dietary protein compared with heavy weight littermates. Furthermore, LBW male pigs and LP fed pigs of both genders produced less tender meat than HBW pigs or NP fed pigs, respectively.     

Utilization of alkali-treated grain. 1. Alkali-treated grain in complete diets for steers and lambs

In one experiment, 32 lambs were offered (ad libitum) diets based on whole or NaOH-treated barley, or whole or NaOH-treated oats. The live-weight gains from 17 to 35 kg live weight were 371, 290, 258 and 229 g/day, respectively, while the calculated carcass weight gains were 190, 161, 86 and 118 g/day, respectively. There were large differences in the gut contents at slaughter which were 5.0, 3.3, 9.2 and 3.0 kg for the four diets, respectively.Forty-eight, Hereford-cross steers were allocated to six dietary treatments which consisted of unrestricted access to one of the following diets: NaOH-treated barley; rolled barley; NaOH-treated oats; rolled oats; NaOH-treated wheat; or NaOH-treated maize. The steers were fattened from 325 to 425 kg live weight. The average live weight gains were 1.56, 1.91, 1.37, 1.38, 1.49 and 1.42 kg/day, respectively. The steers receiving rolled barley achieved the greatest live weight gains (P < 0.05). The rumen contents at slaughter were 19.8, 32.2, 24.2, 46.0, 20.8 and 18.4 kg, respectively. Because of differences in gut contents, the only significant differences in carcass weight gain were found for the steers receiving rolled oats, for which carcass gain was lower than that for any other treatment (P < 0.001).Sixteen, Hereford-cross steers were allowed free access to diets containing either NaOH-treated barley alone, or NaOH-treated barley mixed with 10% of chopped straw. The live weight gains from 325 to 425 kg live weight were 1.55 and 1.07 kg/day, and food conversion was 5.7 and 8.4 kg feed/kg gain respectively.     

Blood meal as a source of protein for grower/finisher pigs

In the first of four experiments five dietary levels of ring-dried blood meal (0, 3.0, 5.9, 8.9 and 11.8%) were used for pigs of 21–70 kg live weight at two levels of feeding (restricted and ad libitum). Pigs receiving either 5.9 or 8.9% blood meal grew more efficiently than pigs receiving either 0 or 11.8%. The feed conversion ratio of pigs given 3.0% blood meal was of intermediate value. There were significant interactions; when feeding was ad libitum, a reduced intake at the higher levels of blood meal resulted in a slower growth rate at the 11.8% level of blood meal, but with restricted feeding, up to 11.8% blood meal could be included without adverse effects on feed intake or growth rate.In the second and third experiments grower pigs fed ad libitum, between 22 and 50 kg live weight, were used to investigate the effects of the addition of a feed flavour or of isoleucine to a diet containing 12% blood meal. Experiment 2 involved two levels of blood meal (0 and 12%) and two levels of a feed flavour (0 and 50 p.p.m.). The feed flavour failed to prevent the reduction in feed intake and growth caused by 12% blood meal. In the third experiment the addition of 0.1% isoleucine to the 12% blood meal diet significantly increased both intake and growth rate but not to the level of a diet containing no blood meal.In Experiment 4 the digestible energy (± SE) content of blood meal was determined to be 20.8 (± 2.15) MJ/kg dry matter.     

The effect of feeding level on semen quantity and quality of breeding boars

An experiment was carried out to investigate the influence of feeding level on semen quantity and quality in breeding boars in two successive periods of 12 and 8 weeks. Forty-two Yorkshire boars (13 months old) were fed for 12 weeks ad libitum (H=5.74 kg/day), a medium feeding level (M=3.62 kg/day) or a low feeding level (L=1.92 kg/day). After 8 weeks the number of ejaculated sperm cells for boars on treatment L was lower than for those on treatments H and M (P <0.05). In the last 2 weeks, the M and H boars ejaculated 46 and 69% more sperm cells, respectively, than the L boars. Differences between all three feeding levels were significant (P < 0.05). After this 12-week period the feeding level was altered for the H and the L boars. H boars were fed a low feeding level (HL) and L boars were fed the medium feeding level (LM). The medium-fed boars were kept at the same feeding level (MM). After 8 weeks in the second period, differences in the number of ejaculated sperm cells between the HL and MM boars and between the LM and MM boars were no longer significant (P >0.05). Throughout the experiment, no differences in the quality parameters, percentage of moving sperm cells in the ejaculate, vitality of the moving sperm cells and non-return percentage at 56 days were found between treatment groups.     

Methodological developments in the use of visible reflectance spectroscopy for discriminating pasture-fed from concentrate-fed lamb carcasses

The ability to authenticate the feed given to animals from the animal products has become a major challenge for scientists, monitoring bodies and commercial entities alike. This study compared two methods based on the use of the visible reflectance spectrum of the fat to discriminate pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 307 (143 P and 164 S) Limousine lambs were used over 2 years. Pasture-fed lambs grazed a permanent pasture that was maintained at a leafy, green vegetative stage, and offered ad libitum; they received no supplementation at pasture. Body weight of P lambs when turning out to pasture and at slaughter averaged 9.2 (standard deviation (s.d.) 2.21) kg and 33.2 (s.d. 2.89) kg, respectively. S lambs were fed indoors on an ad libitum diet of commercial concentrate and hay until slaughter at a mean body weight of 33.7 (s.d. 3.62) kg. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at slaughter and at 24 h post mortem. Plasma carotenoid concentration was measured at slaughter. In method 1, the fat reflectance spectrum data were used at wavelengths between 450 and 510 nm to calculate an index quantifying light absorption by carotenoid pigments. In method 2, a multivariate analysis was performed over the full set of fat reflectance data at wavelengths between 400 and 700 nm. Method 2 yielded a higher proportion of correctly classified lambs compared with method 1 (P < 0.05 to 0.001), except for measurements made at 24 h post mortem on perirenal fat for S lambs. The proportion of lambs correctly classified using method 2 was 87.4% and 92.9% for measurements made on perirenal and caudal fat at slaughter, and 93.9% and 91.0% for measurements made on perirenal and caudal fat 24 h post mortem. Plasma carotenoid concentrations were higher in P lambs than in S lambs (P < 0.001), which led to correct classification of 90.7% of the lambs.     

Utilization of alkali-treated grain. 3. Utilization by steers of NaOH-treated and rolled barley in silage-based diets

In the first of three experiments, silage constituted 33 or 66% of the dry matter of complete diets, barley being the other component. The barley was either rolled, or treated with 30 g NaOH/kg dry matter. In two further treatments, the NaOH-treated barley was given in separate feeds, while silage was offered ad libitum. The diets were offered ad libitum to 32 Hereford cross steers from 325 kg live weight to slaughter at 450 kg live weight. Growth rate increased and feed conversion ratio decreased as the precentage of barley in the diet increased, but were significantly poorer with NaOH-treated than with rolled barley owing to the significantly lower digestibility of dry matter, organic matter and starch in diets containing NaOH-treated grain.In the second experiment, the effect on digestibility of increasing the NaOH added to the barley used in the mixed diets was investigated with steers. The results showed that the level of NaOH application had to be greater when NaOH-treated barley was used in mixed feeds than when it was used as the sole feed. The optimum rate of application in silage based diets was in the region of 45 g NaOH/kg dry matter.In the third experiment, forty Hereford cross steers were allocated to one of four treatments and were fattened from 325 to about 450 kg live weight. They were given (dry matter basis) 50% silage and 50% of barley, either rolled (RM) or treated with 45 g/kg NaOH (CM), mixed together, or they were given the silage alone until they had eaten the allocated quantity and then the allocated barley; the barley was either rolled (RS) or treated with 30 g/kg of NaOH (CS). The same quantities of silage and grain were given to all steers. The steers fed on silage and grain separately took, on average, 125 days to consume the feed (70 days for consumption of silage), but had similar carcass weights to the steers given mixed diets, which consumed their feed in 91 days. The growth rates for treatments RM, CM, RS and CS, respectively, were 1.15, 1.20, 0.89 and 0.78 kg/day, the food consumption was 737, 741, 728 and 741 kg dry matter and the final carcass weights were 256, 253, 247 and 252 kg. There were no significant differences between steers receiving the diets containing rolled or NaOH-treated barley.     

The effect of hemicastration on sperm reserves of cockerels on a restricted dietary intake,sperm reserves and deposition of sperm in different strains of cockerels

Cockerels from Hyperco-Goldlink layer strain (HPL), Starcross broiler (BSB) and Warren-Ross broiler (WRB) strains were used in this study. They were reared in deep litter until some cockerels from each strain were hemicastrated at 4 weeks of age. Thereafter all the treated birds and their controls were caged individually. Cockerels (HPL) used for the dietary study were divided into four groups: A, intact and fed ad libitum (IAL); B, intact and rationed (IRF); C, hemicastrated and fed ad libitum (HAL); and D, hemicastrated and rationed (HRF).HPL, BSB, WRB were used for the determination of the sperm reserves and deposition. IRF and HRF were fed 60% of normal ration. All others were given water and feed freely. At 7 months of age all the birds were killed and the sperm reserve in each genital tract (testis, epididymis and the vas deferens which was divided into three sections, VD₁, VD₂ and VD₃) was determined.Hemicastration caused an increase of 38.3% in testes weight and 178.6% in sperm reserve in HPL and similarly 53.1% and 138.3% in BSB and 12.2% and 89.9% in WRB respectively. All the values were significant (P < 0.05). Hemicastration caused more sperm to be stored in the testis of hemicastrated birds than in the testes of intact birds; 23.0% in HPL, 17.0% in BSB and 23.0% in WRB. However, in both the intact and hemicastrated birds the highest percentage of sperm was stored in the testis followed by the VD₃, VD₂, VD₁ and epididymis in that order.Compared with the intact controls (A), dietary restriction in (B) caused a 72% fall in testis weight and 75% reduction in sperm reserve. A decrease of 38% in testis weight and 73% in sperm reserve occurred among the hemicastrates in group D birds compared with group C birds. The differences were significant (P < 0.05). Hemicastration increased the right testis weight (281%) and the sperm reserves (192.3%) when the rationed birds in group B and group D were compared. Hemicastration increased the testis weight by 48.3%, and the sperm reserve by 209.7% when group C was compared with the birds fed ad libitum in group A.     

Effect of aqueous leaf extract of Azadirachta indica on the reproductive organs in male mice

Effect of oral administration (50, 100, and 200 mg/kg body weight/day, for 28 days) of aqucous leaf extract of neem (Azadirachta indica) on the male reproductive organs of the Parkes (P) strain mice was investigated. The treatment had no effect on body weight and the reproductive organs weight. In treated mice, testes showed both normal and affected seminiferous tubules in the same sections; the affected seminiferous tubules showed intraepithelial vacuolation, loosening of germinal epithelium, marginal condensation of chromatin in round spermatids, occurrence of giant cells, mixing of germ cell types in stages of spermatogenesis and degenerated appearance of germ cells. In severe cases, the tubules were lined with Sertoli cells only, Sertoli cells and rare germ cells, or with Sertoli cells and several germ cells but without cellular association patterns. Also, the frequency of affected seminiferous tubules in testes of the extract-treated mice was significantly higher than the controls, though this remained unaffected in mice treated at 50 mg/kg body weight of the extract. Doses at 50 or 100 mg/kg body weight of neem leaf extract did not cause appreciable alterations in histological appearance of the epididymis, while a dose of 200 mg/kg body weight caused marked alterations both in histological appearance and the level of sialic acid in the duct. The treatment also had adverse effects on motility, morphology, and number of spermatozoa in the cauda epididymidis, level of fructose in the seminal vesicle, and on litter size. After 42 days of withdrawal of the treatment, the alterations induced in the reproductive organs recovered to control levels. Our results suggested that treatment with neem leaf extract caused reversible alterations in the male reproductive organs of P mice.     

The effects of dietary protein on age and weight at the onset of puberty in Brown Swiss and Zebu heifers in the tropics

The effects of dietary protein level on age and weight at onset of puberty were studied in the Mexican tropics using 12 Brown Swiss and 12 Zebu heifer calves in a completely randomized block design. The calves were weaned at 3 mo of age. They were confined in individual pens and fed either an adequate protein (12.8%) or a high protein (16.4%) diet ad libitum through the onset of puberty, which was defined as the first ovulation. To detect the first ovulation, heifers were palpated at 8 mo of age and then every 2 wk. At the detection of a developing follicle or any behavioral sign of estrus, they were palpated daily. Ovulation was confirmed by palpation of a corpus luteum. A blood sample for the determination of plasma progesterone concentration was taken with each palpation. There was a significant effect of breed on age at the onset of puberty, which was 9.4 and 12.3 mo for the Brown Swiss and Zebu heifers, respectively. Weight at puberty was 233 kg, independent of breed. Dietary protein had no effect on the onset of puberty. Brown Swiss heifers reach puberty earlier than Zebu heifers. Heifers in the tropics fed according to NRC recommendations reach puberty at ages comparable to those in temperate climate. This suggests that, if managed properly, calving age for Brown Swiss and Zebu heifers can be 24 and 27 mo, respectively. This is a considerable improvement from 36 to 48 mo of age now common in the area of study.     

Oral immunization in adult mice to live and heat-killed Vibrio cholerae

Effects of systemic and intestinal local immune responses in mice fed ad libitum and forcedly with live or heat-killed Vibrio cholerae on the elimination of vibrios from the intestine were investigated. In mice fed with live vibrios, ad libitum feeding could induce potential delayed-type hypersensitivity and rapid production of vibriocidal antibody in the serum whereas forcedly feeding suppressed the delayed-type hypersensitivity and retarded the antibody production. In contrast, when killed microorganisms were used as antigens, significant delayed-type hypersensitivity and rapid response of vibriocidal antibody were induced in forcedly fed mice although ad libitum feeding suppressed the induction of the delayed-type hypersensitivity and retarded the production of vibriocidal antibody. The elimination of vibrios from the intestine of mice was promoted in both mice groups fed ad libitum and forcedly with live vibrios but not with killed microorganisms. Total IgA in the intestinal contents of mice fed with live vibrios both ad libitum and forcedly were higher than those of mice fed with killed antigens. In addition, when the extracts of intestinal contents were absorbed by live antigens, IgA contents in mice fed with live vibrios were reduced more markedly than those in mice immunized orally by the feeding with killed antigens. These findings suggested that the elimination of vibrios from the organ was closely related to local IgA antibody response to heat-labile substance of live Vibrio cholerae.