Effect of organic pig production systems on performance and meat quality

The present study was carried out to establish knowledge of consequence for setting up guidelines of importance for production of competitive organic pork of high quality. Performance and meat quality characteristics were compared between three organic pig production systems based on indoor housing with access to an outdoor area and a Danish conventional indoor system including 100% concentrate during the finishing feeding stage.The three organic systems used the following three feeding regimes: 100% organic concentrate according to Danish recommendations, 70% organic concentrate (restricted) plus ad libitum organic barley/pea silage and 70% organic concentrate (restricted) plus ad libitum organic clover grass silage, respectively.With exception of a slightly lower daily gain in organic pigs fed 100% concentrate, no significant difference was found in performance and meat quality characteristics compared with results obtained in the conventional system. In contrast and independent of roughage used, organic pigs raised on 70% concentrate had a significant reduction in daily gain (P < 0.001) compared with pigs raised on 100% concentrate, despite the fact that no difference in feed conversion rate was seen between the tested production systems. However, the percentage of leanness increased significantly in meat from organic pigs raised on 70% concentrate plus roughage compared with meat from pigs given 100% concentrate. This was reflected in higher yield (weight) of lean cuts and lower yield of cuts with high fat content from pigs fed 70% concentrate plus roughage. In general, organic feeding resulted in a significantly higher content of polyunsaturated fatty acids in the back fat (1.8%), which increased further when restricted feeding plus roughage (4%) was used. Restricted concentrate feeding gave rise to a decrease in tenderness compared with pork from pigs fed 100% concentrate.     

Effect of roughage source and roughage to concentrate ratio on animal performance and rumen development in veal calves

Sixty-four male Holstein-Friesian × Dutch Friesian veal calves (46 ± 3.0 kg) were used to evaluate the effect of the inclusion of different levels and sources of dietary roughage on animal performance and rumen development. Treatments consisted of 1) C100 = concentrate only; 2) C70-S30 = concentrate (70%) with straw (30%), 3) C70-G30 = concentrate (70%) with dried grass (30%), 4) C70-G15-S15 = concentrate (70%) with dried grass (15%) and straw (15%), 5) C70-CS30 = concentrate (70%) with corn silage (30%), 6) C40-CS60 = concentrate (40%) with corn silage (60%), 7) C70-CS30-AL = concentrate (70%) with corn silage (30%) ad libitum, 8) C70-G15-S15-AL = concentrate (70%) with dried grass (15%) and straw (15%) ad libitum. All dietary treatments were provided in addition to a commercial milk replacer. Concentrate was provided as pellets and roughage was chopped. The dietary treatments 1 to 6 were supplied restrictedly to a maximum of 750 g of dry matter (DM) per day, whereas treatments 7 and 8 were offered ad libitum in combination with a reduced amount of milk replacer. Calves were euthanized after 10 wk. Straw supplementation (C70-S30 vs. C70-G30 and C70-CS30) reduced DM intake, and ad libitum supply of concentrate and roughage increased DM intake. Roughage addition did not affect growth performance. Rumen fermentation was characterized by low pH and high total volatile fatty acids and reducing sugar concentrations. Calves fed ad libitum showed lower ruminal lactate concentrations than calves fed restrictedly. Ammonia concentrations were highest in calves fed C-100 and lowest in calves fed ad libitum. The recovery of CoEDTA (added to milk replacer) varied between 20.5 and 34.9%, indicating that significant amounts of milk entered the rumen. Roughage addition decreased the incidence of plaque formation (rumen mucosa containing focal or multifocal patches with coalescing and adhering papillae covered by a sticky mass of feed, hair and cell debris) and the incidence of calves with poorly developed rumen mucosa. However, morphometric parameters of the rumen wall were hardly influenced by the type and level of roughage. Ruminal polysaccharide-degrading enzyme activities reflected the adaptation of the microorganisms to the dietary concentrate and roughage source. Results indicated that in veal calves, the addition of roughage to concentrate diets did not affect growth performance and positively influenced the macroscopic appearance of the rumen wall.     

The volatile profile of longissimus dorsi muscle of heifers fed pasture, pasture silage or cereal concentrate: implication for dietary discrimination

The aim of this study was to determine the effect of different diets on beef meat volatile organic compounds (VOC). Seven heifers grazed pasture for twelve months (group P); 8 heifers received grass silage ad libitum indoors for six months and then were switched to pasture for six months (group SiP); 8 heifers received grass silage ad libitum indoors for six months and then switched to pasture and also offered 0.5 of the diet dry matter of concentrate for six months (group SiPC); 8 heifers received concentrate for twelve months (group C). The muscle longissimus dorsi was sampled at slaughter and subjected to VOC analysis by SPME-GC-MS. Some aldeyhdes, ketones and furans deriving from lipid oxidation were affected by the treatments. Skatole, 3-undecanone, cuminic alcohol and 1-butanol, 2-methyl allowed the discrimination between animals fed concentrate from animals fed non-concentrate diets. Germacrene D, a terpenoid, was a marker of grass feeding.     

Effects of rearing diet, age at freshening, and lactation feeding system on performance

This two-phase trial involved 83 Holstein heifers. The rearing phase consisted of two diets (alfalfa silage plus corn grain for ad libitum intake vs. corn silage plus urea for ad libitum intake) and two breeding age groups (13 vs. 16 mo). The lactation phase compared the above treatments plus two lactation feeding systems: concentrate fed individually to production versus a TMR. The heifers were assigned randomly to the rearing phase at 7 wk of age and fed their respective diets until 14 d prepartum. They were placed on preassigned lactation diets 14 d prepartum and remained on the lactation phase for 550 consecutive d. Daily gains and height at the withers were similar between forage groups during the first half of the rearing phase; in the second half, the heifers fed alfalfa silage were taller at the withers. Those fed corn silage consumed less DM and CP throughout the rearing phase and gained more BW than the heifers fed alfalfa in the latter half. There were no differences in daily gain or DMI between the breeding age groups. In the lactation phase, the group fed alfalfa for ad libitum intake consumed more DM and gave more milk during the first 90 d of lactation than heifers fed corn silage. However, after 90 d the difference in cumulative milk production was not significant. There were no differences in milk production. FCM, or DMI between breeding age groups. The cows fed concentrate consumed more DM and gave more milk during the first 90 d of lactation. By 550 d, there were no differences. Feeding high levels of corn silage can cause heifers to have lower DMI in early lactation. These differences tend to disappear during the second lactation.     

Dietary restriction improved feed efficiency of inefficient lactating cows

The aim of this study was to reduce voluntary dry matter intake (DMI) to increase feeding efficiency of preclassified inefficient (INE) dairy cows through restricted feeding. We studied the effects of dietary restriction on eating behavior, milk and energy-corrected milk (ECM) production, in vivo digestibility, energy balance, and measures of feed efficiency [residual feed intake (RFI) and ECM/DMI]. Before the experiment, 12 pairs of cows were classified as INE. The 2 dietary treatments consisted of ad libitum feeding versus restricted feeding of the same total mixed ration containing 36.5% roughage. Inefficient cows fed the restricted total mixed ration had a shorter eating time and lower meal and visit frequency, but a similar rate of eating, meal size, and meal duration compared with INE cows fed ad libitum. Compared with the INE cows fed ad libitum, restricted INE cows had 12.8% lower intake, their dry matter and neutral detergent fiber digestibility remained similar, and their ECM yield was 5.3% lower. Feed efficiency, measured as RFI, ECM/DMI, and net energy retained divided by digestible energy intake, was improved in the restricted INE cows as compared with the ad libitum cows. Our results show that moderate DMI restriction has the potential to improve feed efficiency of preclassified INE cows.     

Influence of on-farm production practices on sensory and technological quality characteristics of pork loin

Quality of pork from pigs raised either traditionally (outdoor access or bedded settings with no sub-therapeutic antibiotics or growth promotants in feed) or conventionally (commercial indoor) was evaluated. Pork loins (m. longissimus thoracis et lumborum, LTL) from four hundred pigs from either traditional or conventional production systems (n = 200) fed commercially formulated diets ad libitum were harvested at slaughter. Intramuscular crude fat content and lean color (L* and b*) values were significantly decreased in conventional pork loins. LTL from conventionally-raised pig carcasses showed increased (P < 0.05) mean pH, moisture content and reduced cooking loss and shear force values and had increased tenderness and juiciness scores compared to those from traditionally-raised pig carcasses. Results indicated that pork from conventionally raised pigs was superior to that from traditionally raised pigs in terms of tenderness and juiciness, suggesting that consumers may value pork from traditionally raised pigs on the basis of factors other than eating quality and appearance.     

Plasma growth hormone and insulin during early lactation in cows fed silage based diets.

Peripheral plasma insulin, growth hormone, and blood glucose were determined in 24 dairy cows during early lactation. Blood samples were obtained at 4-day intervals during the first 56 days of experimental lactations 1 and 3 of a 3-lactation experiment. The cows were divided equally among three groups and fed one of the following forage rations for three consecutive lactations: corn silage (18.2 kg/day) plus alfalfa-timothy hay ad libitum; corn silage (18.2 kg/day) plus alfalfa-timothy silage ad libitum; or corn silage ad libitum. These diets were continued throughout the intervening dry periods except in the latter group where corn silage intake was limited if individual animals exhibited excessive body weight gain. Four animals in each group received prepartum supplemental concentrates. The remaining four animals received no prepartum concentrate supplementation. Following parturition, concentrates were fed in increasing amounts to a maximum of 14.6 kg/day during the first 56 days of lactation. Plasma insulin, growth hormone, and blood glucose were not affected by forage diet or prepartum supplemental concentrate feeding. Plasma insulin and blood glucose increased and plasma growth hormone decreased with time after parturition. These changes were correlated with nutrient intake which increased during the experiment. Changes in plasma insulin and growth hormone are related to metabolic adjustments during early lactation.     

Compensatory growth response as a strategy to enhance tenderness in entire male and female pork M. longissimus thoracis

The effects of restrictive feeding strategies aimed at promoting a compensatory growth response were investigated with respect to tenderness improvement in pork M. longissimus thoracis. Compensatory growth response is defined by increased weight in pigs fed ad libitum after a period with restricted feeding compared to pigs fed ad libitum the entire fattening period. Specifically, the aim was to study the sensory textural characteristics after female and entire male pigs have been exposed to restrictions in either energy, protein or both in specific growth periods. It was found that textural differences were caused by feeding strategies and not related to variation in intramuscular fat, which did not vary significantly between genders. The female pigs demonstrated compensatory growth response and the texture was significantly (P<0.001) improved by low dietary level of energy from day 50 to 90 and normal dietary level of protein during the entire feeding period. For the entire male pigs, low level of protein in the late feeding period significantly (P<0.05) improved the texture. Also, low level of protein and normal level of energy in the early feeding period resulted in improved tenderness. However, these texture improvements were deemed not to be an effect of compensatory growth since the entire male pigs did not compensate for the feeding restriction in the early feeding period. The tenderness enhancement for the entire male pigs compromised the production results in terms of 7-15% lower carcass weight.     

Response of lactating jersey cows fed concentrate twice daily by computer or in a total mixed ration

Two trials were conducted with 36 Jersey cows each to compare intake, production response, and relative economics of four concentrate management systems. Cows were assigned for 25 wk to concentrate fed: 1) for ad libitum consumption twice daily for 10 min, 2) twice daily according to production, 3) via computer feeder according to production, or 4) as part of a total mixed ration. Concentrate was fed at the rate of 1 kg/3.5 kg 4% FCM for treatments 2 and 3 and at the same rate, but to group average FCM, for treatment 4. Concentrate allotments were updated weekly. Cows were individually fed blended corn silage and whole cotton-seed (84:16, DM basis) plus 2.2 kg alfalfa hay/d (Trial 2 only). Concentrate DM intake was 2.3 kg lower and forage DM intake 2.3 kg higher when cows were fed to production (treatments 2, 3, and 4). Milk production was highest in both trials for treatment 2. Fat test was lowest for twice daily ad libitum feeding with no differences found between other methods. Body weight change was similar across treatments and trials. Milk income was similar, fed costs higher, and income over feed cost lower for treatment 1 than for other methods in both trials. Three methods of feeding concentrate according to production were equally effective in maximizing profit.     

Nighttime pasture access: Comparing the effect of production pasture and exercise paddock on milk production and cow behavior in an automatic milking system

With increasing intensification of the dairy sector in many countries and with the introduction of automatic milking, exercise paddocks combined with full indoor feeding, as an alternative to production pasture, are being used as a compromise between farm economics and cow welfare. This study examined whether there are production benefits for high-producing dairy cows in an alternative system that uses pasture at a level of approximately 50% of the total roughage intake in the diet. In an automatic milking system with 12-h night access to the outdoor environment, we compared milk production and behavior of cows in 2 systems: an exercise paddock combined with ad libitum grass silage indoor feeding and a production pasture combined with a restricted daytime grass silage ration. There were 20 cows in the former and 21 cows in the latter system, with the treatments running in parallel. The experiment started in late June with no complete darkness during the night, and lasted for 12 wk, with 5.6 h of darkness at the end. We therefore also explored the effect of night length on milk production and behavior parameters. All cows showed strong motivation for going outdoors and grazing when pasture access was given in early evening, but after a few hours both groups went to the barn and did not return to the pasture area during the remaining night. As the season progressed and nights became longer, cows on the exercise paddock treatment reduced time spent outdoors and grazing time, whereas they increased time spent resting outdoors. The group on exercise paddock had a greater milk yield (kg of milk) over the experimental period than the production pasture group. The latter group also showed a greater drop in milk yield over the duration of the trial. Thus, for cows milked in an automatic milking system and offered nighttime outdoor access, no milk production benefits were observed in offering production pasture with restricted indoor silage allowance instead of an exercise paddock with ad libitum silage. We therefore suggest that automatic milking farmers with similar production levels and automatic milking-management systems as in the present experiment, who wish to include grazed grass as part of the dairy cow diet, should ensure that cows have pasture access in the afternoon and evening.     

Utilization of protein in red clover and alfalfa silages by lactating dairy cows and growing lambs

Feeding trials were conducted with lactating cows and growing lambs to quantify effects of replacing dietary alfalfa silage (AS) with red clover silage (RCS) on nutrient utilization. The lactation trial had a 2 × 4 arrangement of treatments: AS or RCS fed with no supplement, rumen-protected Met (RPM), rumen-protected Lys (RPL), or RPM plus RPL. Grass silage was fed at 13% of dry matter (DM) with AS to equalize dietary neutral detergent fiber (NDF) and crude protein contents. All diets contained (DM basis) 5% corn silage and 16% crude protein. Thirty-two multiparous (4 ruminally cannulated) plus 16 primiparous Holstein cows were blocked by parity and days in milk and fed diets as total mixed rations in an incomplete 8 × 8 Latin square trial with four 28-d periods. Production data (over the last 14 d of each period) and digestibility and excretion data (at the end of each period) were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Although DM intake was 1.2 kg/d greater on AS than RCS, milk yield and body weight gain were not different. However, yields of fat and energy-corrected milk as well as milk content of fat, true protein, and solids-not-fat were greater on AS. Relative to AS, feeding RCS increased milk and energy-corrected milk yield per unit of DM intake, milk lactose content, and apparent N efficiency and reduced milk urea. Relative to AS, apparent digestibility of DM, organic matter, NDF, and acid detergent fiber were greater on RCS, whereas apparent and estimated true N digestibility were lower. Urinary N excretion and ruminal concentrations of ammonia, total AA, and branched-chain volatile fatty acids were reduced on RCS, indicating reduced ruminal protein degradation. Supplementation of RPM increased intake, milk true protein, and solids-not-fat content and tended to increase milk fat content. There were no silage × RPM interactions, suggesting that RPM was equally limiting on both AS and RCS. Supplementation of RPL did not influence any production trait; however, a significant silage × RPL interaction was detected for intake: RPL reduced intake of AS diets but increased intake of RCS diets. Duplicated metabolism trials were conducted with lambs confined to metabolism crates and fed only silage. After adaptation, collections of silage refusals and excreta were made during ad libitum feeding followed by feeding DM restricted to 2% of body weight. Intake of DM was not different when silages were fed ad libitum. Apparent digestibility of DM, organic matter, NDF, and hemicellulose was greater in lambs fed RCS on both ad libitum and restricted intake; however, acid detergent fiber digestibility was only greater at restricted intake. Apparent and estimated true N digestibility was substantially lower, and N retention was reduced, on RCS. Results confirmed greater DM and fiber digestibility in ruminants and N efficiency in cows fed RCS. Specific loss of Lys bioavailability on RCS was not observed. Based on milk composition, Met was the first-limiting AA on both silages; however, Met was not limiting based on production and nutrient efficiency. Depressed true N digestibility suggested impaired intestinal digestibility of rumen-undegraded protein from RCS.     

Effect of peripartum energy concentration on production performance of Holstein cows

Ninety multiparous Holstein cows were used to measure the effect of energy during the prepartum and postpartum periods. During the prepartum period (63 d) half of the cows were fed grass silage ad libitum and a concentrate (16% protein) was offered daily at .25% of BW. The other half of the cows were offered the silage ad libitum but concentrate at .75% of BW. At calving each of the two prepartum groups was subdivided into three subgroups and fed corn silage for ad libitum consumption, 4.5 kg of hay/d and concentrate (20% protein) at .25 or .75% of BW daily, or ad libitum. After 112 d of lactation, all cows were switched to a diet consisting of corn silage fed ad libitum and 1 kg of concentrate (20% protein)/4 kg of milk. Roughage intake was reduced with an increase of concentrate consumption. Body measurements, calf weight, milk yield, feed efficiency, services per conception, and incidence of diseases were not influenced by the prepartum regimen. However, the interval from parturition to conception was 24 d longer for cows on the higher prepartum energy concentration (.75% of BW). None of the cows was able to meet its nutrient requirement in early lactation. Milk yield increased with each increment of concentrate in the postpartum diet. Reproduction and health were not affected by the postpartum regimen.     

Effect of grain level and protein source on ruminal fermentation, degradability, and digestion in milking cows fed silage

Five primiparous Holstein cows (483 kg BW) of low productivity were used in a 4 x 5 incomplete Latin square design to study the effects of feeding two levels of grain containing soybean meal and one level of grain containing fish meal on feed intake, milk production, digestibility, and rumen fermentation. Animals all were fed alfalfa silage for ad libitum intake. Collection of data was between wk 11 and 24 of lactation. The four treatments were an all silage diet (control), silage and medium concentrate fed at 1.8% BW containing soybean meal, and silage and low concentrate fed at 1.3% BW containing either soybean meal or fish meal. Treatments other than control were designed to give similar CP intake from the concentrate, which was based on high moisture corn and cob meal. Milk production and composition were similar among treatments except for fat percentage, which was significantly lower for low grain soybean meal. Intake of DM was higher on medium grain soybean meal compared with the other treatments. Average BW and change in BW (.11 kg/d) were not affected by treatments. Digestibility of DM was higher for cows fed grain (68 to 73%) than for those fed the control diet (60%). Generally, feeding concentrate at 1.3 or 1.8% BW and supplementing with soybean meal or fish meal resulted in pH and concentrations of NH3 N and VFA similar to those observed on the all silage diet. Feeding concentrate at 1.3 or 1.8% BW and supplying fish meal or soybean meal did not change feed utilization enough to increase milk production in low producing cows compared with an all silage diet.     

Effect of restricted feeding and realimentation periods on pork quality and fatty acid profile of M. longissimus thoracis

An experiment with 94 fattening pigs (48 gilts and 46 barrows) was conducted to determine the effect of feeding 25% restricted diets at different body weights on meat quality and fatty acid profile of M. longissimus thoracis (LT). During the 84 days of the experiment (4 periods, 21 days each), animals with an initial weight of about 31 kg were fed in different periods of observation ad libitum (A) or restricted diets (R) in groups AAAA, AARA, RAAA and RARA. After 21 days of the experiment, the restricted-fed pigs, compared to those fed ad libitum, had a lower total fat content of M. longissimus thoracis (P<0.05), higher shear force (P=0.068), and lower proportions of SFA (C14:0, C18:0 P<0.05) and MUFA and higher proportions of PUFA (C20:4, C22:4 P<0.05) in the fatty acid profile. Three weeks after the restricted feed supply was lifted, the total fat content in LT muscle was higher than in animals fed ad libitum throughout (2.34 vs. 2.02), very close after the next 3 weeks of realimentation (3.16 vs. 3.15) and lower after another 3 weeks (3.19 vs. 3.49). Regardless of the time at which restricted feeding was started and the number of restricted feeding periods, the total fat content in the LT muscle at the end of the experiment was similar or lower in groups RAAA, AARA and RARA, compared to group AAAA. The coefficient of correlation between the total fat content in LT and the shear force was -0.36 (P<0.01). Colour, pH and drip loss did not depend on the level of nutrition. After 84 days of observation, animals from groups RARA and AARA, compared to pigs from groups AAAA and RAAA, were characterized by a slightly higher shear force of LT, lower SFA and MUFA (P<0.001), and higher n-6 PUFA (P<0.01) and n-3 PUFA (P<0.01) proportions in the fatty acid profile. The fatty acid profiles of AAAA pigs and pigs undergoing a 63-day realimentation period (RAAA) were similar. Regardless of the feeding scheme, the n-6:n-3 ratio exceeded 10 in all the groups.     

Effect of reduced ferulate-mediated lignin/arabinoxylan cross-linking in corn silage on feed intake, digestibility, and milk production

Cross-linking of lignin to arabinoxylan by ferulates limits in vitro rumen digestibility of grass cell walls. The effect of ferulate cross-linking on dry matter intake (DMI), milk production, and in vivo digestibility was investigated in ad libitum and restricted-intake digestion trials with lambs, and in a dairy cow performance trial using the low-ferulate sfe corn mutant. Silages of 5 inbred corn lines were fed: W23, 2 W23sfe lines (M04-4 and M04-21), B73, and B73bm3. As expected, the W23sfe silages contained fewer ferulate ether cross-links and B73bm3 silage had a lower lignin concentration than the respective genetic controls. Silages were fed as the sole ingredient to 4 lambs per silage treatment. Lambs were confined to metabolism crates and fed ad libitum for a 12-d adaptation period followed by a 5-d collection period of feed refusals and feces. Immediately following the ad libitum feeding trial, silage offered was limited to 2% of body weight. After a 2-d adaptation to restricted feeding, feed refusals and feces were collected for 5 d. Seventy Holstein cows were blocked by lactation, days in milk, body weight, and milk production and assigned to total mixed ration diets based on the 5 corn silages. Diets were fed for 28 d and data were collected on weekly DMI and milk production and composition. Fecal grab samples were collected during the last week of the lactation trial for estimation of feed digestibility using acid-insoluble ash as a marker. Silage, total mixed ration, feed refusals, and fecal samples were analyzed for crude protein, starch, neutral detergent fiber (NDF), cell wall polysaccharides, and lignin. The W23sfe silages resulted in lower DMI in the ad libitum trial than the W23 silage, but DMI did not differ in the restricted trial. No differences were observed for NDF or cell wall polysaccharide digestibility by lambs with restricted feeding, but the amount of NDF digested daily increased for lambs fed the M04-21 W23sfe silage ad libitum. Lambs were less selective against NDF and lignin when offered W23sfe silages. The B73bm3 silage did not affect DMI or digestibility of cell walls at the restricted feeding level, but total daily NDF digested was greater at ad libitum intake. Intake, milk production, and cell wall digestibility were greater for cows fed diets containing W23sfe silages than for those fed W23 silage. Although milk production was greater for the B73bm3 diet, DMI and cell wall digestibility were not altered. Cows were less selective against cell wall material when fed both W23sfe and B73bm3 silages. Reduced ferulate cross-linking in sfe corn silage is a new genetic mechanism for improving milk production.     

Effects of age and/or weight at slaughter on longissimus dorsi muscle: Biochemical traits and sensory quality in pigs

The effect of increasing either age alone through feed restriction, or both age and weight at slaughter, on the quality of the longissimus dorsi muscle (LM) was investigated. Starting at 83 days of age and 32 kg, 80 pigs were allotted within litter to four experimental groups. All pigs were free of RYR1 mutated gene. Pigs were fed either ad libitum (A100, A130) or restricted 30% (R100, R130) and slaughtered at either 100 kg (A 100, R100) or 130 kg (A130, R130) body weight. Restricting feed intake in order to increase age at the same weight resulted in slower growth, better feed efficiency and increased leanness, whereas increasing age and weight simultaneously elicited slower growth, reduced feed efficiency and fatter carcasses. Intramuscular fat (IMF) and muscle collagen concentration were reduced by restricted feeding. Increase in both age and weight of pigs resulted in lower water, and higher protein and IMF concentrations. Although pigs were free of RYR1 gene, the PSE condition (defined as pH1 ≤ 5.9) developed in 25 carcasses, with a higher incidence in restricted pigs. PSE animals were excluded from the subsequent analysis of meat quality data. Feed restriction resulted in higher drip loss and lower a^* and c^* (saturation index) values. Longer myofibril fragments in muscle of restricted pigs on day 1 post mortem are indicative of slower maturation, while longer fragments on day 4 in heavier pigs, suggest that the extent of post mortem tenderisation could be negatively affected by the elevation of slaughter weight. Feed restriction had no significant effect on meat sensory quality, whereas increase in both age and weight resulted in lower tenderness, chewiness and mouth coating scores. Our results indicate that increasing age at a given body weight, via feed restriction, reduced IMF and collagen concentrations, and the rate of post mortem proteolysis, however, this had no significant impact on pork quality assessed after 4 days of ageing. On the other hand, increasing both age and weight at slaughter could alter pork texture, in spite of elevated IMF concentration.     

Effects of brown midrib corn silage on the energy balance of dairy cattle

Effects of genotype and level of intake on net energy for lactation values of corn silage were evaluated by indirect calorimetry in two experiments using lactating and dry, nonpregnant dairy cows. In experiment 1, six multiparous Holstein cows in early lactation were fed experimental diets containing either brown midrib (bm3) or isogenic normal corn silage. Dietary treatments were isogenic and bm3 diets fed ad libitum, and the bm3 diets restricted-fed. Dry matter (DM) intake was 2.4 kg/d greater for cows fed the bm3 diet ad libitum compared with cows fed the isogenic diet. Apparent digestibilities of DM, organic matter, neutral detergent fiber, and acid detergent fiber were greater for cows restricted-fed bm3 than the isogenic diet. In experiment 2, six dry, nonpregnant Holstein cows were fed maintenance diets containing either bm3 or isogenic corn silage. Apparent digestibilities of DM, organic matter, neutral detergent fiber, and acid detergent fiber were greater for cows fed bm3 compared with isogenic corn silage. Digestible energy and metabolizable energy were greater for maintenance diets containing bm3 compared with isogenic corn silage, respectively. These data indicate increased milk production seen in other studies is a result of increased DMI rather than an increase in energy efficiency. Increased organic matter digestibility of bm3 corn silage resulted in greater digestible energy and metabolizable energy values in cows fed at maintenance energy intake. However, calculated net energy for lactation values of bm3 and isogenic corn silages were similar at both productive and maintenance levels of feeding.     

Secretion of luteinizing hormone and follicle-stimulating hormone from overfeeding dairy heifers

Secretory effects of gonadotropins and various ovarian and uterine measurements were investigated in 22 prepubertal or postpubertal dairy heifers fed a concentrate to forage ration (60:40) in restricted or ad libitum amounts until they gained 125 kg. Average daily gain of heifers on restricted feeding was 613 g compared with 1218 g for heifers fed for ad libitum intake. During three stages of the experiment blood was collected either at 30-min intervals for two 4-h periods (Stage I and III) or at frequent intervals before and after an injection of luteinizing hormone-releasing hormone (Stage II). At the end of Stage III, all heifers were slaughtered, and ovaries and uteri were collected. Of the variables measured in ovaries and uteri, nutrition affected only number of uterine caruncles (76.5 in ad libitum versus 59.7 in restricted-fed heifers). Excess feeding increased frequency of luteinizing hormone pulses during Stage I but not during Stage II. However, amplitude baseline and overall concentrations of luteinizing hormone were unaffected. Release of luteinizing hormone induced by luteinizing hormone-releasing hormone was reduced in heifers with ad libitum intake. Secretion of follicle-stimulating hormone was not affected by overfeeding.     

Transfer of the Meat Aroma Precursors (Dimethyl Sulfide, Dimethyl Disulfide and Dimethyl Trisulfide) from Feed to Cooked Pork

Eight pigs were given standard concentrate feed to a live weight of 70 kg. Subsequently half the pigs were controls and were fed the concentrate feed, while the other half of the pigs were fed an experimental diet consisting of the concentrate feed (89 percent of calories) and Brussels sprouts (11 percent of calories) the last 4 weeks before slaughter. Analyses of volatiles in chops and gastro-intestinal contents were performed using solid-phase micro extraction and subsequent characterization by gas chromatography-mass spectrometry. The ratio between the amount of dimethyl sulfide found in the stomach contents from pigs fed Brussels sprouts and the stomach contents from pigs fed the control diet was 9.0, and correspondingly the ratio was 475.5 for dimethyl disulfide and 8.3 for dimethyl trisulfide. The ratio between the amount of dimethyl sulfide found in meat from pigs fed Brussels sprouts and meat from pigs fed the control diet was 14.9, and correspondingly the ratio was 4.8 for dimethyl disulfide and 1.9 for dimethyl trisulfide. Moreover, several other compounds seem to be influenced by feed composition. Finally, the increase in concentration of sulfur compounds in meat in relation to pork aroma is discussed.