Intermediate Diet Research Articles

Use of radiocarbon to estimate diet ages of earthworms across different climate regions

Natural abundance of radiocarbon (14C) has been applied to estimate the turnover time of soil carbon (C) across different climate regions. However, despite the important functional role played by soil animals in decomposition processes, little is known about variation in their 14C concentrations across different climate regions. In this study, we measured 14C concentrations of earthworms collected in three forests in Japan. In addition, we also reviewed 14C data on earthworms that were previously reported. We used these data to test whether the diet ages (defined as time elapsed since C in the diet of earthworms was fixed from atmospheric CO2 by photosynthesis) differed according to feeding habits and across study sites in various climate regions ranging from cool temperate forest to tropical savanna. Multiple regression analysis showed that the diet ages of earthworms were significantly affected by both feeding habits and study sites. The diet ages of endogeic (soil-feeding) earthworms (8.3±0.4 years, mean±SE) were significantly older than those of epigeic (litter-feeding) earthworms (2.6±0.5 years), with anecic (litter-/soil-feeding) earthworms (5.7±0.9 years) having intermediate diet ages. When mean diet age was compared for each feeding habit, only that of endogeic earthworms differed significantly across the sites. However, it did not necessarily become younger in warmer climate regions. These results either suggest that the degree of decomposition of soil organic matter used by earthworms differs among the study sites, or that the difference in the turnover time of soil organic C used by earthworms across the sites is relatively small and variable due to factors other than temperature, such as soil texture and vegetation.

Historical distribution, habitat requirements and feeding ecology of the genus Equus (Perissodactyla)

Abstract Dietary traits of nine extant Equus species (E. africanus, E. ferus, E. grevyi, E. hartmannae, E. hemionus, E. khur, E. kiang, E. quagga and E. zebra) were reconstructed and ranked in a continuum reflecting the relative proportions of abrasion and attrition. In order to match them automatically with climatic data, localities were referenced within a 2° worldwide grid system using geographical information system software. The mesowear score was used as a proxy variable to test the covariance of diet with mean annual precipitation, evapotranspiration, mean annual climatic water balance and mean annual temperature. Seven of the nine equid species presented mesowear signatures indicating a grass‐dominated diet, and we found interspecific as well as intraspecific variability. Non‐gramineous food components shifted the equilibrium towards the attrition‐dominated end in E. africanus and E. khur, indicating an intermediate diet. Especially in E. zebra, additional sources of exogenous abrasives (grit and soil) might increase dietary abrasiveness. In E. quagga, dietary flexibility and the capability to cope with increased abrasiveness are considered keystone factors allowing its large geographical range. The broad, species‐specific range of climate parameters associated with the habitats was used to define the thresholds of the species' feeding niches. Our data suggest that climate as represented by the variables we used does not, in the first instance, relate to the tooth wear signature of equids. We thus conclude that the tooth wear signature is more specific to the feeding strategy and should be regarded a dietary trait rather than an immediate imprint of climate. However, tooth wear can be used to infer local dietary traits and might therefore become an important tool in conservation management.

Differences in Dietary Patterns among Haitian and African Americans with and without Type 2 Diabetes

The study investigated differences in dietary patterns measured with the Healthy Eating Index (HEI) and the Alternate Healthy Eating Index (AHEI) in African Americans (AA) and Haitian Americans (HA) with and without type 2 diabetes (T2D). A cross‐sectional study conducted in AA (n=225) and HA (n=246). Participants were recruited from multiple sources from Miami‐Dade and Broward Counties, Florida. Demographic, anthropometric and lifestyle data were collected. Dietary variables were collected using a food frequency questionnaire and the HEI and the AHEI scores were calculated. T‐test, chi‐square and multinomial regressions were used for analysis. HA had a significantly higher AHEI scores (p=.001) compared to AA (p =.001). HEI scores were significantly higher for HA compared to AA (p=.001). AA were 3.6 times more likely than HA to have an intermediate diet adherence (p<.001) and 12 times more likely than HA to have a low diet adherence in the AHEI dietary pattern (p<.001). In the HEI dietary pattern, AA were 2.4 times more likely than HA to have an intermediate diet adherence (p<.001) and 5.2 times more likely than HA to have a low diet adherence (p<.001). Ethnicity is a commonly overlooked dimension of the heterogeneity in the black population living in the US. Adequate dietary evaluation may be conducive to focused nutrition interventions. Funding for this research was provided through an NIH/NIDDK sponsored grant.

Trophic diversity of idoteids (Crustacea, Isopoda) inhabiting the Posidonia oceanica litter

The coexistence of three idoteid species in Posidonia oceanica litter raises the question of trophic diversity and their role in the litter degradation process. Hence, diet composition of Idotea balthica, Idotea hectica and Cleantis prismatica was studied using a combination of gut contents and stable isotopes analysis. Gut content observations indicate that P. oceanica dead leaves are an important part of the ingested food for the three species, although their tissues are constituted of only a small to medium fraction of P. oceanica carbon. Our results also underlined the potential role of these species in the degradation of P. oceanica litter by mechanically fragmenting the litter and by assimilating a small to medium fraction of carbon. Moreover, we showed that there were considerable inter- and intra-specific differences in diet composition. Diet differed between juveniles and adults for I. balthica. Crustaceans are an important food source for adults of I. balthica, while I. hectica indicated a major contribution of algal material. C. prismatica showed an intermediate diet. This trophic diversity is probably one of the factors allowing these species to coexist in the same biotope.

Effects of nutritional quality during early development on body weight and reproductive maturation of guinea pigs ( Cavia aperea f. porcellus)

In many species, somatic and reproductive maturation are sensitive to seasonally-fluctuating environmental conditions such as food quality. The protein content of the diet during early development has been considered to be particularly important, a low-protein diet during gestation and lactation typically delaying growth and reproductive onset. To investigate the effects of maternal and early postnatal diet quality on body weight and puberty of male and female domestic guinea pigs, we fed F0-mothers either a low-protein (14%, LQ-group) or a high-protein diet (23%, HQ-group) during gestation and lactation. Their male and female offspring received the same respective diets until six weeks of age; afterward they were switched to an intermediate control diet. Body weight of F1-subjects was significantly affected by the dietary treatment. Reproductive parameters were only affected in F1-females but not in F1-males. We conclude that in guinea pigs, growth is sensitive to the quality of the maternal and early postnatal diet, and that reproductive maturation is more sensitive in females.

Morphology–diet relationships in four killifishes (Teleostei, Cyprinodontidae,Orestias) from Lake Titicaca

This study explores the relationship between morphology and diet in four Andean killifishes (Orestias) from Lake Titicaca that are known to differ in habitat use. Species that fed preferentially on amphipods (Orestias albus) or molluscs (Orestias luteus) separated in multivariate space from other species that feed on cladocera and algae (Orestias agassii and Orestias jussiei). Generally, specimens feeding on cladocera were characterized by a short, blunt nose with a small mouth; whereas, specimens feeding on amphipods exhibited a long snout with a large mouth. Specimens including molluscs in their diet tended to have a larger posterior part of the head and the larger opercles than others; while the occurrence of substratum in gut content was generally related to a short but deep head. The present analysis suggests that the littoral O. jussiei has an intermediate phenotype and diet between the pelagic (O. agassii) and benthic (O. albus and O. luteus) species. Results suggest that resource partitioning was occurring and that several morphological traits relate to characteristics of the diet, and it is inferred that the benthic, the pelagic and the littoral zones in the lake host different prey communities constituting distinct adaptive landscapes.

Trophic links and riverine effects on food webs of pelagic fish of the north-western Black Sea

Improving the knowledge of trophodynamics in coastal marine ecosystems is important for fisheries management. The present study was designed to assess the influence of Danube River inputs on Romanian coastal marine food webs of the European sprat (Sprattus sprattus), the European anchovy (Engraulis encrasicholus) and the horse mackerel (Trachurus mediterraneus). Gut content analyses coupled with carbon and nitrogen stable isotope analyses described food web variations with fish size, season and distance from the Danube delta. Sprats fed on zooplankton, horse mackerel fed on polychaetes and small fish, and anchovies had an intermediate diet. The δ13C and δ15N ratios and mean trophic levels increased from sprats to anchovies and then to horse mackerel. Season strongly influenced the δ15N values of the three fishes, with lower values in spring than in autumn linked to higher Danube inputs into coastal waters in spring during the flooding period. Fish condition was related to diet and environmental factors, with higher conditions recorded in the north area in autumn and in the south area in spring. Danube River inputs influenced the diet, stable isotope ratios and condition of the main commercial pelagic migratory fishes of the north-western Black Sea.

Effects of Benthic Prey Composition and Abundance on Diet and Growth of Black Crappies in Three Florida Lakes

AbstractThe influence of benthic prey availability on growth of black crappies Pomoxis nigromaculatus is poorly understood due to scant research on the relationships between benthic prey abundance and composition and black crappie diet. However, benthic taxa play an important role as prey items of black crappies during intermediate ontogenetic diet phases. We evaluated diet, growth, and abundance of black crappies in three large Florida lakes (Lochloosa, Marian, and Monroe), and we related diets to benthic prey availability at these lakes. Black crappies in Lake Monroe obtained the largest size at age, whereas those in Lake Marian had the smallest size at age. Black crappies in Lakes Lochloosa and Marian consistently exhibited positive selection of dipteran pupae; fish in Lake Monroe showed consistently positive selection of a higher‐quality prey item (the mysid shrimp Americamysis almyra) that was not available in Lakes Lochloosa and Marian. A similarity index indicated that benthic prey availability influenced consumption of benthic prey items by black crappies in all three lakes. Differences in prey availability (i.e., density and presence‐absence) and prey selection influenced diet composition and ontogenetic diet shifts of black crappies. Diet and prey availability differences among lakes probably contributed to the variation in black crappie growth rates; the highest growth was observed at Lake Monroe, where the additional prey resource (A. almyra) was available.

High selenium diet protects against TNBS-induced acute inflammation, mitochondrial dysfunction, and secondary necrosis in rat colon

Objective We studied the protective effects of selenium in a rat model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)–induced colitis to elucidate a possible mechanism of action. Method Rats were supplemented with sodium selenite for 21 d with a normal selenium diet (0.02 μg/g body weight), an intermediate selenium diet (ISD; 0.3 μg/g body weight), or a high selenium diet (HSD; 2 μg/g body weight). On day 22, colitis was induced with TNBS. Rats were sacrificed after 24 h and colonic tissue was removed for evaluation. Results Selenium supplementation (HSD) resulted in a significant increase in selenium in colonic tissue. Morphologically, the HSD resulted in the preservation of tissue architecture and attenuated neutrophil infiltration; no vasculitis or necrosis was detected. Biochemically, the HSD decreased tissue myeloperoxidase activity and protected the mitochondria in the colon of TNBS-treated animals as evaluated by preserving tissue oxygen consumption, mitochondrial DNA, and expression of cytochrome c. The HSD increased levels of nuclear respiratory factor-1 and mitochondrial transcription factor-A in normal colon tissue and under inflammatory conditions. The ISD resulted in only a minor protective effect. Conclusion The results indicate that tissue damage in TNBS-induced colitis is accompanied by the arrest of mitochondrial respiration, loss of mitochondrial DNA, and the expression of nuclear-encoded mitochondrial proteins. Selenium effectively protects colon mitochondria by upregulation of the expression of mitochondrial transcription factors nuclear respiratory factor-1 and mitochondrial transcription factor-A. Selenium prevented inflammatory and necrotic changes after induction of colitis. Selenium in a high dose is therefore a potential therapeutic agent in inflammatory bowel disease.

Application of Mathematical Models to Individually Allocate Feed of Group-fed Cattle

ABSTRACT A data set of group-fed growing and finishing steers with individual feed access was used to evaluate predictions of required individual DM by 2 mathematical models (Cornell Value Discovery System, CVDS; and beef NRC) to allocate feed of group-fed, commingled cattle. Forty-eight crossbred steers (BW = 296 kg) were assigned to 1 of 6 pens and fed 1 of 4 growing diets formulated to have different energy concentrations for restricted or ad libitum intake regimen for 56 d. The diets were a low-starch diet fed ad libitum, a high-starch diet fed ad libitum, a high-starch with restricted intake, and an intermediate diet fed ad libitum with an average energy intake between ad libitum low-starch and ad libitum high starch diets. On d 57, all steers (BW = 401 kg) were placed on the ad libitum high-starch diet for finishing until d 140. The CVDS was able to account for 61% of the variation in the observed DMI (oDMI) of steers during the growing period, and for 71% of the variation in oDMI during finishing, with an average overprediction of 3.76%. In the same fashion, the NRC model was able to explain 59% of the variation in oDMI after adjustment for known performance during the growing period with no bias (P > 0.10), and 57% of the variation in oDMI during the finishing period, with an average underprediction of 4.40%. Our overall evaluation suggested that the CVDS was more precise and accurate than the NRC model when predicting DMI for individual animals. Both models were sensitive to the previous level of nutrition of the cattle, suggesting that more variables are necessary to increase the prediction precision for cattle growing systems. The results from a risk analysis suggested that an amount of approximately $17.00/animal may be either over- or under-charged in the billing process of a commercial feedlot growing and finishing periods. Therefore, mathematical models could assist commercial feed-lots to improve the accuracy of the billing process while maintaining the same income per pen.

Oceanographic and climatic factors differentially affect reproduction performance of Antarctic skuas

We studied how environmental conditions affect reproduction in sympatric skua species that differ in their reliance on marine resources: the exclusively marine foraging south polar skua Catharacta maccormicki, the terrestrially foraging brown skua C. antarctica lonnbergi and mixed species pairs with an intermediate diet. Egg size, clutch asymmetry and hatching dates varied between species and years without consistent patterns. In the south polar skuas, 12 to 38% of the variation in these parameters was explained by sea surface temperature, sea ice cover and local weather. In mixed species pairs and brown skuas, the influence of environmental factors on variation in clutch asymmetry and hatching date decreased to 10-29%, and no effect on egg size was found. Annual variation in offspring growth performance also differed between species with variable growth in chicks of south polar skuas and mixed species pairs, and almost uniform growth in brown skuas. Additionally, the dependency on oceanographic and climatic factors, especially local wind conditions, decreased from south polar skuas to brown skua chicks. Consistent in all species, off- spring were more sensitive to environmental conditions during early stages; during the late chick stage (>33 d) chick growth was almost independent of environmental conditions. The net breeding success could not be predicted by any environmental factor in any skua species, suggesting it may not be a sensitive indicator of environmental conditions. Hence, the sensitivity of skuas to environ- mental conditions varied between species, with south polar skuas being more sensitive than brown skuas, and between breeding periods, with the egg parameters being more susceptible to oceano- graphic conditions. However, during offspring development, local climatic conditions became more important. We conclude that future climate change in the Maritime Antarctic will affect reproduction of skuas more strongly through changes in sea ice cover and sea surface temperature (and the result- ing alterations to the marine food web) than through local weather conditions.

Feed allowance-genotype interactions in broiler breeder hens

Ad libitum feeding reduces livability and reproductive fitness in broiler breeder hens. Two genotypes, a standard (S) and an experimental dwarf broiler breeder (E), were fed ad libitum (SA and EA, respectively), restricted at 55% of ad libitum feed intake (intermediate restriction) from 6 to 15 wk of age (SI and EI, respectively), or restricted (SR and ER, respectively) to match a standard growth curve with a diluted mash feed (2,400 kcal/kg). The experiment was repeated at 2 locations (experiment 1 = 672 hens in pens from 0 to 40 wk; experiment 2 = 420 hens in pens and cages from 0 to 53 wk). Feed restriction reduced adult BW by 20% compared with ad libitum feeding, delayed sexual maturity by 2 to 4 wk, and improved livability. Hens fed the intermediate diet immediately compensated after 15 wk of age to reach BW, sexual maturity, and livability close to those of ad libitum-fed hens. The E genotype exhibited better tolerance to ad libitum feeding than the S genotype in all measured aspects. Average laying rate during the first 24 wk of lay was 66.4, 77.4, 69.9, 47.2, 57.9, and 72.4% for EA, EI, ER, SA, SI, and SR respectively in experiment 2. Egg abnormalities (double yolk, shell problems) decreased after the peak of lay but remained consistently higher for S compared with E, and for ad libitum and intermediate diets compared with the restricted diet. Yolk deposition rate was measured by a double dye technique. Duration of yolk rapid growth was 8.8 d in E and 9.3 d in S hens (P < 0.001), but this difference did not explain the observed variations in laying rate. The potential to increase feed allowances even with a diluted diet in broiler breeder hens requires adapted genotypes.

The influence of calcium intake on phosphorus digestibility in mature ponies

Literature data show conflicting results on the effect of feeding high calcium (Ca) levels on phosphorus (P) digestibility in ponies. None of the studies reported involved a dose response as to the effect of Ca intake on apparent P digestibility while keeping P intake constant. Thus, the influence of high dietary Ca level on apparent P digestibility was studied in balance trials by feeding six mature ponies three different Ca levels against a constant P intake. The ponies received 148, 316 and 535 mg Ca/kg BW/day with the low, intermediate and high Ca diet. Phosphorus intake was approximately 125 mg P/kg BW and magnesium (Mg) intake was approximately 35 mg Mg/kg BW/day. The intermediate and high Ca level decreased apparent digestibility, renal excretion and retention of P when compared with the low Ca level. However, apparent digestibility and renal excretion of P were not different between the intermediate and high Ca level. The high Ca level resulted in a retention of 66 mg Ca/kg BW/day. The percentage apparent digestibility of Ca was lower for the intermediate and high Ca level compared with the low Ca level. Magnesium digestibility was not affected by high dietary Ca level. In practice, high absolute amounts of Ca should be prevented especially when low amounts of P are fed; P digestibility will be depressed and a negative P balance may occur.

Hyperhomocysteinemia leads to pathological ventricular hypertrophy in normotensive rats.

A recent report indicated that hyperhomocysteinemia (Hhe), in addition to its atherothrombotic effects, exacerbates the adverse cardiac remodeling seen in response to hypertension, a powerful stimulus for pathological ventricular hypertrophy. The present study was undertaken to determine whether Hhe has a direct effect on ventricular remodeling and function in the absence of other hypertrophic stimuli. Male Wistar-Kyoto rats were fed either an amino acid-defined control diet or an intermediate Hhe-inducing diet. After 10 wk of dietary treatment, rats were subjected to echocardiographic assessment of left ventricular (LV) dimensions and systolic function. Subsequently, blood was collected for plasma homocysteine measurements, and the rats were killed for histomorphometric and biochemical assessment of cardiac remodeling and for in vitro cardiac function studies. Significant LV hypertrophy was detected by echocardiographic measurements, and in vitro results showed hypertrophy with significantly increased myocyte size in the LV and right ventricle (RV). LV and RV remodeling was characterized by a disproportionate increase in perivascular and interstitial collagen, coronary arteriolar wall thickening, and myocardial mast cell infiltration. In vitro study of LV function demonstrated abnormal diastolic function secondary to decreased compliance because the rate of relaxation did not differ between groups. LV systolic function did not vary between groups in vitro. In summary, in the absence of other hypertrophic stimuli short-term intermediate Hhe caused pathological hypertrophy and remodeling of both ventricles with diastolic dysfunction of the LV. These results demonstrate that Hhe has direct adverse effects on cardiac structure and function, which may represent a novel direct link between Hhe and cardiovascular morbidity and mortality, independent of other risk factors.

Rearing on basal or high dietary NaCl modifies chorda tympani nerve responses in rats

Two experiments were conducted to determine the influence of dietary NaCl level on the integrated responses of the chorda tympani (CT) nerve to salt stimulation alone and mixed with the sodium-channel blocker, amiloride hydrochloride. Five groups of adult male rats were reared on regular chow containing either basal 0.1%, intermediate 1.0%, or high 3.0% NaCl from conception to postnatal day (PD) 30 or from conception to adulthood. Adult rats reared from conception to adulthood on basal dietary NaCl demonstrated a reduction in the CT nerve response to NaCl due to a decrease in the amiloride sensitive transduction mechanism. However, the CT nerve responses of adult rats reared on basal dietary NaCl to PD30 and then switched to intermediate dietary NaCl were similar to those of rats reared for a lifetime on intermediate dietary NaCl. Similarly, the CT nerve responses to NaCl in animals reared on high dietary NaCl from conception to PD30 and then switched to an intermediate NaCl diet were comparable to animals reared on intermediate and basal dietary NaCl. However, we found that exposure to high dietary NaCl led to a greater amiloride inhibition of NaCl responses. Thus, there is critical association between dietary NaCl level over two different exposure periods and CT nerve responsiveness to NaCl specifically regarding the degree of amiloride inhibition.

Clustering of Endothelial Markers of Vascular Damage in Human Salt-Sensitive Hypertension

The contributing role of vascular endothelium in the development of hypertension-related vascular damage is well accepted. Salt-sensitive hypertension is characterized by a cluster of renal, hormonal, and metabolic derangements that might favor the development of cardiovascular and renal damage. To evaluate endothelial involvement in salt-sensitive essential hypertension, plasma levels of several markers of endothelial damage such as endothelin-1 (ET-1), von Willebrand factor (vWf), and soluble (S-) adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and 24-hour urinary albumin excretion (UAE) were measured in 39 nondiabetic, nonobese, never-treated essential hypertensive patients after intermediate (120 mmol/d), high (220 mmol/d), and low (20 mmol/d) NaCl diets. Patients were classified as salt sensitive (n=18) or salt resistant (n=21) according to their blood pressure responses to changes in dietary NaCl intake. Salt-sensitive hypertensives showed higher plasma ET-1 (P<0.05), vWf (P<0.005), and S-E-selectin levels (P<0.04) and increased UAE (P<0.05) than salt-resistant hypertensives. By contrast, circulating S-ICAM-1 and S-VCAM-1 concentrations were not significantly higher in salt-sensitive (596. 56+/-177.05 ng/mL and 541.06+/-157.84 ng/mL, respectively) than salt-resistant patients (516.86+/-147.99 ng/mL and 449.48+/-158.91 ng/mL, respectively). During the intermediate NaCl diet, plasma ET-1 responses to oral glucose load were greater in salt-sensitive (P<0. 05) than in salt-resistant patients. A marked (P<0.05) hyperinsulinemic response to oral glucose load was evident in salt-sensitive but not salt-resistant patients after each diet. This study shows increased plasma levels of the endothelium-derived substances E-selectin, vWf, and ET-1 in salt-sensitive hypertensives. Our findings support the hypothesis that salt sensitivity is correlated with an increased risk for developing hypertension-related cardiovascular damage.

Interactions between nutrition, testosterone and inhibin in the control of gonadotrophin secretion in mature rams

The role of negative feedback by two testicular hormones, testosterone and inhibin, in the gonadotrophin responses of mature male sheep to changes in nutrition was tested. Six days after castration, 24 Merino rams were assigned to groups that were fed either a diet that maintained their initial liveweight (Intermediate diet), or about half of the Intermediate diet (Low diet), or the Intermediate diet with a supplement of lupin grain (High diet). One week after the change of diet, all animals were given subcutaneous testosterone implants, providing plasma testosterone concentrations of 3.06 +/- 0.14 ng mL-1 (mean +/- s.e.m.; n = 24). The implants were left in place for 7 days, during which time all the rams were also injected subcutaneously with 2 mL steroid-free bovine follicular fluid (bFF) every 8 h, to provide inhibin at mean plasma concentrations of 0.40 +/- 0.04 ng mL-1 (n = 24; compared with 1.50 +/- 0.12 ng mL-1 when the animals were intact). Five days after castration, there were significant increases in the frequency of luteinizing hormone (LH) pulses (from 1.83 +/- 0.23 to 17.3 +/- 0.96 pulses per 12 h; mean +/- s.e.m.; n = 24) and concentrations of FSH (from 0.45 +/- 0.07 to 14.19 +/- 2.7 ng mL-1; n = 24). Dietary treatment did not significantly affect these responses. Treatment with bFF and testosterone for 7 days reduced LH-pulse frequencies and follicle-stimulating hormone (FSH) concentrations in all groups. The degree of reduction was least in the group on the High diet, for which the FSH concentration (6.49 +/- 1.96 ng mL-1) and frequency of LH pulses (7.00 +/- 2.31 pulses per 24 h) were significantly higher than those observed in the other groups. The mean frequency of LH pulses did not differ significantly between the Intermediate group (0.88 +/- 0.61 pulses per 24 h) and the Low group (0.25 +/- 0.25 pulses per 24 h). Similarly, FSH concentrations did not differ significantly between these two groups (1.78 +/- 0.46 for the Intermediate group v. 1.33 +/- 0.26 ng mL-1 for the Low group). It is concluded that there is no response to diet in the absence of testicular hormones and the effects of nutrition on LH secretion in castrated rams given exogenous testosterone and inhibin are similar to those observed in intact rams.

Blood and Hydrolyzed Feather Meals as Sources of Undegradable Protein in High Fat Diets for Cows in Early Lactation

Thirty-six cows were in a 2 × 3 factorial study during the first 2 mo of lactation to examine effects on milk yield and composition of added fat (5% of feed DM) and percentage of ruminally undegradable protein (100, 120, or 140% of recommended intake) in the diet. The main source of added undegradable protein was a 1:1 (wt/wt) mixture of blood meal:hydrolyzed feather meal. Diets were low in ADF (ca 14%) and were highly fermentable in the rumen. The amount of intermediate dietary protein reduced feed intake. Milk yield was high (40 to 44 kg/d), similar among treatment groups, and was sustained for the entire 60-d trial. All cows yielded milk of low fat content (2.1 to 3.2%); supplemental fat decreased proportions of C6 to C14, C18:2. and C18:3 in milk fat and increased C4, C16:0, C18:0, and C18:1. Higher dietary protein had a positive linear effect on milk fat percentage and increased C16:O and decreased trans-C18:1 and C18:2 contents of milk fat. Added fat did not change total milk N but increased NPN as a percentage of total milk N. Percentage of total N in milk and yield of whey N was reduced when the intermediate protein diet was fed, associated with the lower DMI of this diet. A requirement for ruminally undegradable protein intake higher than recommended by NRC was not demonstrated with the highly fermentable diets fed in this study; however, ruminal acetate: propionate ratio and milk fat percentage were low.

Effects of nutrition on testicular size and the concentrations of gonadotrophins, testosterone and inhibin in plasma of mature male sheep.

The effects of nutrition on the hypothalamo-pituitary-gonadal axis were studied in three groups of six mature Merino rams that were fed for 56 days with a ration that maintained their initial live mass (intermediate diet: 675 g chaff plus 175 g lupins), the same ration with a lupin supplement (high diet: 675 g chaff plus 825 g lupins), or about half of the intermediate ration (low diet: 475 g chaff plus 125 g lupins). Lupin seed provides a highly (95%) digestible source of energy and protein. Plasma concentrations of LH, FSH, testosterone and inhibin were measured in blood samples collected over 24 h on the day before dietary treatments began (day-1), then on days 0, 1, 5, 14, 28 and 56. Compared with the intermediate diet, the high diet significantly increased live mass within 14 days and testicular size within 28 days, and these differences increased steadily throughout the experiment. Plasma FSH concentrations and LH pulse frequency increased within 5 days, but these effects were maintained for only 14 days. Decreasing the nutritional status reduced live mass and testicular size within 7 days, led to a low LH pulse frequency that persisted throughout the experiment, but did not affect FSH concentrations. Significantly less testosterone was secreted over 24 h in the low dietary group than in the intermediate or high group until day 28. The high group tended to secrete more than the intermediate group, but only at the beginning of the experiment when LH pulse frequencies differed between these groups.(ABSTRACT TRUNCATED AT 250 WORDS)

High NaCl intake of rat dams alters maternal behavior and elevates blood pressure of adult offspring

The present study investigated whether differences in maternal NaCl intake altered 1) maternal-pup behavior and 2) the development of dietary obesity and blood pressure level of adult Sprague-Dawley rats maintained on a palatable high-fat/milk (HF/M) diet. Thirteen dams fed high (3%) NaCl and 12 dams fed basal (0.12%) NaCl were observed on postnatal days 2-21 for differences in the number of times spent 1) nursing, 2) in contact with or licking, sniffing, and carrying pups, and 3) in nest building. The offspring were continued on their respective NaCl diets to 30 days postpartum, and then both NaCl groups were fed an intermediate (1%) NaCl diet thereafter. Beginning at 60 days of age, the offspring from each maternal NaCl condition were fed either Agway R-M-H 1000 pelleted food or a HF/M diet for 14 wk. Dams fed 3% NaCl spent significantly more time licking their pups than did dams fed 0.12% NaCl. The adult offspring of dams fed 3% NaCl had a significantly higher level of systolic blood pressure and consumed more calories of sweetened condensed milk on the HF/M diet than did rats raised on 0.12% NaCl. Dietary-induced obesity did not magnify the increase in systolic blood pressure from high maternal NaCl intake. The present results raise the possibility that increased maternal licking may contribute to the increased blood pressure and solution intake that follows from high maternal NaCl intake.