Low Levels Of Supplementation Research Articles

T3 supplementation affects ventilatory timing & glucose levels in type 2 diabetes mellitus model

Type II diabetes mellitus (T2DM) can affect ventilation, metabolism, and fasting blood glucose levels. Hypothyroidism may be a comorbidity of T2DM. In this study T2DM was induced in 20 female Sprague Dawley rats using Streptozotocin (STZ) and Nicotinamide (N). One of experimental STZ/N groups (N=10 per group) was treated with a low dose of triiodothyronine (T3). Blood glucose levels, metabolism and ventilation (in air and in response to hypoxia) were measured in the 3 groups. STZ/N-treated rats increased fasting blood glucose compared to control rats eight days and 2 months post-STZ/N injections indicating stable induction of T2DM state. Treatments had no effects on ventilation, metabolism or body weight. After one month of T3 supplementation, there were no physiological indications of hyperthyroidism, but T3 supplementation altered ventilatory timing and decreased blood glucose levels compared to STZ/N rats. These results suggest that low levels of T3 supplementation could offer modest effects on blood glucose and ventilatory timing in this T2M model.

Effect of guava leaves on growth and the non-specific immune response of Penaeus monodon

Guava (Psidium guajava L.) leaf extracts have antiviral and antibacterial activity against shrimp pathogens such as yellow-head virus (YHV), white spot syndrome virus (WSSV), and Vibrio harveyi, which make it a potential water disinfectant for use in shrimp culture. In this study, the safety of guava leaf supplementation in shrimp was evaluated by studying its influence on growth and the non-specific immune response of Penaeus monodon. Six diets containing different levels of guava leaves (0% [basal diet], 0.025% [G1], 0.05% [G2], 0.1% [G3], 0.2% [G4], and 0.4% [G5]) were fed to groups of shrimp (1.576 ± 0.011 g body weight) in triplicate for 56 days. Growth performance (final body weight, WG, PWG, SGR) of shrimp fed guava leaf diets was significantly higher (P < 0.05) than that of shrimp fed on the basal diet. The G1 diet resulted in the highest body weight gain (308.44%), followed by the G2 (295.45%), G3 (283.05%), G5 (281.29%), G4 (276.11%), and finally the basal diet (214.58%). Survival of shrimp in the G1 diet group was higher than that of shrimp in the control and the other experimental groups; however, no statistical differences (P > 0.05) were found. Dietary supplementation with guava leaf improved the activities of prophenoloxidase (PO) and nitric oxide synthase (NOS) in serum, and of superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LSZ) both in serum and hepatopancreas of shrimp. In the experimental groups, the activities of these enzymes followed a similar pattern of change; they increased initially at low levels of dietary supplementation and then decreased with increasing concentrations of dietary guava leaf. Serum PO and SOD activities in shrimp fed the G1 diet reached 7.50 U ml−1 and 178.33 U ml−1, respectively, with PO activity being significantly higher than in controls. In shrimp fed the G1 diet, SOD, ACP, and AKP activities in hepatopancreas were significantly higher than in the controls, reaching 57.32 U g−1, 23.28 U g−1, and 19.35 U g−1 protein, respectively. The highest activities of serum ACP, AKP, LSZ, and of hepatopancreas LSZ, were observed in the G3 diet group. Total nitric oxide synthase (TNOS) activity was highest (64.80 U ml−1) in the G4 diet group, which was significantly higher than that observed in the control group. These results suggest that dietary guava leaf supplementation could enhance the growth performance and non-specific immune response of P. monodon. Therefore, guava leaf is considered safe for use as a water disinfectant in shrimp culture.

Zinc oxide at low supplementation level improves productive performance and health status of piglets

Use of ZnO at high doses (3000 ppm) for diarrhea prophylaxis in piglets is widely extended in postweaning Spanish diets, in compliance with the national veterinary regulation. However, European feed legislation limits total dietary Zn to a maximum of 150 mg/kg of complete feed. The objective of this study was to compare a new potentiated form of ZnO, HiZox (Animine), at nutritional level (150 ppm) with pharmacological dosage (3000 ppm) of regular ZnO in starter diets on the productive performance and health status of piglets in a medium-low health status farm. A total of 144 pigs at weaning (28 d of age) were distributed in 6 piglets/pen and 12 pens/treatment. In the prestarter phase (28 to 42 d of age), all pigs received the same commercial feed, including 3000 ppm ZnO. In the starter phase (42 to 63 d of age) (T1) included 3000 ppm of regular ZnO (2500 ppm Zn), and (T2) was supplemented with 110 ppm Zn from potentiated ZnO (HiZox). Average daily feed intake, ADG, G:F, and pig-MAP serum concentration, an acute phase protein commonly used as unspecific biomarker of disease or other acute phase reactions, were measured at 42 and 63 d of life. Pen of 6 piglets was the experimental unit and data were analyzed using the GLM procedure of SAS version 9.0. Piglets fed with T2-HiZox had improved ADG and G:F (P < 0.001) compared to piglets fed with T1-ZnO. In addition, at 63 d of age, the T2 group had a lower pig-MAP serum concentration than T1 group (1.71 vs. 0.95 μg/mL; P < 0.05) indicating higher health status in the T2 group. In conclusion, in low-medium sanitary conditions and in compliance with European regulation, HiZox significantly increased piglet growth compared to pharmacological dosage of regular ZnO in the starter phase. This can be explained by a better health of pigs expressed by a lower level of inflammatory protein pig-MAP.

Feeding Blueberry Diets Dose‐Dependently Inhibits Bone Resorption in Young Rats

Nutritional status is a critical factor that influences bone development. We previously reported that weanling rats fed AIN‐93G semi‐purified diets supplemented with 10% whole blueberry (BB) powder for only two weeks beginning on postnatal day 21 (PND21) significantly promoted bone formation. However, whether there is an effect of BB diet on bone at lower levels of supplementation or if there are additional effects on bone resorption is unknown. The current study examined the effects of three levels of BB diet supplementation (1, 3, and 5%) for 14 days beginning on PND21on osteoclastic bone resorption. Using peripheral quantitative CT scan of tibia, we demonstrated that bone mineral density and content were dose‐dependently increased in BB rats compared to control AIN‐93G fed animals (p &lt; 0.05). Proteins were isolated from long bone of femurs, and Western blot revealed that RANKL (the cytokine receptor activator of nuclear factor‐κB ligand essential for osteoclast formation) protein expression was dose‐dependently decreased (p&lt;0.05). This was accompanied by decreased expression of PPARγ, RANKL and TRAP (Tartrate‐resistant acid phosphatase) mRNA expression (p&lt;0.05). These results indicate significant stimulation of bone growth by dose‐dependent inhibition of bone resorption after BB consumption during early development. Supported in part by ARS CRIS #6251‐51000‐005‐03S.Grant Funding Source: USDA / ARS CRIS

Effects of thyroid hormone supplementation on ventilation and metabolism in a rat model of Type 2 Diabetes

Thyroid hormone supplementation can have beneficial effects in type 2 diabetes (T2D). In this study T2D was induced in thirty young female rats by an intraperitoneal (ip) injection of nicotinamide (200 mg/kg) followed 15 minutes later by an ip injection of streptozotocin (65 mg/kg, STZ/N). Control rats (CR, n=10) received vehicle injections. After 2 months, subgroups of STZ/N rats received either 4 (STZ/N4) or 8ug/kg/day (STZ/N8) of triiodothyronine (T3) in drinking water for one month. Subsequent metabolic and ventilatory studies (during exposure to air or hypoxia, 10% O2 in N2) indicated little effects in the STZ/N group compared to CR. In contrast, STZ/N8 group was clearly hyperthyroid with lower body weights, elevated body temperatures, metabolic rates, and ventilation during exposure to air and hypoxia. Except for changes in inspiratory (increased) and expiratory (decreased) times during air exposure, the ventilation and metabolism of the STZ/N4 group was similar to the CR and STZ/N groups. Importantly, the lower, but not higher dose of T3 attenuated the hyperglycemia observed in both the STZ/N and STZ/N8 groups. Thus, low levels of T3 supplementation may have beneficial effects in T2D, but have subtle effects of ventilatory timing parameters during air exposure. Funded by R01 7R01HL093160‐03 (from NHLBI) and a Clinical Scientist Training Award from the American Diabetes Association (ADA 7‐10‐CST‐01).

Selectively Hydrogenated Soybean Oil Exerts Strong Anti‐Prostate Cancer Activities

Prostate cancer is the second leading cause of male deaths due to cancer in the United States. Hydrogenated vegetable oils have been suspected of inducing adverse health effects, including atherosclerosis and cancer. Here we report that a selectively hydrogenated soybean oil (SHSO) containing a high quantity of conjugated linoleic acids showed remarkably strong anticarcinogenic activity against prostate cancer in the rat model (Copenhagen rats with MAT-LyLu syngeneic rat prostate cancer cells) study in vivo and human prostate carcinoma cell lines studies in vitro, as compared with native soybean oil. A 5% dietary supplementation with SHSO inhibited the growth of prostate cancer by 80% in vivo. The TUNEL method and immunohistochemical staining assays of bax, bcl-2, and survivin clearly showed that SHSO induced prostate cancer cell apoptosis in the tested rats. DNA fragmentation analysis in vitro further confirmed the apoptotic activity of SHSO on the MAT-LyLu prostate cancer cells. The SHSO also showed strong cytotoxicity on human prostate cancer cells (DU145 and PC3). This represents the first report demonstrating the significant anticancer activities of hydrogenated vegetable oils at low levels of dietary supplementation.

Effect of Source and Level of Maternal Vitamin D on Carryover to Newly Hatched Chicks

A study was conducted to evaluate the carryover effect of maternal vitamin D level and source on performance and bone development of the progeny. Breeder hens were fed a vitamin D deficient diet for two months to deplete stores. After this period, experimental diets in a factorial arrangement were fed to the hens with five levels of cholecalciferol (0, 300, 600, 1200 and 2400 IU/kg) and two levels of 25OHD3 (HyD) (0 and 68 µg/kg) for a total of 10 treatments. At the end of two months on the experimental diets two sets of eggs were hatched. The progeny obtained were placed in battery brooders to 21 days by maternal diet and received a common diet. The first hatch received a diet with no vitamin D supplement whereas the second hatch received a diet with the same nutrient composition but containing 5500 IU/kg of cholecalciferol. The first set of birds responded to the maternal diet supplementation of vitamin D mostly during the first week post hatch with no clear pattern in later stages. The progeny receiving 5500 IU/kg of vitamin D in the diet responded to the maternal vitamin D supplementatio n even at 21 days and in a clearer trend. Feed conversion and body weight improved as the cholecalciferol level increased and with the inclusion of HyD in the maternal diet. The response when HyD was added was more noticeable at low levels of cholecalciferol supplementation with no difference at higher levels in the hen's diet. Bone development of the progeny was improved with the addition of HyD in the maternal diet; this response was not influenced by increasing levels of cholecalciferol in the breeder diet. This study confirms the importance of the maternal vitamin D carryover for an adequate development of the progeny. Certainly, the vitamin D carryover effect did not overcome the effect of supplementing vitamin D directly in the progeny's diet but it was capable of improving the performance of the progeny even three weeks post-hatch when a high level of cholecalciferol (5500 IU/kg) was present in th e diet of the progeny. A carryover effect of HyD when added to the maternal diet was observed in this study, thus the feasibility of using the metabolite to supply vitamin D to the developing embryo was confirmed.

Suplementação de vacas holandesas em estádio avançado de lactação

O objetivo deste trabalho foi avaliar o efeito de duas dietas: baixo e alto nível de suplementação, fornecidas a vacas em estádio avançado de lactação sobre os aspectos produtivos, as características físico-químicas do leite e o perfil bioquímico sanguíneo. Foram utilizadas 12 vacas da raça Holandês, com média de 514kg de peso corporal, escore de condição corporal 3,5, produção de leite de 13 litros vaca-1 dia-1, com média de 349 dias de lactação. Os tratamentos foram: baixo e alto nível de suplementação para vacas mantidas em campo natural. Foram avaliados o peso vivo, o escore de condição corporal, a produção leiteira individual, as características físico-químicas e a contagem de células somáticas do leite (CCS), além do perfil bioquímico do sangue. As vacas, mesmo em estádio lactacional avançado, responderam ao aumento do aporte nutricional, com incrementos de ganho de peso, ganho de condição corporal e de produção de leite e produção leiteira corrigida para gordura, além de maiores teores de gordura e de sólidos totais. As demais características do leite e do sangue não foram alteradas. O aumento do aporte nutricional de vacas lactantes com estádio de lactação avançado pode ser uma opção viável para alcançar maior nível de produção leiteira e melhores condições físicas das vacas em sistemas de produção baseadas na utilização de pastagem, sem afetar adversamente a concentração dos componentes lácteos.

Effect of supplementation of Simada sheep with graded levels of concentrate meal on feed intake, digestibility and body-weight parameters

The experiment consisting of 7 days of digestibility and 90 days of feeding trial was conducted at Wogda (Ethiopia) to determine the effect of supplementation of graded levels of concentrate mix (CM) on feed intake, digestibility, and body weight (BW) change in hay-based feeding of Simada sheep. Twenty-yearling Simada sheep with a mean initial BW of 17.9 +/- 0.81 kg (mean +/- SD) were used in randomized complete block design arranged into five blocks of four animals. The four dietary treatments that consisted of hay alone (T1), hay +150 g dry matter (DM; T2, low), hay +250 g DM (T3, medium), and hay +350 g DM (T4, high) CM were randomly assigned to each sheep within a block. The CM consisted of wheat bran (WB), noug seed (Guizotia abyssinica) meal and safflower (Carthamus tinctorius) seed meal at the ratio of (2:1:1), respectively. Supplementation with T2 and T3 increased (P < 0.001) total DM and organic matter intake than the control treatment. Overall, supplementation improved (P < 0.001) crude protein intake, digestibility, feed conversion efficiency, BW gain, and profitability compared to the control, whereas sheep on the high than the low and medium level of supplementation performed better in these parameters among the supplemented treatments. From the results of this study, T4 is recommended as the best level of supplementation since it resulted in better nutrient utilization, animal performance, and profitability.

Effects of source and level of fish oil supplementation in late pregnancy on feed intake, colostrum production and lamb output of ewes

Supplementing pregnant ewes with fish oil to enhance the dietary supply of 20:4 n-6 and 22:6 n-3 has the potential to improve neonatal vigour and increase lamb survival rates. However, dietary fish oil has been shown to reduce colostrum production of ewes which can adversely affect lamb survival. To investigate the effects of source and level of fish oil in this response, 55 twin-bearing ewes were offered grass silage (0.5 kg dry matter per day) plus concentrates (0.5 kg/d) and supplemented with 0, 20 or 40 g/d herring (H) or salmon oil (S) during the final 6 weeks of pregnancy, giving a total of 5 treatments being control, H20, H40, S20 and S40. Salmon oil increased the supply of 18:2 n-6 (2.37) and 22:4 n-6 (1.98) but reduced the supply of 22:6 n-3 (0.84) relative to herring oil. Silage DM intake was marginally lower for S40 ewes ( P<0.05) but there were no dietary effects on ewe live weight or body condition score. Plasma non-esterified fatty acids (NEFA) ( P<0.05) and urea ( P<0.001) concentrations were elevated in ewes fed fish oil. Lambs born to control ewes had higher serum IgG concentrations than those fed herring oil ( P<0.01). Colostrum output at 10 h ( P<0.01) and total yield of colostrum ( P<0.05) were lower for fish oil-supplemented ewes. Concentrations of 10 h IgG ( P<0.05), 18 h fat ( P<0.001), 18 h total solids ( P<0.05) as well as outputs of fat ( P<0.05), protein ( P<0.01), casein ( P<0.05), IgG ( P<0.001) and total solids ( P<0.05) were reduced by feeding fish oil. Compared with controls, ewes fed herring oil had a higher 10 h lactose concentration ( P<0.05) while those fed salmon oil had lower outputs of 18 h protein ( P<0.05) and 18 h casein ( P<0.05). Offering 20 g/d, but not 40 g/d, fish oil increased the number of lambs weaned (+0.55 lambs/ewe; P=0.06) and the total output of weaned lamb (19.4 kg; P<0.05), but otherwise there were no effects of fish oil level and source on ewe or lamb performance. Results indicate that low levels of crude fish oil supplementation (up to 20 g/d) during late pregnancy improved lamb survival and output at weaning, but these benefits disappeared at higher inclusion rates.

The Effects of Lower Supplementation Levels of Organically Complexed Minerals (Zinc, Copper and Manganese) Versus Inorganic Forms on Hematological and Biochemical Parameters in Broilers

Summary The present study was carried out to investigate the effects of replacing inorganic with at lower level of organically complexed minerals (Zn, Cu and Mn) on hematological and biochemical parameters in broilers. A total of two hundred Ross-308 one-day-old broiler chickens were used. Chicks were randomized into 1 control and 3 treated groups each containing 50 chicks and each experimental group comprised 5 of subgroups including 10 chicks. Mineral content of the control diet was prepared according to National Research Council (NRC) as inorganic salts. In treated groups, organically complexed Zn, Cu and Mn were separately added into the basal diet at 1/3 (group 1), 2/3 (group 2) and 3/3 (group 3) proportions as Bioplex TM , instead of inorganic levels of those minerals recommended by NRC, respectively. The plasma Zn level significantly increased as the serum Cu level significantly decreased (P<0.05) in chickens fed at 2/3 and 3/3 levels of organic minerals. The hemoglobin concentration and packed cell volume were significantly higher in group L1. Total leukocyte count and peripheral blood leukocyte type were in the normal range reported in both the control and organic mineral supplemented groups. As the high density lipoprotein (HDL)-cholesterol level increased, low density lipoprotein (LDL)-cholesterol and total cholesterol levels decreased in chickens fed organically complexed minerals. Results showed that using at much lower level organically complexed minerals (Cu, Zn and Mn) in broiler diets instead of inorganic forms of those minerals

Effect of finishing diet on consumer acceptability of Uruguayan beef in the European market

Eighty Hereford steers were used to evaluate the effect of finishing diet [A: pasture, B: pasture plus concentrate (0.6% live weight), C: pasture plus concentrate (1.2% live weight), D: concentrate] on consumer acceptability of Uruguayan beef in France (FR), United Kingdom (UK), Spain (ES) and Germany (DE). Consumers (200 per country) evaluated overall, tenderness and flavour acceptability of beef (8 point scale: 1 ‘dislike extremely’, 8 ‘like extremely’). FR and UK rated lower acceptability scores for beef from D compared with A, B, and C. ES showed similar results for tenderness, but flavour scores did not differ between A and D. German consumers preferred beef from B and C. Overall, low levels of supplementation on pasture produced beef with the highest consumer acceptability followed by beef from pasture-fed animals. Feeding cattle with concentrate only may not be necessary to satisfy the EU market resulting in more profitable production systems for Uruguayan producers.

Influence of Vitamin E Source and Dietary Supplementation Level on Production Performance of Sunshine Bass, Morone chrysops ♀ × Morone saxatilis ♂, Fillet Tocopherol Content, and Immunocompetency during Stress and Bacterial Challenge

Abstract We evaluated the effects of dietary vitamin E concentration and source on production performance and immunocompetency of sunshine bass, Morone chrysops × Morone saxatilis, following stress and disease challenge. Four diets were formulated to contain requisite levels (1×) or five times (5×) the vitamin E requirement of sunshine bass as met by synthetic vitamin E (SYNE) or natural source vitamin E (NSVE). Each diet was fed to juvenile sunshine bass for 8 wk prior to experimental challenges. Replicate tanks within each dietary treatment were challenged with stressor exposure (chasing with dip net), incidental Flavobacterium columnare exposure, or both; control groups were not challenged. Pathogen and/or stressor exposure largely resulted in significant reductions in immunological performance. Although significant independent dietary effects were not observed among immunological parameters, suppression of complement and macrophage respiratory burst activities was numerically lower within the 5× NSVE treatment. Production performance was largely unaffected by dietary vitamin E source or level. Fillet α‐tocopherol concentration was significantly higher among fish fed the 5× diets (40.7/41.6 vs. 12.2/14.5 μg/g dry tissue for 1× diets); however, the dietary concentration required to achieve these levels was lower for NSVE. Although super‐requirement levels of either source of vitamin E were apparently beneficial, NSVE was effective at ∼50% lower supplementation levels.

Effect of frequency and amount of rumen-degradable intake protein supplementation on urea kinetics and microbial use of recycled urea in steers consuming low-quality forage1

We evaluated the effect of frequency and amount of rumen-degradable intake protein (DIP) on urea kinetics in steers consuming prairie hay. Five ruminally and duodenally fistulated steers (366 kg of BW) were used in a 5 x 5 Latin square and provided ad libitum access to low-quality prairie hay (4.7% CP). Casein was provided daily in amounts of 61 and 183 mg of N/kg of BW (61/d and 183/d) and every third day in amounts of 61, 183, and 549 mg of N/kg of BW per supplementation event (61/3d, 183/3d, and 549/3d). Periods were 18-d long with 9 d for adaptation and 9 d for collection. Steers were in metabolism crates for total collection of urine and feces. Jugular infusion of (15)N(15)N-urea followed by determination of urinary enrichment of (15)N(15)N-urea and (14)N(15)N-urea was used to determine urea kinetics. Treatment means were separated to evaluate the effects of increasing DIP supplementation and the effects of frequency at the low (61/d vs. 183/3d) and at the high (183/d vs. 549/3d) amounts of DIP provision. Forage OM and total digestible OM intakes were linearly (P < or = 0.05) increased by increasing DIP provision but were not affected by frequency of supplementation at either the low or high amounts. Production and gut entry of urea linearly (P < or = 0.006) increased with DIP provision and tended to be greater (P < or = 0.07) for 549/3d than 183/d but were not different between 61/d and 183/3d. Microbial N flow to the duodenum was linearly (P < 0.001) increased by increasing DIP provision. Additionally, 183/d resulted in greater (P = 0.05) microbial N flow than 549/3d. Incorporation of recycled urea-N into microbial N linearly (P = 0.04) increased with increasing DIP. Microbial incorporation of recycled urea-N was greater for 549/3d than 183/d, with 42 and 23% of microbial N coming from recycled urea-N, respectively. In contrast, there was no difference due to frequency in the incorporation of recycled urea-N by ruminal microbes at the low level of supplementation (i.e., 61/d vs. 183/3d). This study demonstrates that urea recycling plays a substantial role in the N supply to the rumen and to the animal, particularly in steers supplemented infrequently with high levels of protein.

A Comparison of Three Strains of Holstein-Friesian Grazed on Pasture and Managed Under Different Feed Allowances

This experiment compared Holstein-Friesian (HF) cows of New Zealand (NZ) origin representative of genetics present in the 1970s (NZ70; n=45) and 1990s (NZ90; n=60), and a group of HF cows of North American origin with 1990s genetics (NA90; n=60), which were managed in grazing systems with a range of feeding allowances (4.5 to 7.0 t/cow per yr) over 3 yr. The NZ70 cows had the lowest Breeding Worth genetic index and the lowest breeding values for yields of fat, protein, and milk volume; the NZ90 and NA90 cows were selected to have similar breeding values for milk traits and were representative of cows of high genetic merit in the 1990s. The NZ90 cows had a higher milk protein concentration (3.71%) than either the NA90 (3.43%) or the NZ70 cows (3.41%), and a higher milk fat concentration (4.86%) than the NA90 cows (4.26%) with a level similar to the NZ70 cows (4.65%). The NZ90 cows produced significantly greater yields of fat, protein, and lactose than the NA90 and NZ70 cows. The NZ70 cows had the lowest mean annual body weight (473kg) but the highest body condition score (BCS; 5.06). Days in milk were the same for the 2 NZ strains (286 d in milk), both of which were greater than the NA90 cows (252 d in milk). There was no genotype × environment interaction for combined milk fat and protein yield (milksolids), with NZ90 producing 52 kg/cow more than the NA90 at all feeding levels. The NZ70 strain had the highest seasonal average BCS (5.06), followed by the NZ90 (4.51) and the NA90 (4.13) strains on a 1 to 10 scale. Body condition score increased with higher feeding levels in the 2 NZ strains, but not in the NA strain. The first-parity cows commenced luteal activity 11 d later than older cows (parities 2 and 3), and the NA90 cows commenced luteal activity 4 and 10 d earlier than the NZ70 and NZ90 cows. Earlier estrus activity did not result in a higher in-calf rate. The NZ70 and NZ90 cows had similar in-calf rates (pregnancy diagnosed to 6 wk; 69%), which were higher than those achieved by NA90 cows (54%). Results showed that the NA90 strain used in this experiment was not suitable for traditional NZ grazing systems. Grazing systems need to be modified if the NA90 strain is to be successfully farmed in NZ. The data reported here show that the NA90 cows require large amounts of feed, but this will not prevent them from having a lower BCS than the NZ strains. Combined with poor reproductive performance, this means that NA90 cows are less productive than NZ HF in pasture-based seasonal calving systems with low levels of supplementation.

Diet and genotype effects on the quality index of beef produced in the Argentine Pampeana region

Steers of varying genotypes (Aberdeen Angus, Charolais x AA and Argentine Holstein) in four feeding systems were evaluated. Feeding systems were: S1=a diet based on pastures only; S2=a similar forage base as S1 plus a daily supplementation with cracked corn, at 0.7% of l.w./head/day; S3=a similar forage base as S1 plus a daily supplementation with cracked corn, at 1.0% of l.w./head/day; and S4=a regular feedlot diet. Tenderness and marbling were not affected by the feeding system. Feedlot meat showed an n-6/n-3 ratio significantly higher than meat produced with the diets based on pastures (S1=2.1; S2=3.1; S3=4.5; S4=14.2) (P<0.05), whereas CLA content had an inverse behavior, showing S1 (0.67%) and S2 (0.64%) higher concentrations than S3 (0.55%) and S4 (0.28%) (P<0.05). Diet based on pastures plus a low level of supplementation produced meat with better nutritional characteristics than other productive alternatives, without significant effects of the biotypes.

Stochastic simulation of rumen degradable protein surplus in grazing dairy cows

In grazing systems, the quality of the pasture is an ever-changing scenario: weather, forage variety, level of fertilisation and age of the plant are some of many factors influencing the quality of the cows’ diet. Furthermore, accurate dry matter intake measurements are difficult to obtain under grazing conditions. As a result, the use of mathematical models to describe aspects of pasture digestion has been limited in practice. Stochastic modelling might overcome this limitation. In the current example, a static model of cow digestion (National Research Council (NRC), 2001. Nutrient Requirements of Dairy Cattle. National Academy Press, Washington, DC, USA) was coded into a software package for probabilistic simulation (GoldSim v. 9.2) using stochastic variables for pasture chemical composition and dry matter intake. Partitioning of crude protein (nitrogen) in the rumen of cows was simulated over a period of 7 weeks in early spring to estimate the potential losses of nitrogen due to high ruminal degradability of protein when different levels and types of supplementary feeds were offered. More than 98% of the simulations resulted in estimated excess of rumen degradable protein of up to 561 g N/d. By comparison, the magnitude of deficit was small (up to −42 g N/d) in the simulations with negative values for rumen degradable protein balance. Pasture crude protein concentration was the stochastic variable with the biggest influence on the amount of rumen degradable protein. Higher levels of supplementation (60 g DM supplements per 100 g DMI) resulted in estimated excess rumen degradable protein that was 0.3 of that obtained from simulations with lower levels of supplementation (35 g DM supplements per 100 g DMI). Stochastic simulation may be useful to explore the likelihood of responses to management scenarios designed to increase the efficiency of dietary nitrogen utilisation in pastoral systems characterised by uncertainty and variability.

Inbreeding dynamics in reintroduced, age-structured populations of highly fecund species

Reintroduction programs aim at reinstalling a self-sustained population into the wild via a period of supplementation with captive-bred individuals. This procedure can rapidly generate inbreeding among offspring because of the mating scheme and this inbreeding might be further enhanced by the reintroduction scenario. First, we used simulations to assess the consequences of breeding designs on mean inbreeding index F among offspring when the genetic diversity of breeders, the number and sex ratios of breeders, and the proportion of successful crosses vary. A high number of breeders, a balanced sex ratio, a high proportion of effective crosses and a genetically diverse source population generally contribute to lower F values. However, moderately high (≥20) numbers of breeders combined with all but the most biased sex ratios produced mean F values near minimal values. The variability in F was negligible in all parameter combinations except for a very small number of breeders (5) and very biased sex ratios (≤ 1M : 19F). We also simulated the long-term inbreeding dynamics in the introduced population under various demographic scenarios. Our main finding was that the annual number of introduced offspring is a decisive factor in establishing long-term F values in the supplemented population. Low supplementation levels (102) quickly generated an almost completely inbred population whereas high levels (≥104) produced stable F values close to that of the introduced offspring. Simulations were run based on the life history and specific demographics of the bloater (Coregonus hoyi), whose reintroduction in Lake Ontario is being considered.

Effects of stocking rate and corn gluten feed supplementation on performance of young beef cows grazing winter-stockpiled tall fescue-red clover pasture1

A winter grazing experiment was conducted to evaluate the effects of stocking rate and corn gluten feed supplementation on forage mass and composition and the BW and BCS of bred 2-yr-old cows grazing stockpiled forage during winter. Two 12.2-ha blocks containing Fawn, endophyte-free, tall fescue and red clover were each divided into 4 pastures of 2.53 or 3.54 ha. Hay was harvested from the pastures in June and August of 2003 and 2004, and N was applied at 50.5 kg/ha at the initiation of stockpiling in August. On October 22, 2003, and October 20, 2004, twenty-four 30-mo-old Angus-Simmental and Angus cows were allotted by BW and BCS to strip-graze for 147 d at 0.84 or 1.19 cow/ha. Eight similar cows were allotted to 2 dry lots and fed tall fescue-red clover hay ad libitum. Corn gluten feed was fed to cows in 2 pastures to maintain a mean BCS of 5 (9-point scale) at each stocking rate and in the dry lots (high supplementation level) or when weather prevented grazing (low supplementation level) in the remaining 2 pastures at each stocking rate. Mean concentrations of CP in yr 1 and 2 and IVDMD in yr 2 were greater (P < 0.10) in hay than stockpiled forage over the winter. At the end of grazing, cows fed hay in dry lots had greater (P < 0.05) BCS in yr 1 and greater (P < 0.10) BW in yr 2 than grazing cows. Grazing cows in the high supplementation treatment had greater (P < 0.10) BW than cows grazing at the low supplementation level in yr 1. Cows in the dry lots were fed 2,565 and 2,158 kg of hay DM/cow. Amounts of corn gluten feed supplemented to cows in yr 1 and 2 were 46 and 60 kg/ cow and did not differ (P = 0.33, yr 1; P = 0.50, yr 2) between cows fed hay or grazing stockpiled forage in either year. Estimated production costs were greater for cows in the dry lots because of hay feeding.

Milk Yield and Composition of Grazing White Fulani Cows Fed Poultry Waste-Cassava Peel Based Diets

The influence of supplementation of poultry waste-cassava peel based diets on milk yield and composition of White Fulani (Bunaji) cows were evaluated in this study. Four cows in 2nd parity and midlactation stage were fed 4 concentrate diets (A, B, C, D) consecutively in a 4x4 latin square arrangement. The diets were formulated from poultry waste, cassava peel, palm kernel cake, molasses, bone meal and common salt. The percent compositions of dried poultry waste (DPW) and cassava peel in the diets were 0, 56.5; 10, 53.5; 20, 43.5 and 30, 33.5 %, respectively. Each animal received each diet for 24 days. Daily feed intake (g/d), average daily gain (g/d), milk yield (g/d) and composition (%), feed conversion ratio (FCR) and fat – corrected milk (FCM) were determined for each cow per dietary regime. Results showed that feed intake and milk yield were not affected (P>0.05) by diets. FCM (kg) however, differed among treatments with diets A (0.21) and B (0.24) having similar (P>0.05) but higher FCM yields than diets C (0.07) or D (0.13). Milk protein (Nx6.38), butterfat (BF), total solids (TS), lactose, solids-not-fat (SNF), ash and energy contents of milk did not vary (P>0.05) significantly. Feed conversion ratio was 0.70 for diet B and this value was superior (P 0.05) negative correlation existed between milk yield and TS (r = 0.02), milk yield and BF (r = -0.04), and milk yield and milk protein (r = -0.23). Milk yield was generally poor probably due to low level of supplementation.