Fermentation substrate and dilution rate interact to affect microbial growth and efficiency

The effect of dilution rate (D) on carbohydrate, fibrous and nonfibrous, and protein fermentation by ruminal microorganisms was studied using a single-effluent continuous-culture system. The diets of fibrous carbohydrate, nonfibrous carbohydrate, or protein were formulated with soybean hulls (FC), ground corn (NFC), or isolated soy protein (PR) as the primary ingredient, respectively. Six dilution rates (.025, .050, .075, .10, .15, and .20/h of fermenter volume) were used. Digestibilities of DM, OM, and CP for the three diets and of NDF and ADF for the FC diet decreased (P<.001) as D increased, although the response of the digestibility to D varied with diet. Increasing D resulted in an increase in pH (P<.001) and a decrease (P<.001) in ammonia concentration. Daily volatile fatty acid production increased (quadratic; P<.01) for the FC and NFC diets, but decreased (quadratic; P<.001) for the PR diet. Increasing D quadratically increased (P<.001) the molar percentage of acetate and propionate, but quadratically decreased (P<.001) butyrate and valerate for the FC and NFC diets. For the PR diet, the molar percentage of propionate and valerate increased (quadratic; P<.01), whereas acetate and butyrate decreased (linear; P<.001) in response to increasing D. Molar percentage of isobutyrate and isovalerate decreased (P<.01) with increasing D for all three diets. As D increased, daily microbial N production showed quadratic responses with maximum values achieved at .126, .143, and .187/h D for the FC, NFC, and PR diet, respectively. There was a positive correlation between microbial growth efficiency (MOEFF) and D. A quadratic model fit the data of MOEFF as affected by D, and maximum MOEFF of 37.3, 59.6, and 71.4 g of bacterial N/kg OM truly fermented were calculated to be achieved at .177, .314, and .207/h D for the FC, NFC, and PR diet, respectively. Dilution rate significantly influenced the ruminal microbial fermentation of fibrous and nonfibrous carbohydrates and proteins, and was positively related to microbial yield and growth efficiency. In addition, microbial nitrogen composition, and therefore efficiency, was affected by substrate fermented.     

Effects of L-carnitine fed during lactation on sow and litter performance

Sows of differing parities and genetics were used at different locations to determine the effects of feeding added L-carnitine during lactation on sow and litter performance. In Exp. 1, sows (n = 50 PIC C15) were fed a lactation diet (1.0% total lysine, .9% Ca, and .8% P) with or without 50 ppm of added L-carnitine from d 108 of gestation until weaning (d 21). No differences in litter weaning weight, survivability, sow ADFI, or sow weight and last rib fat depth change were observed. Number of pigs born alive in the subsequent farrowing were not different (P>.10). In Exp. 2, parity-three and -four sows (n = 115 Large White cross) were used to determine the effect of feeding 0, 50, 100, or 200 ppm of added L-carnitine during lactation (diet containing .9% total lysine, 1.0% Ca, and .8% P) on sow and litter performance. No improvements in the number of pigs or litter weights at weaning were observed (P>.10). Sows fed added L-carnitine had increased weight loss (linear; P<.04), but no differences (P>.10) were observed in last rib fat depth change or subsequent reproductive performance. In Exp. 3, first-parity sows (n = 107 PIC C15) were fed a diet with or without 50 ppm of added L-carnitine during lactation (diet containing 1.0% total lysine). Sows fed added L-carnitine tended (P<.10) to have fewer stillborn and mummified pigs than controls (.42 vs .81 pigs). No differences were observed for litter weaning weight, survivability, or subsequent farrowing performance. Feeding 50 to 200 ppm of added L-carnitine during lactation had little effect on sow and litter performance.     

Teratogenic effects of chronic ingestion of high levels of vitamin A in cats

High concentrations of retinoids occur in some commercial cat food formulations as a result of the use of animal liver as an ingredient. Our objective was to study the teratogenic potential of dietary vitamin A in cats. We investigated the incidence of birth defects in kittens of queens given diets with retinyl acetate concentrations of 6000, 306000, or 606000 retinol equivalents (RE)/kg diet (control, 306K, or 606K groups, respectively) for approximately 3 years [1 RE=1 micro g retinol=3.3 International Units (IU)]. Each group comprised 12-15 age-matched, nulliparous domestic short-haired queens that were exposed to toms. There were a total of 396 kittens born in 97 litters. Pregnancy rate, number of kittens per gestation and gestations per year were not significantly different among treatment groups. A total of 2, 5 and 11 malformed kittens occurred in the control, 306K and 606K groups, respectively. Malformations included cleft palate, cranioschisis, foreshortened mandible, stenotic colon, enlarged heart and agenesis of the spinal cord and small intestine, which are typical foetal defects consistent with ingestion of excess retinoids in other species. This study demonstrated that a concentration of 306000 RE/kg diet has a potential for causing birth defects in the kittens.     

Graft-versus-host reaction (GVHR) in clonal amago salmon,Oncorhynchus rhodurus

The graft-versus-host reaction (GVHR) was demonstrated in a salmonid model system of clonal diploid and triploid amago salmon. Triploid operculum grafts on clonal diploid evoked an acute rejection within 12 days. Grafts exchanged among triploid amago salmon exhibited prolonged survival for 18 days. In contrast, diploid grafts on triploid, and allografts among clonal diploid amago salmon were accepted. A typical GVHR was induced in triploid recipients by intraperitonal injection of head kidney cells from sensitised diploid donors. The clinical signs of graft-versus-host disease (GVHD) were observed in the recipients after 1 week of cell injection as a loss of appetite and appearance of solid faeces, followed by haemorrhage, local swelling of ventral skin and an enlarged spleen. Three of six fish died within 1 month. Water temperature and frequency of sensitisation are critical to induce GVHR. Diploid donors had to be sensitised three times at 20 degrees C to induce the typical GVHR. GVHR was most effectively induced by head kidney cells, followed by peripheral blood leucocytes (PBL) and spleen cells. Ploidy analysis by flow cytometry revealed that the donor head kidney cells greatly increased in the recipient liver, head kidney and spleen, and reached the peak after 9 days of donor cell injection. The results in the present study are quite similar to the findings in ginbuna and ginbuna-gold fish hybrid system, suggesting the presence of T cells in salmonid as well as cyprinid fish.