Effects of inclusion level and source of dietary sodium on performance and meat characteristics of broiler chickens

The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO₃ and Na₂SO₄) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCl and Na₂SO₄) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1–14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO₃, Na₂SO₄ seemed to be a better alternative for NaCl. Na₂SO₄ also tended to surpass NaHCO₃ as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.     

Meat meal in the diet of the early-weaned pig IV. The supplementation of diets with tryptophane,lysine and methionine

Two experiments were conducted with 72 pigs between 28 and 56 days of age to study the effect of tryptophane supplementation on their performance when fed on diets containing wheat and meat meal.In the first experiment, pigs were fed on a basal diet (Diet 1) or on the same diet supplemented with calcium dihydrogen phosphate (Diet 2), bone meal (Diet 3) or bone meal plus tryptophane (Diet 4), all to 3.1% calcium. The weight gains of the pigs (315 g day^?1) fed on Diet 3 were significantly lower than that of the pigs fed on the other three diets (363 g day^?1). The feed conversion ratios showed a similar trend. Diet 3 contained 0.16% tryptophane while the other diets contained 0.18–0.19% tryptophane. The crude protein, lysine and methionine contents of all diets were similar.In the second experiment, a basal diet containing meat meal and bone meal was supplemented with tryptophane, lysine plus methionine or all three amino acids. Feed intake was increased by all amino acid supplements. Weight gains were improved significantly (57%) by the addition of all three amino acids to the diets, but the improvements due to tryptophane alone (28%) or methionine plus lysine (35%) were not significant. Tryptophane supplementation alone or with lysine plus methionine increased the nitrogen retention of the pigs.It was concluded that the requirement for tryptophane of pigs between 28 and 56 days of age was greater than 0.16% of diets containing wheat and meat meal.     

Effect of various levels of supplementation with sodium pivalate on tissue carnitine concentrations and urinary excretion of carnitine in the rat

In previous studies, sodium pivalate has been administered to rats in their drinking water (20 mmoles/L; equivalent to 0.3% of the diet) as a way to lower the concentration of carnitine in tissues and to produce a model of secondary carnitine deficiency. Although this level of supplementation results in a marked decrease in carnitine concentration in a variety of tissues, it does not produce the classical signs of carnitine deficiency (i.e., decreased fatty acid oxidation and ketogenesis). The present study was designed (1) to determine if increasing the level of pivalate supplementation (0.6, 1.0% of the diet) would further reduce the concentrations of total and free carnitine in rat tissues without altering growth or food intake, and (2) to examine the effect of length of feeding (4 vs. 8 weeks) on these variables. Male, Sprague-Dawley rats were randomly assigned to either a control (0.2% sodium bicarbonate) or experimental diet (0.3, 0.6, 1.0% sodium pivalate) for either four or eight weeks. Animals (n = 6/group) were housed in metabolic cages; food and water were provided ad libitum throughout the study. Supplementation with sodium pivalate did not alter water intake or urine output. Ingestion of a diet containing 1.0% pivalic acid decreased food intake (g/day; P < 0.05), final body weight (P < 0.007), and growth rate (P < 0.001) after four weeks. The concentration of total carnitine in plasma, heart, liver, muscle, and kidney was reduced in all experimental groups (P < 0.001), regardless of level of supplementation or length of feeding. The concentration of free carnitine in heart, muscle, and kidney was also reduced (P < 0.001) in rats treated with pivalate for either four or eight weeks. The concentration of free carnitine in liver was reduced in animals supplemented with pivalate for eight weeks (P < 0.05), but no effect was observed in livers from rats treated for four weeks. Excretion of total carnitine and short chain acylcarnitine in urine was increased in pivalate supplemented rats throughout the entire feeding period (P < 0.001). Free carnitine excretion was increased during Weeks 1 and 2 (P < 0.01), but began to decline during Week 3 in experimental groups. During Weeks 6 and 8, free carnitine excretion in pivalate supplemented rats was less than that of control animals (P < 0.01). In summary, no further reduction in tissue carnitine concentration was observed when rats were supplemented with sodium pivalate at levels greater than 0.3% of the diet. Food intake (g/day) and growth were decreased in rats fed a diet containing 1.0% sodium pivalate. These data indicate that maximal lowering of tissue carnitine concentrations is achieved by feeding diets containing 0.3% sodium pivalate or less.     

Dietary supplementation with sodium bicarbonate or sodium sulfate affects eggshell quality by altering ultrastructure and components in laying hens

Dietary sodium (Na) levels were related to the content of the eggshell matrix. We therefore speculated that dietary Na supplementation as sodium bicarbonate (NaHCO₃) or sodium sulfate (Na₂SO₄) may improve eggshell quality. Additionally, dietary NaHCO₃ or Na₂SO₄ supplementation may further affect eggshell quality in different ways due to differences in anions. This study investigated and compared the effects of dietary Na supplementation in either NaHCO₃ or Na₂SO₄ form on laying performance, eggshell quality, ultrastructure and components in laying hens. A total of 576 29-week-old Hy-Line Brown laying hens were randomly allocated to 8 dietary treatments that were fed a Na-deficient basal diet (0.07% Na, 0.15% Cl) supplemented with Na₂SO₄ or NaHCO₃ at 0.08, 0.18, 0.23 or 0.33% Na for 12 weeks. No differences were observed in laying production performance with dietary Na supplementation. Dietary Na supplementation resulted in quadratic increases of eggshell breaking strength in both Na₂SO₄ and NaHCO₃ added groups (P < 0.05), and Na₂SO₄-fed groups had a quadratic increase in the eggshell ratio at week 12 (P < 0.05). Compared with supplementing 0.08% Na, dietary supplementation of 0.23% Na increased the effective thickness (P < 0.05) in both Na₂SO₄ and NaHCO₃ added groups, but decreased the thickness and knob width of the mammillary layer (P < 0.05). A linear increase on the calcium content of the shell was only observed with Na supplementation from NaHCO₃ (P < 0.05). No differences were observed in Na contents of the shell with dietary Na supplemented by both sources. Dietary Na addition had a quadratic increase on uronic acid contents of shell membrane in NaHCO₃-fed groups (P < 0.05). Moreover, the sulfated glycosaminoglycan (GAG) contents of shell membranes increased linearly with dietary Na supplementation (P < 0.05). Dietary supplementation of 0.23% Na from Na₂SO₄ increased the sulfated GAG contents of calcified eggshell (P < 0.05). Additionally, compared with NaHCO₃-fed groups, Na₂SO₄-fed groups had higher eggshell breaking strength, thickness, eggshell weight ratio, effective thickness and the sulfated GAG contents of calcified eggshell at week 12. Overall, dietary supplementation of NaHCO₃ or Na₂SO₄ could increase eggshell breaking strength, which may be related to increased sulfated GAG contents in eggshell membranes and improved ultrastructure. Higher eggshell breaking strength, thickness and eggshell ratio could be obtained when the diet was supplemented with 0.23% Na from Na₂SO₄.     

Differential effects of dietary sodium intake on blood pressure and atherosclerosis in hypercholesterolemic mice

The amount of dietary sodium intake regulates the renin angiotensin system (RAS) and blood pressure, both of which play critical roles in atherosclerosis. However, there are conflicting findings regarding the effects of dietary sodium intake on atherosclerosis. This study applied a broad range of dietary sodium concentrations to determine the concomitant effects of dietary sodium intake on the RAS, blood pressure, and atherosclerosis in mice. Eight-week-old male low-density lipoprotein receptor ?/? mice were fed a saturated fat-enriched diet containing selected sodium concentrations (Na 0.01%, 0.1%, or 2% w/w) for 12 weeks. Mice in these three groups were all hypercholesterolemic, although mice fed Na 0.01% and Na 0.1% had higher plasma cholesterol concentrations than mice fed Na 2%. Mice fed Na 0.01% had greater abundances of renal renin mRNA than those fed Na 0.1% and 2%. Plasma renin concentrations were higher in mice fed Na 0.01% (14.2±1.7 ng/ml/30 min) than those fed Na 0.1% or 2% (6.2±0.6 and 5.8±1.6 ng/ml per 30 min, respectively). However, systolic blood pressure at 12 weeks was higher in mice fed Na 2% (138±3 mm Hg) than those fed Na 0.01% and 0.1% (129±3 and 128±4 mmHg, respectively). In contrast, mice fed Na 0.01% (0.17±0.02 mm²) had larger atherosclerotic lesion areas in aortic roots than those fed Na 2% (0.09±0.01 mm²), whereas lesion areas in mice fed Na 0.1% (0.12±0.02 mm²) were intermediate between and not significantly different from those in Na 0.01% and Na 2% groups. In conclusion, while high dietary sodium intake led to higher systolic blood pressure, low dietary sodium intake augmented atherosclerosis in hypercholesterolemic mice.     

Meat meal in the diet of the early-weaned pig. II. Amino acid supplementation

One hundred and twenty pigs, initially 4–5 kg liveweight, were fed on wheat-based diets supplemented with meat meal and amino acids in two experiments, each of 4 weeks duration.In the first experiment, the supplementation of a normal meat meal diet with lysine and methionine increased the feed intake and weight gains of the pigs by 15 and 18%, respectively. Nitrogen retention was increased by 30%. Tryptophane gave a similar response to lysine and methionine.In the second experiment, a 21% crude protein basal diet was similar to the basal diet of the first experiment but it contained 1.02% lysine and 0.50% methionine plus cystine, compared to 0.90 and 0.51%, respectively, in the first experiment. Lysine and methionine supplementation of the diet did not significantly improve the performance of the pigs in the second experiment, but the supplementation of the diets with 0.08% tryptophane and lysine and methionine increased weight gains and feed intakes and decreased urea content of the blood plasma. The 21% crude protein diet contained 0.15% tryptophane.Increasing the crude protein content of diets from 18 to 24% by increasing their meat meal content increased the daily weight gains from 190 to 276 g.     

杏仁中央核损毁对缺钠大鼠钠欲行为启动和表达的影响

目的:探讨杏仁中央核(CeA)损毁对缺钠大鼠钠欲行为启动和表达的影响。方法:将18只成年雄性SD大鼠随机分为3组(n=6):双侧Ce A损毁组、假损毁组和不损毁组,手术恢复后给予大鼠14 d低钠饲料摄食以建立缺钠大鼠模型,运用单笼双瓶选择测试方法观察缺钠大鼠在24 h内5个不同时间段对0.3 mol/L NaCl和自由饮水的摄入情况。应用免疫荧光化学染色方法观察杏仁中央核损毁与否对缺钠或正常大鼠孤束核内醛固酮敏感神经元活动的影响。结果:低钠饮食14 d后,大鼠对0.3 mol/L NaCl 24 h内饮用量和偏爱率比低钠饮食前明显增加(P<0.01);杏仁中央核损毁后缺钠大鼠对0.3 mol/L Na Cl溶液的摄入量和偏爱率显著下降(P<0.01)。杏仁中央核损毁对低钠饮食诱发的大鼠孤束核内醛固酮敏感神经元活动增加没有影响。结论:低钠饮食诱导大鼠钠欲行为表达增加;杏仁中央核损毁压抑缺钠大鼠钠欲行为的表达,而对缺钠大鼠的钠欲行为的启动没有影响。     

Effects of alginates and sodium carrageenates mixed with soy proteins on the coefficient of protein efficiency

Male 21 d-old Wistar rats, were fed for 4 wk with diets containing casein or soybean proteins (10%) with 0.5, 1, 2 or 3% sodium alginate or sodium carrageenan or without any alginate or carrageenan. Daily protein intake and weight gain of casein-fed rats were not significantly different (P less than 0.05) from those of rats fed soybean meal with alginate, whatever the dose received. Rats fed 3% carrageenan in soybean meal had significantly higher feed intake than that of rats fed casein. At the levels studied, alginate had no effect on the Protein Efficiency Ratio (PER), but carrageenan did. The addition of increased quantities of carrageenan to soybean meal followed by heating the mixture led to a progressive and significant decrease in PER at all levels of carrageenan compared to casein feeding. The addition of 3% carrageenan to heated soybean meal, corresponding to 0.62% of meal diet, led to a significant decrease in PER. These results confirm the precipitating role of carrageenans on proteins.     

食物单宁酸对根田鼠(Microtus oeconomus)钠平衡的作用

验证了单宁酸能引起植食性哺乳动物钠平衡的假设.在两种食物蛋白质水平条件下,测定了摄食含0%,3%和6%单宁酸食物的根田鼠的钠平衡和肾上腺肾小球的大小.结果表明,食物单宁酸能显著影响根田鼠的钠平衡,钠的丢失主要通过尿液.同时,单宁酸能显著影响试验个体的肾上腺肾小球的体积.初步研究显示,植食性哺乳动物对摄入的植物次生化合物的解毒引起机体钠平衡失调,而非植物次生化合物的消化抑制作用所致.     

Dietary sodium alginate administration affects fingerling growth and resistance to Streptococcus sp. and iridovirus, and juvenile non-specific immune responses of the orange-spotted grouper, Epinephelus coioides

The percent weight gain (PWG) and feeding efficiency (FE) of fingerling orange-spotted grouper, Epinephelus coioides, fed diets containing sodium alginate at 1.0 and 2.0 g kg(-1) were calculated on the 2nd, 4th, 6th, and 8th weeks after feeding. Survival rates of the fingerling grouper against Streptococcus sp. and an iridovirus, and non-specific immune parameters such as alternative complement activity (ACH50), lysozyme activity, natural haemagglutination activity, respiratory bursts, superoxide dismutase (SOD) activity, and phagocytic activity of juvenile grouper were also determined when the fish were fed diets containing sodium alginate at 0.5, 1.0, or 2.0 g kg(-1). The PWG and FE of fish were better when the fish were fed diets containing sodium alginate at 1.0, and 1.0 and 2.0 g kg(-1), respectively. The PWG and FE of fish fed the 0, 1.0 and 2.0 g kg(-1) sodium alginate-containing diets after 8 weeks were 271.0%, 454.4% and 327.8%, and 0.61, 0.72 and 0.68, respectively. Fish fed a diet containing sodium alginate at the level of 2.0 g kg(-1) had a significantly higher survival rate than those fed the control diet after challenge with Streptococcus sp. and an iridovirus causing an increase of survival rate by 25.0% and 16.7%, respectively, compared to the control group. The ACH(50) level of fish fed the sodium alginate-containing diets at 2.0 g kg(-1) was significantly higher than those fed the 1.0 g kg(-1) sodium alginate diet and control diet after 12 days, and had increased to 1.9-fold, compared to those fed the control diet. The lysozyme activity, phagocytic activity, respiratory bursts, and SOD level of fish fed the sodium alginate-containing diets at 1.0 and 2.0 g kg(-1) were significantly higher than those fed the control diet after 12 days, and had increased to 1.97- and 1.68-fold, 1.35- and 1.50-fold, 1.63- and 1.81-fold, and 1.23- and 1.31-fold, respectively, compared to those fed the control diet. We therefore recommend dietary sodium alginate administration at 1.0 and 2.0 g kg(-1), respectively, to promote growth and enhance immunity and resistance against Streptococcus sp. and an iridovirus.     

Evaluation of Magadi soda-treated sorghum grain for young broilers

Magadi soda (MS) is a commercially available form of sodium sesquicarbonate in Kenya. Soaking high-tannin sorghum (HTS) grain (2.5% catechin equivalents) in a 6 g l⁻¹ MS solution was shown to eliminate measurable tannin content. A feeding trial was conducted to investigate the performance of broiler chicks fed soyabean-based diets containing HTS or MS-treated HTS as the sole cereal source from 1-3 weeks of age. A third diet containing sorghum with no detectable tannin content served as the control. Diets containing 220 g kg⁻¹ crude protein were fed to 6 pens of 5 birds per pen for each treatment from 1-2 weeks of age and to 4 pens of 4 birds per pen per treatment in weeks 2-3. Feed intake, weight gain and feed efficiency (FE) were determined weekly. Apparent dry matter digestibility (DMD), metabolizable energy (AMEn) and nitrogen retention (NR) were measured over the last 3 days of each period. Gain and feed intake were not affected by treatment (P > 0.05), but FE and DMD were lower (P < 0.05) for the HTS diet than for the MS-treated HTS and control diets, which themselves were similar. Absolute NR was higher (P < 0.05) for the control diet than either of the HTS diets in week 2 but was the same for all diets in week 3. As % of intake, NR was higher (P < 0.05) for the control in both weeks 2 and 3 than for the HTS diets, although this was improved (P < 0.05) by MS treatment in week 2. AMEn values showed a similar pattern to that for NR in week 2 but in week 3 was the same for the MS-treated HTS and control diets, which were higher than the HTS diet (P < 0.05). Though total tannin content did not influence growth of birds in this study, MS treatment of HTS did reduce deleterious effects on FE, AMEn and NR as a % of intake.     

Effects of potassium on expression of renal sodium transporters in salt-sensitive hypertensive rats induced by uninephrectomy

Dietary potassium is an important modulator of systemic blood pressure (BP). The purpose of this study was to determine whether dietary potassium is associated with an altered abundance of major renal sodium transporters that may contribute to the modulation of systemic BP. A unilateral nephrectomy (uNx) was performed in male Sprague-Dawley rats, and the rats were fed a normal-salt diet (0.3% NaCl) for 4 wk. Thereafter, the rats were fed a high-salt (HS) diet (3% NaCl) for the entire experimental period. The potassium-repleted (HS+KCl) group was given a mixed solution of 1% KCl as a substitute for drinking water. We examined the changes in the abundance of major renal sodium transporters and the expression of mRNA of With-No-Lysine (WNK) kinases sequentially at 1 and 3 wk. The systolic BP of the HS+KCl group was decreased compared with the HS group (140.3 ± 2.97 vs. 150.9 ± 4.04 mmHg at 1 wk; 180.3 ± 1.76 vs. 207.7 ± 6.21 mmHg at 3 wk). The protein abundances of type 3 Na(+)/H(+) exchanger (NHE3) and Na(+)-Cl(-) cotransporter (NCC) in the HS+KCl group were significantly decreased (53 and 45% of the HS group at 1 wk, respectively; 19 and 8% of HS group at 3 wk). WNK4 mRNA expression was significantly increased in the HS+KCl group (1.4-fold of control at 1 wk and 1.9-fold of control at 3 wk). The downregulation of NHE3 and NCC may contribute to the BP-attenuating effect of dietary potassium associated with increased urinary sodium excretion.     

The influence of dietary sodium on bone development in growing rats

The present study investigated the effects of dietary sodium on bone growth in young rats. Five-week-old rats were fed one of three different diets for 60 days: low sodium (NaCl, 0.32 g/kg diet), normal sodium (NaCl, 2.6 g/kg) and high sodium (NaCl, 20 g/kg). The proximal tibial metaphysis (PTM), the fifth lumbar vertebra (LV₅) and the middle part of the tibia shaft (TX) were analysed by bone histomorphometry. The expression of three osteogenesis genes, Runx2, osteopontin and osteocalcin, was determined by RT-PCR in bone samples from the skull. In both the PTM and LV₅, trabecular area and thickness were increased by the low-sodium diet, while the high-sodium diet decreased trabecular area in LV₅. Dynamic data revealed that sodium restriction increased bone formation parameters in the PTM and LV₅, but decreased bone resorption in LV₅. In TX, endosteal bone formation was enhanced by the low-sodium diet and depressed by the high-sodium diet compared to the normal sodium group. But there were no statistically changes in the cortical bone area of TX. Low-sodium intake significantly enhanced the expression of all three osteogenesis genes compared to the normal sodium group, while high-sodium intake suppressed osteogenic gene expression. Our results suggest that sodium restriction in growing rats promotes bone development by influencing both bone formation and resorption.     

Prenatal and early postnatal dietary sodium restriction sensitizes the adult rat to amphetamines

Acute sodium deficiency sensitizes adult rats to psychomotor effects of amphetamine. This study determined whether prenatal and early life manipulation of dietary sodium sensitized adult offspring to psychomotor effects of amphetamine (1 or 3 mg/kg ip) in two strains of rats. Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) dams were fed chow containing low NaCl (0.12%; LN), normal NaCl (1%; NN), or high NaCl (4%; HN) throughout breeding, gestation, and lactation. Male offspring were maintained on the test diet for an additional 3 wk postweaning and then fed standard chow thereafter until testing began. Overall, blood pressure (BP), total fluid intake, salt preference, and adrenal gland weight were greater in SHR than in WKY. WKY LN offspring had greater water intake and adrenal gland weight than did WKY NN and HN offspring, whereas WKY HN offspring had increased BP, salt intake, and salt preference compared with other WKY offspring. SHR HN offspring also had increased BP compared with other SHR offspring; all other measures were similar for SHR offspring. The low-dose amphetamine increased locomotor and stereotypical behavior compared with baseline and saline injection in both WKY and SHR offspring. Dietary sodium history affected the rats' psychomotor response to the higher dose of amphetamine. Injections of 3 mg/kg amphetamine in both strains produced significantly more behavioral activity in the LN offspring than in NN and HN offspring. These results show that early life experience with low-sodium diets produce long-term changes in adult rats' behavioral responses to amphetamine.     

The replacement of skim milk by dried microbial cells and whey in milk diets for calves

In two experiments, the performance and health of calves fed on diets containing dried microbial cells (DMC) was monitored. In the first experiment 32 seven-day-old British Friesian bull calves, reared on a conventional early weaning system to 8 weeks of age, were given milk replacers in which 5, 10 and 20% spray-dried DMC and whey replaced 14–55% of skim milk protein. All DMC diets contained 36 g/kg of non-nucleic acid nitrogen. In Experiment 2, 38 two-day-old Ayrshire bull calves were fed for 63 days solely on one of two milk diets containing 0 or 10% DMC at 5 levels of intake designed to produce body gains of 0–1 kg/day. While the inclusion of up to 10% DMC in both experiments had little effect on performance or health, 20% DMC was associated with severe diarrhoea, loss of appetite and growth retardation, and impaired clotting of the milk in vitro. In Experiment 2 the response, in gain, by calves given increasing intakes of milk dry matter was linear and was unaffected by the type of diet offered.It was concluded that when levels of DMC in excess of 10% inclusion are used in association with maize starch, deleterious effects on performance are likely.     

Effects of inclusion level and source of dietary sodium on performance and meat characteristics of broiler chickens

The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO3 and Na2SO4) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCI and Na2SO4) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1-14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO3, Na2SO4 seemed to be a better alternative for NaCl. Na2SO4 also tended to surpass NaHCO3 as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.     

Reciprocal combinations of alfalfa hay and corn silage in the starter diets of Holstein dairy calves: effects on growth performance,nutrient digestibility,rumen fermentation and selected blood metabolites

Adding corn silage (CS) instead of alfalfa hay (AH) to the finely ground starter diet would improve calf performance if feed intake or feed efficiency is increased. We investigated the effects of replacing AH with CS in the starter diet on nutrient intake, digestibility, growth performance, rumen fermentation and selected blood metabolites in Holstein calves. Newborn male calves (n = 30; 3 days of age; 40.2 ± 1.28 kg BW) were assigned randomly to three groups receiving starter diets containing chopped AH (10% dry matter (DM) basis; AH diet), CS (10% DM, CS diet) or their combination (each at 5% level; AHCS diet). The starter diets had the same nutrient composition but differed in DM content (91.2%, 87.5% and 83.8% for AH, AHCS and CS, respectively). The calves were weaned on day 50, and the study continued until day 70. Nutrient intake, BW (at weaning and at the end of the study) and body measurements were not affected by the diet. During the post-weaning period, average daily gain tended to be greater on CS than on AH diet. Feed efficiency was greater in CS than in AH or AHCS calves during the post-weaning period. Digestibility of neutral detergent fiber was greater in AHCS and CS compared with AH during the post-weaning period. Concentration and profile of volatile fatty acids and ruminal fluid pH were not affected by the diet. Replacing AH with CS in the starter diet had no effect on feed intake, growth performance and general health of the calves. These results indicate that AH and CS can be used interchangeably in dairy calf starter diets until 70 days of age, allowing dairy producers more choices in selecting the feed ingredients.     

Quantitative autoradiography demonstrates selective modulation of rat brain regional dopamine (D1 and D2) receptor subtypes after chronic manipulation of dietary salt

The effects of chronic dietary sodium chloride (NaCl) consumption on renal function and brain dopamine receptors were studied in adult, male normotensive rats. Compared to rats maintained on the normal NaCl (0.33%) diet, animals maintained on the low NaCl (0%) diet for 4 weeks exhibited significant increases in plasma aldosterone, chloride and changes in urinary electrolyte excretion. In contrast, rats maintained on the high NaCl (8%) diet for 4 weeks demonstrated significant increases in urine volume and urinary sodium, chloride and dopamine excretions and water intake. Rats fed the high NaCl diet displayed a 42–59% decrease (p<0.001–0.05) in D₁ binding in the nucleus accumbens (NA), olfactory tubercle (OT) and the striatum (STM), without any effects on D₂ binding in these brain regions. Rats maintained on the low NaCl diet also demonstrated decreased D₁ binding in the ventral (24%, p<0.02) and lateral (29%, p<0.01) STM, but not in the OT, NA, entopeduncular nucleus and substantia nigra. Rats fed low or high NaCl diets exhibited a 35–180% increase (p<0.01–0.05) in D₂ binding in several mid-brain areas (e.g. hypothalamus, thalamus and hippocampus) and hindbrain regions (e.g. superior colliculus and nucleus tractus solitarius) without affecting the D₁ binding. These data indicate that chronic modification of dietary salt intake profoundly affects the renal handling of sodium/water excretion and leads to selective up- and/or down-regulation of DA receptor subtypes in different areas of the brain. These findings may have relevance to centrally-mediated hypertension, Parkinson's disease, schizophrenia and other brain disorders involving dopamine and dopamine receptors.     

Dietary self-selection for organic acids by the piglet

Two feeding trials using 48 weaned crossbred piglets each were carried out to determine the effect of acidifying diets with potassium diformate (K-diformate), formic or sorbic acid on dietary preferences in piglets. In Exp. 1 two reference groups were fed either an unacidified diet or a diet containing 2.4% of K-diformate with no choice for selection. Furthermore, piglets in choice group 1 and 2 had the choice between an unacidified diet and a diet supplemented with 1.2 and 2.4% K-diformate, respectively. In Exp. 2, animals of three reference groups received exclusively an unacidified diet or diets supplemented with 1.2% formic acid or 1.2% sorbic acid, respectively. The animals of the choice groups had the choice between an unacidified diet and diets with 1.2% formic acid or 1.2% sorbic acid, respectively. In Exp. 1 average daily feed intake, daily gain and feed conversion ratio were 751?g, 458?g and 1.64?kg/kg, respectively, with no significant differences between treatments. In both choice feeding groups animals chose the diets on offer at random (each around 50%). In Exp. 2 growth and feed intake were not affected by the treatment, but feed conversion ratio was enhanced due to the 1.2% formic acid supplementation. Animals of both organic acid choice groups showed a significant preference for the unacidified diets in each experimental week. The formic acid and sorbic acid diets represented on average only 13.5% and 23.5% of the total feed intake. The present results demonstrate that the inclusion of 1.2% sorbic or formic acid or 2.4% of K-diformate in piglet diets has no negative impact on feed intake, but in a situation of choice feeding, piglets will refuse diets acidified with 1.2% formic or sorbic acid, presumably because of negative taste cues. Acidifying the diets with varying amounts of a K-diformate had no effect on dietary preferences of piglets.     

Dietary self-selection for organic acids by the piglet

Two feeding trials using 48 weaned crossbred piglets each were carried out to determine the effect of acidifying diets with potassium diformate (K-diformate), formic or sorbic acid on dietary preferences in piglets. In Exp. 1 two reference groups were fed either an unacidified diet or a diet containing 2.4% of K-diformate with no choice for selection. Furthermore, piglets in choice group 1 and 2 had the choice between an unacidified diet and a diet supplemented with 1.2 and 2.4% K-diformate, respectively. In Exp. 2, animals of three reference groups received exclusively an unacidified diet or diets supplemented with 1.2% formic acid or 1.2% sorbic acid, respectively. The animals of the choice groups had the choice between an unacidified diet and diets with 1.2% formic acid or 1.2% sorbic acid, respectively. In Exp. 1 average daily feed intake, daily gain and feed conversion ratio were 751 g, 458 g and 1.64 kg/kg, respectively, with no significant differences between treatments. In both choice feeding groups animals chose the diets on offer at random (each around 50%). In Exp. 2 growth and feed intake were not affected by the treatment, but feed conversion ratio was enhanced due to the 1.2% formic acid supplementation. Animals of both organic acid choice groups showed a significant preference for the unacidified diets in each experimental week. The formic acid and sorbic acid diets represented on average only 13.5% and 23.5% of the total feed intake. The present results demonstrate that the inclusion of 1.2% sorbic or formic acid or 2.4% of K-diformate in piglet diets has no negative impact on feed intake, but in a situation of choice feeding, piglets will refuse diets acidified with 1.2% formic or sorbic acid, presumably because of negative taste cues. Acidifying the diets with varying amounts of a K-diformate had no effect on dietary preferences of piglets.