PF Diet Research Articles

Chocolate Byproducts and Protected Fats Enriched with Chromium to Replace Corn in Diets of Early Lactation Holstein Cows: Feed Utilization, Blood Profile, and Lactational Performance

Abstract The present experiment aimed to evaluate the partial replacement of corn with chocolate byproducts or protected fats in the diet of lactating cows on feed utilization, blood profile, and lactation performance. Fifty multiparous Holstein cows (560±22 kg BW, 3±1 parity, 7±1 days in milk, and previous milk production of 34±3 kg/d), were randomly assigned to 5 treatments in a completely randomized design for 90 days. The control diet contained a concentrate feed mixture containing (per kg DM) 412 g concentrate feed mixture, 412 g corn silage, and 176 g berseem hay. The control diet contained 17.6% crushed corn (DM basis). In another treatment, the control diet was supplemented with 1 g chromium daily (Chromium diet). In the other diets, each kg of crushed corn grain was replaced with 600 g chocolate byproducts (CH diet), 400 g protected fats (PF diet), or 500 g of chocolate byproducts and protected fats mixture (1:1 DM basis) (CHPF diet), DM basis, and each of the diets was also supplemented with 1 g chromium daily. Both amounts of protected fats and chocolate byproducts had the same energy concentration as 1 kg of corn. Without affecting feed intake, the replacement increased (P<0.01) milk production, milk fat concentration, and feed efficiency. The replacement (P<0.05) increased the concentrations of plasma total proteins, albumin, glucose, cholesterol, triglyceride, and chromium in comparison with the control diet. Higher (P<0.001) nutrient digestibility was observed with CH, PF, and CHPF treatments. It is concluded that chromium supplementation did not affect feed utilization or cows’ performance; however, partial replacement of corn with chromium supplemented protected fat, chocolate byproducts or their mixture improved milk production and feed efficiency.

Enrichment of chocolate byproducts and protected fats with zinc to partially replace corn in diets of early lactation Holstein cows

Abstract The present experiment aimed to evaluate the effect of partial replacement of corn with chocolate byproducts, protected fats, or their mixture supplemented with zinc in the diet of lactating cows on feed utilization and lactation performance for 90 days. Fifty multiparous Holstein cows (565±25 kg BW, 3±1 parity, 7±1 days in milk, and a previous milk production of 35±2.9 kg/d), were randomly assigned to 5 treatments in a completely randomized design. The control diet contained (per kg DM): 412 g concentrate feed mixture, 412 g corn silage, and 176 g berseem hay. The control diet was supplemented with 1 g of zinc daily (Zinc diet). In the other diets, each kg of crushed corn grain was replaced with (DM basis) 600 g chocolate byproducts (CH diet), 400 g protected fats (PF diet), or 500 g of chocolate byproducts and protected fats mixture (1:1 DM basis) (CHPF diet). Both amounts of protected fats and chocolate byproducts had the same energy concentration as 1 kg of corn. The total mixed ration was prepared and distributed using a horizontal mixer system after mixing for 20 min. Chemical analysis showed that the replacement minimally affected the composition of the total mixed rations. Additionally, treatments did not affect feed intake. Compared to the control treatment, the zinc treatment did not affect milk production, milk composition, or feed efficiency. Increased (P<0.05) daily production of milk and component yields, and feed efficiency as well as fat concentration were observed by the CH, PF and CHPF treatments. Without affecting other measured blood parameters or hematocrit, treatments increased (P<0.05) the concentrations of total proteins, albumin, glucose, cholesterol, triglyceride, and zinc in the blood of cows. Additionally, the CH, PF, and CHPF treatments increased (P<0.01) the digestibility of nutrients compared to the control treatment. It is concluded that the addition of zinc to the control did not affect cow performance; however, its addition to chocolate byproducts, protected fats, or their mixture to partially replace corn improved the performance of cows.

Sea lettuce (Ulva lactuca) meal combined with soybean meal in a low fishmeal diet enhanced the growth and feed intake of cultured golden rabbitfish (Siganus guttatus) during the nursery stage

A preliminary feeding trial was conducted to evaluate the effect of utilizing a high level of sea lettuce (SL), Ulva lactuca meal, as a dietary ingredient on the growth and biochemical composition of the golden rabbitfish, Siganus guttatus. Two treatments included one diet containing high SL meal combined with soybean (PP) and another diet that used fish meal as the primary protein source (FM). Golden rabbitfish were stocked into 8 of 120 L fiberglass tanks with a density of 20 fish/tank and fed for 15 weeks. The weight gain of the fish-fed PP diet was 453% higher than those provided with FM (343%). Similarly, the SGR of fish fed the PP diet was higher (1.40 %/d) compared to the PF diet (1.22 %/d). The FCR of the FM diet was lower (1.3) compared to the PP diet (1.6). Fish fed the FM diet contained a higher ash content than those fed the PP diet (14.9 vs 10.1%). Crude protein content in body fish was relatively similar for both diets. Including sea lettuce meal at 30% combined with a high level of soybean meal in a low fishmeal diet, they produced better growth performances of rabbitfish during the nursery stage.

The Impact of Fetal Programming in Ewe Nutrition with Chromium Propionate or Calcium Salts of Palm Oil on the Meat Quality and Bone of the Progeny.

This study aimed to evaluate the inclusion of chromium propionate or calcium salts of palm oil in ewes' diet during the final third of gestation and lactation on progeny performance, carcass characteristics, non-carcass components, and bone density. Forty-three ewe, Santa Inês and Dorper breed, three ± one-year-old, and body weight 57 ± 10 kg were used. The experimental design was in casual blocks in three treatments, CTL treatment (n = 15) with starch from corn; CR (n = 15) diet CTL plus chromium propionate; PF (n = 13) diet CTL plus calcium salts of palm oil. After weaning, 23 male lambs from these ewes were confined in individual stalls, with the same diet for 60days, slaughtered. The data were analyzed using the SAS program, PROC GLM, and compared the means using Tukey's test at 5% probability. The maternal diet did not alter the dry matter intake, feeding efficiency, and average daily weight gain. Therefore, weights (weaning and slaughter) and carcass yield were higher for CR and PF groups than for CTL (P < 0.05). The treatment did not influence the loin eye area and fat thickness (P > 0.05). The spleen and the respiratory tract were smaller for PF and larger for CTL (P < 0.05). Leg weight was higher for CR. The perimeter and depth of the shank for the CR and PF lambs were higher, indicating an effect of maternal nutrition in this commercial cut. The CR group had a smaller epiphysis measurement and femur length than the CTL group. We concluded that the fetal programming effect in ewes fed with Cr propionate and Ca salts of palm oil benefited the progeny by increasing their body weight, better carcass yield, and a higher proportion of prime cuts.

Association of Success in Interspecific Rearing of Nestlings with the Width of Trophic Niche of the Recipient Species in Hollow-Nesting Birds

The structure of the diet of passerine bird nestlings was analyzed in order to identify possible ways to reduce food competition between these species during the breeding period. We assumed that analysis of the effects of obtaining diets of heterospecific birds by nestlings in nature can help better understand their species-specific adaptations to living conditions, and we considered the case of joint nesting of the coal tit (Periparus ater (L. 1758)) (CT) and pied flycatcher (Ficedula hypoleuca (Pallas 1764)) (PF) in Moscow oblast as a key link. A PF male attracted a female to an artificial nest box, which has been already occupied by a CT pair. The females of both species incubated a mixed clutch sitting side by side. The CT nestlings hatched earlier than the PF nestlings, and the parents of both species began to feed them. The CT nestlings started to die one by one on the 4th day of joint feeding, and the last nestling died on the 11th day. This case encouraged us to compare the diets of nestlings from 22 broods of CTs and PFs in the same region. To compare the ratios of nestlings, we collected the portions of food that were delivered to nestlings by their parents and analyzed video recordings from the nests. The diet of PF nestlings was significantly more diverse than in CT nestlings (Berger–Parker reverse indices (1/d) were 3.01 and 2.11, respectively). Caterpillars and spiders (objects with a high content of carotenoids and taurine important for the development of nestlings) dominated in the CT diet. In PF feed, these objects occupied a much smaller portion. In addition to the above, compared with coal tits, PFs brought the following to nestlings: a significant number of objects with rough, highly chitinized covers (Coleoptera, Homoptera, etc.); objects with a sharp taste, such as true bugs (Heteroptera), ladybirds (Coleoptera, Coccinellidae), and millipedes (Diplopoda, Julidae); insects containing cantharidin toxin (soldier beetles, Coleoptera, Cantharidae). The nestlings developed successfully in PF nests to which parents brought such feed objects. The dimensional ranges of objects in the CT and PF diets completely overlapped. According to our opinion, the rougher, highly chitinized food and some poisonous insects (Cantharidae) in the PF diet make fundamentally important differences in the nutrition of PFs and CTs. Most likely, PFs have resistance to cantharidin and some other toxins that are contained in insects and therefore have a wider trophic niche.

Dietary pea fiber increases diversity of colonic methanogens of pigs with a shift from Methanobrevibacter to Methanomassiliicoccus-like genus and change in numbers of three hydrogenotrophs

BackgroundPea fiber (PF) is a potential fibrous supplement in swine production. The influence of dietary PF on microbial community in the colon of pigs remains largely unexplored. Methanogens in the hindgut of monogastric animals play important roles in degradation of dietary fibers and efficient removal of microbial metabolic end product H2. Understanding the impact of dietary PF on the structure of colonic methanogens may help understand the mechanisms of microbe-mediated physiological functions of PF. This study investigated the influence of PF on the diversity and quantity and/or activity of colonic methanongens of piglets and finishing pigs. Four archaeal 16S rRNA clone libraries were constructed for piglets and finishers fed with control (Piglet-C and Finisher-C) or PF diet (Piglet-P and Finisher-P).ResultsThere were 195, 190, 194 and 196 clones obtained from the library Piglet-C, Piglet-P, Finisher-C and Finisher-P, respectively, with corresponding 12, 11, 11 and 16 OTUs (operational taxonomic units). Significant differences of Shannon Index among the four libraries were found (P < 0.05). Libshuff analysis showed that the archaeal community structure among the four libraries were significantly different (P < 0.0001). The predominant methanogens shifted from Methanobrevibacter to Methanobrevibacter and Methanomassiliicoccus-like genus as a result of dietary PF. Supplementation of PF significantly increased the copy numbers of mcrA and dsrA genes (P < 0.05).ConclusionsAlteration of methanogenic community structure may lead to functional transition from utilization of H2/CO2 to employment of both H2/CO2 and methanol/CO2. Quantification of three functional genes (mcrA, dsrA and fhs) of methanogens, sulfate-reducing bacteria (SRB) and acetogens revealed that dietary PF also increased the activity of methanogens and SRB,probably associated with increased proportion of Methanomassiliicoccus luminyensis-species. Further study is required to examine the interaction between specific methanogens and SRB during fermentation of dietary PF.

Programming rumen bacterial communities in newborn Merino lambs

Establishment of the rumen microbiome can be affected by both early-life dietary measures and rumen microbial inoculation. This study used a 2×3 factorial design to evaluate the effects of inclusion of dietary fat type and the effects of rumen inoculum from different sources on ruminal bacterial communities present in early stages of the lambs’ life. Two different diets were fed ad libitum to 36 pregnant ewes (and their lambs) from 1 month pre-lambing until weaning. Diets consisted of chaffed lucerne and cereal hay and 4% molasses, with either 4% distilled coconut oil (CO) provided as a source of rumen-active fat or 4% Megalac® provided as a source of rumen-protected fat (PF). One of three inoculums was introduced orally to all lambs, being either (1) rumen fluid from donor ewes fed the PF diet; (2) rumen fluid from donor ewes fed CO; or (3) a control treatment of MilliQ-water. After weaning at 3 months of age, each of the six lamb treatment groups were grazed in spatially separated paddocks. Rumen bacterial populations of ewes and lambs were characterised using 454 amplicon pyrosequencing of the V3/V4 regions of the 16S rRNA gene. Species richness and biodiversity of the bacterial communities were found to be affected by the diet in ewes and lambs and by inoculation treatment of the lambs. Principal coordinate analysis and analysis of similarity (ANOSIM) showed between diet differences in bacterial community groups existed in ewes and differential bacterial clusters occurred in lambs due to both diet and neonatal inoculation. Diet and rumen inoculation acted together to clearly differentiate the bacterial communities through to weaning, however the microbiome effects of these initial early life interventions diminished with time so that rumen bacterial communities showed greater similarity 2 months after weaning. These results demonstrate that ruminal bacterial communities of newborn lambs can be altered by modifying the diet of their mothers. Moreover, the rumen microbiome of lambs can be changed by diet while they are suckling or by inoculating their rumen, and resulting changes in the rumen bacterial microbiome can persist beyond weaning.

The oral [(13)C]bicarbonate technique for measurement of short-term energy expenditure of sled dogs and their physiological response to diets with different fat:carbohydrate ratios.

The oral [(13)C]bicarbonate technique (o(13)CBT) was assessed for the determination of short-term energy expenditure (EE) under field conditions. A total of eight Alaskan huskies were fed two experimental diets in a cross-over experiment including two periods of 3 weeks. Effects of diets on EE, apparent total tract digestibility (ATTD) and on plasma hormones, blood lactate and glucose were furthermore investigated. The percentages of metabolisable energy derived from protein (P), fat (F) and carbohydrates (C) were 26:58:16 in the PFC diet and 24:75:1 in the PF diet. Measurements of EE were performed in the post-absorptive state during rest. Blood samples were collected during rest and exercise and ATTD was determined after days with rest and with exercise. EE was higher (P < 0·01) in period 2 than in period 1 (68 v. 48 kJ/kg body weight(0·75) per h). The ATTD of organic matter, crude protein and crude fat was higher (P < 0·01) in the PF diet compared with the PFC diet, and lower (P < 0·01) for total carbohydrates. Exercise did not affect ATTD. Higher (P < 0·01) insulin-like growth factor 1 and leptin concentrations were measured when fed the PF diet compared with the PFC diet. Concentrations of insulin decreased (P < 0·01), whereas cortisol and ghrelin increased (P < 0·05), after exercise. There was no effect of diet on blood lactate and glucose, but higher (P < 0·001) lactate concentrations were measured in period 1 than in period 2. The results suggest that the o(13)CBT can be used in the field to estimate short-term EE in dogs during resting conditions. Higher ATTD and energy density of the PF diet may be beneficial when energy requirements are high.

Effect of Feeding Programs on Broilers Cobb and Arbor Acres plus Performance

The main objective of this study was to determine the effects of various feeding programs (with different energy protein levels) and strain on broiler performance. Three hundred ninety six day old chicks were used in this study. The treatments groups were designed in a 2 x 3 factorial with two commercial strains (Cobb and Arbor Acres Plus) and three dietary programs 1) NRC regimen 2) Single diet (S) and 3) Phase Feeding Regimen (PF). Traits such as fed intake, feed conversion ratio, body weight, production index, mortality and growth rate were recorded for strains and feeding programs. At the end of period there were no significant effects between strains in mentioned traits. But for NRC and PF feed intake was significantly lower than S diet (p 0.05). S diet caused to decrees performance and economical efficiency. Decreasing diet cost and increasing economical efficiency were obtained by PF diet without any response in performance. It was concluded that better performance appeared by Arbor Acres Plus strain in regarding of NRC diet.

Macronutrient self-selection in Solea senegalensis fed macronutrient diets and challenged with dietary protein dilutions

Macronutrient self-selection and responses to dietary protein dilution were investigated in Senegalese sole, a flatfish species of interest for Mediterranean aquaculture. Eight groups of six sole were distributed among 75-l tanks and allowed to feed on three experimental diets composed of pure macronutrients: PC (75% crude protein and 25% carbohydrate), PF (75% crude protein and 25% crude fat) and PFC (10% crude protein, 45% crude fat and 45% carbohydrate). Choosing from the above diets, the sole selected a diet containing 68.0% crude protein, 15.7% crude fat and 16.3% carbohydrate. When the PF diet was diluted 50% with cellulose, the fish increased their feed intake to sustain the energy intake (5.0 kJ/kg BW/day). Their selection of fat remained unchanged, while carbohydrate selection significantly increased by 36% and protein selection slightly decreased by 11%. When both PC and PF were diluted 50% with cellulose, the sole increased their feed intake again to sustain their energy intake (5.2 kJ/kg BW/day). The sole sustained their fat intake, significantly increased their carbohydrate selection by 33%, and significantly decreased their protein selection by 18% compared with the initial situation. These results indicated that Senegalese sole can select from unevenly balanced diets to compose a protein-rich balanced (target) diet, reflecting their carnivorous feeding behaviour. In addition, sole tried to compensate dietary dilutions in order to regulate energy intake by altering their feed intake level and the relative proportions of macronutrients selected.

Effects of six alternative lipid sources on growth and tissue fatty acid composition in Japanese sea bass ( Lateolabrax japonicus)

Ten-week experiment was carried out on Japanese sea bass (5.87 ± 0.02 g) to study the effects of replacement of fish oil with six alternative lipid sources: pork lard, PL; beef tallow, BT; poultry fat, PF; soybean oil, SO; corn oil, CO; and a mixed-fat (MF: tallow, 60%; soy oil, 20%; fish oil, 20%) on growth performance and fatty acid (FA) composition in fillet and liver. Seven isoenergetic and isonitrogenous experimental diets were formulated, containing 10% of added lipid. Fish oil was used in control diet, which was substituted by 50% with the alternative lipid sources in the other six diets. Weight gain (WG), specific growth rate (SGR), Feed conversion ratio (FCR) feed intake and hepatosomatic index (HSI) of fish fed the experimental diets were not significantly different ( P > 0.05). Protein efficiency ratio (PER) in fish fed the PF diet were significantly lower than those of fish fed SO and CO diets. Significant differences in carcass moisture and lipid contents of carcass and liver were observed among fish fed the dietary treatments. Generally, the fatty acid composition of fish fillets and livers reflected the dietary FA composition.

Effect of type of diet (casein-based or protein-free) and caecotrophy on ileal endogenous nitrogen and amino acid flow in rabbits

AbstractTwenty-eight New Zealand White X Californian doe rabbits weighing 3791±141 g were surgically fitted with a glass T-cannula at ileum level. Animals were given ad libitum access to either a casein-based diet (C) or a protein-free diet (PF). The only difference in the ingredient composition of the diets was the substitution of 160g/kg of maize starch by casein in the C diet. Animals were randomly allotted to each experimental diet. Seven rabbits per diet were not allowed to practice caecotrophy. The C diet resulted in higher food dry matter (DM) intake (DMI) (111-5 v. 51-5 g/day), food nitrogen intake (3-12 v. 0-20 g/day), ileal flow of DM (56-0 v. 23-8 g/day) and ileal flow of nitrogen (0-72 v. 0-24 g/day) but lower soft faeces DMI (21-7 v. 41-4 g/day) than the PF diet. A linear relationship between ileal endogenous nitrogen flow and total DMI was found for animals given the C but not for the PF diet. The ingestion ofC diet led to a higher (proportionately 0-41, on average), endogenous ileal amino acid flow than PF diet for all amino acids except for glycine. The ileal flow of glycine was proportionately 0-25 higher in animals given the PF diet than in animals given the C diet. The C diet resulted in higher content of nitrogen, threonine and proline in soft faeces than the PF diet. In contrast, the ingestion of the PF diet led to a higher content of lysine and methionine in soft faeces than the C diet. Within the C diet, animals practising caecotrophy showed higher ileal flow of DM (73-4 v. 56-0 g/day) and phenylalanine (0-834 v. 0-677 g/kg DMI) than animals not practising it. Caecotrophy led to a higher endogenous proportion of some of the most important limiting essential amino acids in rabbits, such as arginine, lysine, phenylalanine and threonine. In rabbits, the use of PF diets has limited practical application in the estimation of nitrogen endogenous losses as the low food DMI and the high soft faecesDMI leads to abnormal food: soft faeces intake ratio. Moreover, due to the important effect of caecotrophy on the amino acid composition of endogenous losses, it is important to correct the total amino acid content of the ileal chyme by the undigested amino acid residue coming from the soft faeces intake. This correction could be made, without the methodological complexity implied, by fitting animals with a wooden collar and thereby avoiding caecotrophy as in the present trial.

Decreased peritoneal macrophage NF-κB translocation to the nucleus in protein energy malnutrition—a role for the glucocorticoid response?

Background & aims: Protein energy malnutrition (PEM) induces immune suppression leading to increased morbidity and mortality. The mechanism(s) underlying PEM-mediated immune suppression remain unclear. Plasma glucocorticoid levels are elevated in PEM and it has been postulated that these increased levels may mediate macrophage (MØ) dysfunction in PEM. We have previously shown that nuclear factor kappa B (NF-κB) activation in response to LPS stimulation is diminished in peritoneal macrophages (PMØs) from PEM mice. We hypothesized that decreased NF-κB activation in lipopolysaccharide (LPS)-stimulated PMØs in PEM is mediated through increased circulating glucocorticoid levels. Methods: Mice were randomized to six groups of n=15 each as follows: (1) control diet (24% casein) (C); (2) protein-free diet (PF); (3) mice with subcutaneously implanted corticosterone pellet on the control diet; (4) mice with subcutaneously implanted placebo pellet on the control diet; (5) adrenalectomized mice on the control diet; (6) adrenalectomized mice on the PF diet. Within each group, the mice were pair-fed for 7 days. At the end of the experimental time period, PMØs were harvested and NF-κB activation determined by electrophoretic mobility shift assay (EMSA). Results: Elevated circulating glucocorticoids diminished NF-κB activation but adrenalectomy failed to restore this diminution in a murine model of PEM. Conclusion: NF-κB translocation to the nucleus in PEM is independent of elevated circulating glucocorticoid levels.

Balancing protein ingredients in carp feeds to limit dischargeof phosphorus and nitrogen into water bodies

ABSTRACT: Through a series of experiments, it has been demonstrated successfullythat an appropriate choice of ingredients is primary for achievinga reduction in phosphorus (P) and nitrogen (N) loading from carpculture. In this final study, four multi-ingredient diets were examined.In addition to the basal ingredients (fish meal 15%, corngluten meal 8%, defatted soybean meal 10%, blood meal3–5%), three of the test diets (PF, MM, and SP)contained 6% each of either poultry feather meal, meatmeal or soy protein concentrate, respectively, and the fourth diet(PMS) had each of the three aforementioned ingredients includedat 3%. These diets had crude protein 3.5 kcal/g,available P between 0.65 and 0.66% and total P rangingfrom 1.26 to 1.36%. The diets were fed to juvenile carpduring a 12-week feeding trial. The highest growth was obtained forfish fed the MM diet. The absorption and retention rates of P werehigher for the PF diet, whereas these values for N did not showtreatment-related differences. The total discharges per ton fish productionwere estimated to range between 7.8 and 9.2 kg for P andbetween 39.1 and 40.7 kg for N. These were lower than thefigures for Lake Kasumigaura, a main carp culture site, indicatingthat proper balancing of protein ingredients aids in efficientlylowering emissions from aquaculture.

Self-selection of diets with different amino acid profiles by rainbow trout ( Oncorhynchusmykiss)

The ability of rainbow trout to self-select a suitable feed among semi-purified diets with (1) a high protein (crude protein; CP=40%) and a balanced amino acid profile (casein:gelatin=6:1, BAL), (2) a high protein and an imbalanced amino acid profile (1:6, IMB), (3) a low protein (CP=15%) and a balanced amino acid profile (LP), and (4) a protein-free diet (PF), were examined using self-feeders. In experiment 1, combinations of two diets (BAL and IMB; BAL and PF; IMB and PF) were used. For each combination, four individually housed trout were provided with the diets. After an initial 2-week period, the positions of the two feed containers were exchanged and feeding continued for 3 more weeks. In the first 2 weeks, trout predominantly selected the BAL diet to the IMB or PF diet, although some fish failed to switch when the feeders were exchanged to obtain the BAL diet during the latter 3 weeks. In experiment 2, two combinations of four diets, BAL, two IMB and PF, or LP, IMB and two PF, were each offered to five individual trout for 3 weeks. Trout then showed preference for the BAL diet to the IMB and PF diets, and the LP diet to the IMB and PF diets. The preference for the BAL or LP diet gradually increased as the feeding trial progressed. These results suggest that trout preferred a casein-rich balanced amino acid diet regardless of its dietary protein level to a gelatin-rich imbalanced diet or a protein-free diet.

Inanition may Reduce Alkaline Phosphatase Activity in Liver and Intestine of Zinc-Deficient Mice

Zinc-deficiency was induced in mice by feeding a Zn-deficient basal diet (ZD dietary group) containing 9% lipid (6% corn oil, 3% cod liver oil) for 8 wk. Thereafter, the corn oil was withdrawn from the basal diet and a subset of Zn-deficient animals (ZDLR group) was fed this modified low fat diet for another 8 wk. Alkaline phosphatase activity in intestine and liver was compared in these mice and in those allowed ad libitum access to the lipid-adequate Zn-supplemented diet (ZS group), in those pair-fed the Zn-supplemented diet (PF group) and in those fed the lipid-adequate, Zn-deficient diet ad libitum (ZD group). The enzyme activity in both intestine and liver of the ZDLR group was greater than in those of the ZD group and greater than or equal to those of the ZS and PF diet groups. The results of this study suggest that the reduction in alkaline phosphatase in Zn-deficient animals is a response secondary to associated inanition.

Regulation of Rat Hypothalamic PreproGrowth Hormone-Releasing Factor Messenger Ribonucleic Acid by Dietary Protein

To further evaluate nutrient regulation of GRF synthesis, we measured hypothalamic preproGRF messenger (m) RNA in food-deprived rats refed diets varying in nutrient composition by nuclease protection analysis. Adult male Sprague-Dawley rats were allowed free access to food (Fed), food deprived for 72 h (72-h FD), or 72 h FD then refed for 72 h with either a normal (NF) diet or isocaloric diets containing no protein (PF), carbohydrate (CF), or fat (FF). Seventy-two-hour FD rats displayed the expected 80% reduction in hypothalamic preproGRF mRNA. Upon refeeding, levels were normalized in rats refed NF, CF, or FF diets. In contrast, preproGRF mRNA in rats refed a PF diet was similar to that in 72-h FD rats. Rats refed a PF diet failed to gain weight and consumed less food than animals refed NF, CF, or FF diets. However, the lack of the GRF response to the PF diet was due to protein deprivation rather than caloric restriction, since hypothalamic preproGRF mRNA returned to 66% of Fed values in rats refed an equivalent amount (grams per day) of a NF diet. In 72-h FD rats refed isocaloric diets containing 4%, 8%, or 12% protein, preproGRF mRNA was restored to Fed values in a protein concentration-dependent manner being completely restored by the 12% diet. A lack of dietary protein was sufficient to regulate hypothalamic preproGRF mRNA since feeding rats a PF diet without prior food deprivation resulted in 70% reduction in preproGRF mRNA, whereas CF and FF diets were without effect. These data indicate that decreased hypothalamic preproGRF mRNA expression in 72-h FD rats occurs as a result of dietary protein deprivation.

Effects of protein-free diet in amino acid homeostatis of rat blood plasma and gut contents

Amino acids in rat systemic and portal vein plasma and jejunal and ileal gut contents after 7 days of feeding normoprotein (NP) and protein-free diet (PF) are investigated. Amino acid analyses revealed that ingestion of PF diet resulted in unusual amino acid patterns in both plasmas. Thus, while the levels and/or molar ratios of all indispensable amino acids were significantly decreased, those of several gluconeogenetic amino acids, especially of glycine and alanine, were increased in both plasmas, but particularly in portal. By contrast, the molar ratios of the majority of amino acids in jejunal and ileal contents were not changed by PF diet.

Changes in Body Weight and Composition of Adult Nongravid Female Rats Deprived of Dietary Protein

Seventy-six young adult nongravid female rats of the Carworth strain were used in two experiments to study the effect of dietary protein deprivation on body weight, feed consumption, body composition and serum protein concentration. Semipurified diets containing glucose, corn oil, vitamins and minerals with or without casein (protein-free = PF, 14% casein = C) were fed ad libitum in both experiments to rats caged in individual wire-bottom cages. Feeding the PF diet for up to 26 days resulted in a continuous weight loss over the entire period. The average loss in body weight as a percentage of initial weight of PF rats in experiments 1 and 2 was 32.9 and 25.7, respectively. Weight loss during 9 days in rats fed the PF diet was restored within 8 days following transfer to the C diet. Feed consumption was reduced only moderately by the PF diet, suggesting a large loss of ingested calories by excretion or metabolism to carbon dioxide and water. Body composition data supported this and indicated a greater relative loss of body energy than of body protein in PF rats. Blood serum protein concentration was reduced moderately (P < 0.05) in rats fed the PF diet. The absolute loss of serum protein may have been greater than suggested by the concentration if it is assumed that there was a reduction in blood volume associated with the observed weight loss. Blood serum protein concentration therefore does not appear to be as sensitive an index of protein nutrition in the adult as in the young animal. Final body energy, protein and water content were less in PF rats than in C rats in experiment 2 by an average of 176.5 kcal (36%), 10.9 g (23%) and 41.7 g (28%), respectively. Energy concentration (kilocalories per gram dry weight) was 11% greater in C than in PF rats (5.8 versus 5.2 kcal/g). These data indicate that the adult female nongravid rat can survive a loss of at least one-third of body energy and one-fourth of body protein induced by protein deprivation without developing severe hypoproteinemia, emaciation and edema.