The effect of sodium butyrate (SB) supplementation in milk replacer (MR) or in starter mixture (SM) or in both MR and SM on performance, selected blood parameters, and rumen development in newborn calves was determined. Twenty-eight male calves with a mean age of 5 (±1) d were randomly allocated into 1 of 4 groups (7 animals per group) and fed (1) MR and SM, both without SB (MR(-) and SM(-), respectively); (2) MR(-) and SM supplemented with SB encapsulated within a triglyceride matrix (SM(+), 0.6% as fed; 30:70 butyrate-to-triglyceride matrix); (3) MR supplemented with crystalline SB (MR(+), 0.3% as fed) and SM(-); or (4) MR(+) and SM(+). The MR was offered in an amount equal to 10% of the initial body weight (BW) of each calf. The SM was blended with whole corn grain (50/50; wt/wt) and offered ad libitum as a starter diet (0.3% encapsulated-within-triglyceride matrix SB when SM(+) was fed) from the first day of the trial. Calves were slaughtered at d 21 of a trial (mean age 26±1 d). Addition of SB into MR (MR(+)) positively affected BW and average daily gain, tended to decrease the number of days with electrolyte therapies from d 0 to 7, and tended to positively affect fecal consistency from d 8 to 14 of the trial. Inclusion of SB into SM (SM(+)) increased starter diet intake from d 15 to 21, decreased the number of days with scours, and tended to decrease the number of days with electrolyte therapies in the whole trial period. Both MR(+) and SM(+) increased plasma glucose in the whole trial period and MR(+) increased total serum protein at d 14. The SM(+) increased plasma glucagon-like peptide-2 (GLP-2) concentration at d 7 of the trial when compared with the concentration at d 0. Both MR(+) and SM(+) increased reticulorumen weight and papillae length and width. Based on these results, it can be concluded that addition of SB in MR positively affected BW gain, health, and some metabolic intermediates of calves and it stimulated rumen development indirectly, whereas SB supplementation in SM stimulated rumen development directly. Addition of SB both in MR and SM could be recommended for rearing calves.

Abstract. According to the aerobic capacity model, endothermy in birds and mammals evolved as a correlated response to selection for an ability of sustained locomotor activity, rather than in a response to direct selection for thermoregulatory capabilities. A key assumption of the model is that aerobic capacity is functionally linked to basal metabolic rate (BMR). The assumption has been tested in several studies at the level of phenotypic variation among individuals or species, but none has provided a clear answer whether the traits are genetically correlated. Here we present results of a genetic analysis based on measurements of the basal and the maximum swim-and cold-induced oxygen consumption in about 1000 bank voles from six generations of a laboratory colony, reared from animals captured in the field. Narrow sense heritability (h 2 ) was about 0.5 for body mass, about 0.4 for mass-independent basal and maximum metabolic rates, and about 0.3 for factorial aerobic scopes. Dominance genetic and common environmental (ϭ maternal) effects were not significant. Additive genetic correlation between BMR and the swim-induced aerobic capacity was high and positive, whereas correlation resulting from specific-environmental effects was negative. However, BMR was not genetically correlated with the cold-induced aerobic capacity. The results are consistent with the aerobic capacity model of the evolution of endothermy in birds and mammals. Birds and mammals employ an extravagant economy of energy usage. They spend energy at a rate about 20 times higher than do reptiles (Nagy et al. 1999) and dissipate 20-50% of the energy as basal metabolism for maintenance of basic function (McNab 2002). How such a wasteful strategy of energy use evolved from an energetically frugal strategy is puzzling. This puzzle is the core of a nearly half-centurylong debate on selection forces behind the evolution of endothermy (i.e., the ability to maintain an elevated body temperature by means of metabolic heat production) in birds and mammals (see reviews: Hayes and Garland 1995;Ruben 1995;Farmer 2000Farmer , 2003 Koteja 2000Koteja , 2004McNab 2002;Angilletta and Sears 2003;Gomes et al. 2004).Although several hypotheses concerning the evolution of endothermy have been proposed, only one-the aerobic capacity model-has been subject to extensive empirical testing. According to the model, high basal metabolic rate (BMR) and consequently endothermic thermoregulation, evolved as a correlated response to selection for an ability of sustained locomotor activity, supported by aerobic metabolism (Bennett and Ruben 1979), rather than as a response to direct selection for thermoregulatory capability. A fundamental assumption of the hypothesis is that the aerobic capacity is functionally linked with BMR, which translates into a statistically tractable hypothesis of a positive correlation between BMR and the maximum rate of oxygen consumption (V O2max ), and therefore can be tested against empirical results obtained in extant species. The assumption has been...

The objective of the study was to determine the effect of different liquid feeds on calf small intestine and rumen development. Twenty-one bull calves (5 ± 1 d old) were randomly allocated to 3 groups and fed whole milk (WM), milk replacer (MR; 22% CP and 17.5% fat), or MR supplemented with sodium butyrate (MR+SB; 0.3% as fed). Liquid feed dry matter intake was equal between treatments and amounted to 1% of BW at the beginning of the trial. Starter diet was offered ad libitum. Animals were slaughtered at 26 (± 1) d of age. Calves fed WM had higher average daily gain in the whole trial and higher starter diet dry matter intake between d 15 to 21 of the trial as compared with calves fed MR and MR+SB. Calves fed MR lost on average 1.4 kg of BW within first 14 d of the trial and their BW tended to be lower at d 7, 14, and 21 of the study as compared with calves fed MR+SB. The empty jejunum and ileum weight, crypt depth, mitotic index in the middle jejunum were higher, and apoptotic index tended to be lower in calves fed WM as compared with calves fed MR and MR+SB. Calves fed WM also had higher aminopeptidase N activity in the middle jejunum and tended to have higher maltase activity in the distal jejunum as compared with calves fed MR and MR+SB. The mitotic index was higher and apoptotic index was lower in the middle jejunum, and aminopeptidase A activity tended to be higher in the distal jejunum of calves fed MR+SB as compared with those fed MR. Calves fed WM had greater papillae length and width, and tended to have greater muscle layer thickness as compared with calves fed MR and MR+SB. Reticulorumen weight, reticulorumen weight expressed as percent of whole stomach weight, and papillae length and width were higher in calves fed MR+SB as compared with those fed MR. Additionally, calves fed WM had higher plasma glucose and urea in the whole trial period as compared with calves fed MR and MR+SB, and plasma glucose was higher in calves fed MR+SB as compared with those fed MR. Significant positive Pearson correlations were found between small intestine and reticulorumen weights as well as between activity of brush border lactase, maltase, aminopeptidase A, and aminopeptidase N and reticulorumen weight. Different liquid feeds affect small intestine development, animal growth, solid feed intake and metabolic status of calves and this effect can indirectly influence the development of forestomachs.

According to the aerobic capacity model, endothermy in birds and mammals evolved as a correlated response to selection for an ability of sustained locomotor activity, rather than in a response to direct selection for thermoregulatory capabilities. A key assumption of the model is that aerobic capacity is functionally linked to basal metabolic rate (BMR). The assumption has been tested in several studies at the level of phenotypic variation among individuals or species, but none has provided a clear answer whether the traits are genetically correlated. Here we present results of a genetic analysis based on measurements of the basal and the maximum swim- and cold-induced oxygen consumption in about 1000 bank voles from six generations of a laboratory colony, reared from animals captured in the field. Narrow sense heritability (h2) was about 0.5 for body mass, about 0.4 for mass-independent basal and maximum metabolic rates, and about 0.3 for factorial aerobic scopes. Dominance genetic and common environmental (= maternal) effects were not significant. Additive genetic correlation between BMR and the swim-induced aerobic capacity was high and positive, whereas correlation resulting from specific-environmental effects was negative. However, BMR was not genetically correlated with the cold-induced aerobic capacity. The results are consistent with the aerobic capacity model of the evolution of endothermy in birds and mammals.

The aim of a study was to determine the efficacy of the microbial feed additive containing spores of Bacillus licheniformis and Bacillus subtilis (BioPlus 2B ® ) on performance and health status of rearing calves. Sixty four female Holstein calves, aged on average 16.7 ± 4.5 days, were randomly assigned into two groups of 32 animals: control (C) and BioPlus 2B ® (BP). Milk replacer (MR) and starter mixture (SM) fed to BP group contained 1.32 × 10 9 (±3.2%) and 1.13 × 10 9 (±11.5%) spores of Bacilli strains, respectively. Each calf was fed with 2.25 l of MR two times a day for eight weeks, up to the age of approximately 10 weeks. Starter diet (SD) offered to calves consisted of SM and whole maize grain, which were mixed in ratio 50:50 (wt/wt). Intake of MR was equal in both groups, but SD intake was higher in the whole experiment in the BP group (1075 vs 951 g/d; P<0.01). The BP calves grew faster than C ones in the whole trial (P=0.05), but especially in weeks 3-4 (P<0.05). At the end of the trial the BP calves were about 2.9 kg heavier than the C ones (P<0.001). Feed efficiency, calculated as consumption of ME (MJ) or crude protein (g), was not different between treatments. There were also no differences in the health status and faecal score between treatments. The results of this study suggest the beneficial effect of microbial feed additive containing spores of Bacillus licheniformis and Bacillus subtilis for rearing calves. PROBIOTIC FEED ADDITIVE -CALF PERFORMANCE