Supplemental lactoferrin improves health and growth of Holstein calves during the preweaning phase.

Lactoferrin is a milk protein that exhibits broad-spectrum antimicrobial properties. Previous studies indicated that supplemental lactoferrin may alter the microbial populations in the gut of nonruminants and increase preweaning weight gains in calves. In the present study, 40 Holstein calves were used to examine the effects of supplemental lactoferrin (0, 1, 2, or 3 g/d) on health, growth, and feed intake from 3 d of age to 2 wk postweaning. Lactoferrin was mixed and fed with a nonmedicated milk replacer. Calves were housed in individual pens and offered a textured, nonmedicated starter and water for ad libitum consumption. Body weight and heart girth were measuredweekly. Intakes of milk replacer and starter were determined daily. Fecal consistency was monitored three times per week. Calves were weaned when they met certain criteria based on body weight gain and starter intake. Preweaning fecal score responded quadratically, with the group fed 1 g/d of lactoferrin having the lowest score. Overall and preweaning number of days medicated responded in the same manner as fecal score. Preweaning average daily gain and gain-to-feed ratio increased linearly with lactoferrin supplementation, whereas postweaning gain-to-feed ratio decreased linearly with lactoferrin. Overall average daily heart girth gain increased linearly with lactoferrin. Body weight, weaning age, and dry matter intake were not different among treatments. Based on the observed improved gain-to-feed ratios, increased average daily gains, improved fecal scores, and reduced morbidity in preweaned calves, it appears that lactoferrin may be a beneficial supplement in the diets of neonatal calves prior to weaning.

Energy utilization and organ mass of Targhee sheep selected for rate and efficiency of gain and receiving high and low planes of nutrition.

Two experiments were conducted to examine changes in usage of energy and visceral organ mass in Targhee lambs selected on the basis of improved rate and efficiency of growth. In Exp. 1, Targhee ram lambs from a breeding line selected for improved growth rate and feed efficiency and a control line that was maintained without selection for 20 yr were provided with either a high (ad libitum) or low (maintenance) plane of nutrition. Rams were slaughtered and weights of the visceral organs were recorded. Analysis of variance, using a factorial model with BW as a covariant, was used to examine effects of lines of breeding, plane of nutrition, interaction between line of breeding and plane of nutrition, and days on feed. Weights of liver, kidneys, rumen, abomasum, and small and large intestines from lambs receiving a high plane of nutrition were, respectively, 39, 25, 12, 28, 40, and 31% greater than weights of those tissues in lambs receiving a low plane of nutrition. Ruminal weights were 13% greater for rams from the select line of breeding than for those from the control line. In Exp. 2, seven Targhee ewe lambs from the select line and eight from the control line were examined for differences in heat production and energy usage by indirect open circuit respiration calorimetry using a completely randomized design. Fasting heat production of lambs from the select line was 7.8% greater than that of lambs from the control line. Partial efficiencies of ME used for maintenance and tissue accretion were not different between lines of breeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Modifications in growth and morphology of ovine jejunal and ruminal epithelia as affected by inert dietary substances.

Thirty-two lambs were used to study the effects of a nondegradable material in the alimentary tract on growth and morphology of ruminal and jejunal epithelia. Lambs were fed isoenergetic rations that differed only by addition of ground polyethylene. Eight of the lambs receiving each diet were given polyurethane cubes orally that were confined to the rumen. Lambs were slaughtered after 30 d; morphological and growth characteristics of the anterior-ventral and posterior-dorsal ruminal epithelia and jejunal epithelia were examined. Weights of the stomach complex were greater (P less than .05; 1.57 vs 1.48 kg) for lambs fed the polyethylene diet. Polyurethane cubes had no effect on weights of the stomach complex and small intestines. Deoxyribonucleic acid levels and both height and width of papillae were greater (P less than .05) in ruminal epithelial from lambs fed the diet with polyethylene than in those from lambs given the control diet. Protein and DNA levels in jejunal epithelia also were affected (P less than .05) by diet, averaging 8.2 mg/cm2 and 510 micrograms/cm2, respectively, for lambs fed the polyethylene diets vs 7.3 mg/cm2 and 417 micrograms/cm2 for lambs fed the control diet, respectively. Average villus height was greater (P less than .05) in jejunal epithelia of lambs fed the control diet than in jejunal epithelia of those given the polyethylene diet (553 vs 466 microns). Polyurethane cubes did not affect growth or morphological characteristics of either ruminal or jejunal epithelia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of albuterol on oxygen uptake and Na+-K+ ATPase activity of jejunal epithelia and liver in chickens.

Changes in metabolic characteristics of the liver and jejunal epithelia as a result of feeding the beta-agonist albuterol to chickens for 3 and 6 weeks were studied. Feeding albuterol resulted in a change in weights of the liver and small intestines. Chickens fed albuterol for 6 weeks had greater levels of plasma nonesterified fatty acids than those fed the control diet. Oxygen uptake by liver and jejunal epithelial tissues were 25 and 26% greater for chickens fed the diet with albuterol than for those fed the control diet, respectively. No changes in Na+-K+ ATPase activity of both liver and jejunal epithelia were detected as a result of feeding albuterol. These findings indicate that certain beta-agonists may elevate thermogenesis in chickens as a result of increasing metabolic rates of splanchnic tissues. However, the changes resulting in altering oxygen uptake in liver and jejunal epithelia due to feeding albuterol were not associated with Na+-K+ ATPase activity.

Effect of dietary bulk on organ mass, fasting heat production and metabolism of the small and large intestines in sheep.

Groups of 10 lambs were fed either a control diet or a diet consisting of 10% polyethylene at isoenergetic levels for 30 d to study the effect of dietary bulk on visceral organ mass and metabolism of mucosa from the jejunum and proximal colon. Fasting heat production was measured using an additional six lambs. Weights of the large intestine, stomach complex and lungs were greater in lambs fed the polyethylene diet than control lambs. Liver and small intestine weights were not affected by diet. Oxygen consumption rates of jejunal mucosa were not affected by diet while a trend existed for oxygen consumption rates of mucosa from the proximal colon to be increased due to feeding polyethylene. Na+,K+ ATPase activity of mucosa from both jejunum and colon was increased due to feeding polyethylene. Fasting heat production, oxygen consumption or carbon dioxide production did not differ with diet. Dietary bulk affects growth and metabolism of visceral organs but metabolic modifications appear different among tissues.

Effect of level of alimentation on visceral organ mass and the morphology and Na+, K+ adenosinetriphosphatase activity of intestinal mucosa in lambs.

Changes in ovine visceral organ mass and small intestinal mucosa morphology and metabolism due to short-term and prolonged modifications in level of alimentation were studied. Thirty-six lambs were fed for 21 d at either 100 or 50% ad libitum levels of intake. For the next 5 d, lambs either remained on the same intake levels or were switched from 100 or 50% or from 50 to 100% ad libitum intake levels and were subsequently slaughtered. Levels of alimentation the last 5 d before slaughter had a significant effect on weights of the large intestine, small intestine, stomach complex and liver, while only the weight of the liver was affected by 21-d adaptation period. Weights of the heart, lungs, carcass and visceral fat were not affected by level of alimentation. Villus height and mucosal mass at a constant intestinal tissue weight were modified by level of alimentation 5 d before slaughter but static to the previous 21-d nutritional plane. Activity of Na+, K+ ATPase of jejunal mucosa was not influenced by level of alimentation 5 d before slaughter, but was influenced by 21-d adapted level of alimentation. Results from this study are interpreted to indicate that weights of the liver and alimentary tract and small intestinal mucosa development are highly sensitive to changes in level of alimentation.

Level of alimentation and line of breeding on oxygen uptake by ovine jejunal mucosa.

Targhee rams from a selected and control line of breeding were provided with the same diet at either 100 or 40% of ad libitum feed intake levels for 28 days. The rams were killed in a serial fashion over a 35-day period. A sample of the jejunum mucosa was taken, and O2 consumption rates with and without ouabain were measured. Total O2 consumption and ouabain-sensitive respiration rates of the jejunal mucosa taken from rams of the select line were greater than for samples taken from the control rams. Line of breeding did not influence the percent of the total O2 consumption that was ouabain sensitive and the proportion of the jejunum that was mucosa. Differences in rates of total and ouabain-sensitive O2 consumption attributed to level of feed intake were not detected as significant. Both the percentage of the total respiration rates that was ouabain sensitive and the proportion of the jejunum that was mucosa were greater for rams fed at high intake levels compared with rams fed at low intake levels. Thus both breeding sheep on the basis of improved growth potential and level of alimentation influenced aspects of jejunal mucosa respiration that was Na+-K+-adenosinetriphosphatase dependent.

The influence of empty body weight and mature weight of the genotype on energy density of empty body gain in growing lambs.

From data reported by authors who had serially determined the chemical composition of the empty body of growing lambs of a wide range of genotypes, the energy density of empty body gains (E/G) at intervals from 20 to 50 kg empty body weight (EBW) were estimated. Energy density of empty body gain was related to the EBW of these lambs and to an approximation of the mature weight for the genotype (MW) obtained from a separate data set. The addition of MW to the function relating E/G to EBW increased the r2 from .793 to .940 and reduced the residual standard deviation from .550 to .300 Mcal/kg. Combining EBW and MW as predictors of E/G provided the following function: E/G = 5.718 + .093 (EBW) - .036 (MW). Energy density of empty body gain was approximately constant across all genotypes when comparisons were made at a constant EBW/MW. Thus, both EBW and mature weight of the genotype are closely related to E/G and should be considered important for accurately predicting net energy of gain requirements for growing lambs.

Changes in the solubility of bovine intramuscular collagen due to nutritional regime.

Longissimus dorsi muscles were removed from the carcasses of 60 Charolais-cross steers in order to examine the relationship between five feeding systems and collagen solubility values obtained by two different methods (warm and cold extractions). Steers were provided with either a 75% concentrate diet, 50% concentrate diet, corn silage diet, corn silage to 400 kg live weight followed by the 75% concentrate diet or alfalfa silage fed to 400 kg live weight followed by the 75% concentrate diet. Steers on the 75% concentrate diet throughout the feeding period required the least time on feed, had the lowest slaughter and carcass weights and produced meat with the highest warm collagen solubility values. Steers fed corn silage continuously needed the longest time on feed, had the lowest daily rates of gain and produced meat with the lowest warm collagen solubility values. Despite being on feed for a longer length of time, steers fed corn silage or alfalfa silage prior to finishing on the 75% concentrate diet produced meat with warm collagen solubility values similar to those continuously fed the 50% concentrate diet. Steers fed the 75% concentrate diet subsequent to forage feeding exhibited greater rates of gain before slaughter while those fed the 75% concentrate diet continuously showed a rapid decline in rate of gain with increasing body weight. Total collagen and cold collagen values were similar among feeding systems. These results indicated that plane of nutrition before slaughter and days on feed both exerted an influence on the properties of intramuscular collagen.