Ovarian consequences of low dose peroral Fusarium (T-2) toxin in a ewe and heifer model.

The effect of low dose peroral Fusarium produced T-2 toxin intake upon the ovarian function was evaluated in ewes (n = 30; Trial 1) and heifers (n = 7; Trial 2). Half of the ewes and all of the heifers were fed rich, acidosis-inducing concentrate. The 30 ewes were divided into 6 groups of 5 animals each. They were given 0, 0.3 or 0.9 mg/day (0, 5 or 15 ug/kg) purified T-2 toxin per os for 21 days (3x2 factorial design). Four of the 7 heifers were fed 9 mg/day (25 ug/kg) of the same purified T-2 toxin for 20 days while 3 remained untreated. The estrus cycles in all animals were synchronized prior to the trials and the T-2 exposure was started in the mid-luteal phase. The acidic condition in the rumen was estimated by the determination of urinary net acid-base excretion. The ovarian activity was followed with blood sampling for progesterone on alternate days (Trial 1) or with ultrasonography and sampling for progesterone daily (Trial 2). All of the heifers and concentrate-fed ewes showed a compensated acidosis, during first two thirds of T-2 exposure. In Trial 1, ovarian malfunction manifested as lower P4 peak concentration in the midluteal phase, shortening of the CL lifespan and prolonged follicular phases. These malfunctions were detected in 3 and 3 ewes fed concentrate and 0.3 mg and 0.9 mg T-2 toxin. Lower P4 peak concentration was observed in 1 ewe fed regular diet and 0.9 mg T-2 toxin. None of the control and acidotic groups (0 mg T-2), or ewes fed regular diet with 0.3 mg T-2 showed any ovarian malfunction. In Trial 2, after PGF2, administration the ovulation occured later and the plasma progesterone level remained low (< 3 nmol/l) for a longer period in T-2 treated heifers, than their untreated control mates (5.0+/-0.7 vs 3.7+/-0.5 d, P<0.05 and 8.3+/-0.4 vs 6.3+/-0.9 d, P<0.01, respectively). These results show that the peroral T-2 intake can significantly retard the folliculus maturation and ovulation and perhaps the subsequent luteinisation also in ruminants kept on concentrate-rich diet.

Evaluation of single cell protein from pulp mills: laboratory analyses and in vivo digestibility.

Single cell protein (SCP) derived from secondary clarifiers of pulp mills is a potential commercial protein supplement in many areas. Samples of SCP were collected from several pulp mills in the Pacific Northwest and evaluated by laboratory procedures. Six in vivo digestion trials were conducted to determine the relative nutritive value of SCP that was dewatered by centrifugation or by the addition of a polyacrylamide polymer before being put through a belt press and dried with a sonic dehydrator. Amino acid analyses showed that SCP was higher in methionine than was cottonseed meal (CSM) and had a similar level of lysine. True protein, based upon amino acids recovered in SCP samples, ranged from 51.6 to 65.9% of the crude protein (CP). Pepsin digestibility of the CP ranged from 16.2 to 36.8%. Pepsin digestibility increased by 6.3 to 11.3 percentage units when SCP were incubated in a buffered rumen fluid for 24 hours. Solubility of the nitrogenous components in 10% Burroughs' buffer solution ranged from 12.4 to 36.5%. The range in mineral composition was : P, .62 to 1.55%; Ca, .14 to .99%; K, .21 to 5.52%; Mg, .07 to .59%. The concentration of trace minerals and heavy metals varied considerably from sample to sample. Digestion trials were conducted with sheep to compare SCP with CSM; 20 to 50% of the total CP was provided by the SCP sources. The CP digestibilities of the centrifuged and the polymer-dewatered SCP were 70.5 to 70.8% and 66.3 to 69.9%, respectively, of that observed for CSM. In all digestion trials, sheep consumed the SCP diets readily, and no digestive disturbances were observed. On the basis of laboratory and in vivo results, pulp mill SCP has the potential to be a viable protein supplement for livestock.

Influence of a deficient intake of high and low degradable protein on body composition, metabolic adaptation, production and reproductive performance in early lactation dairy cows.

High-yielding dairy cows (n = 34) were divided into high (HD) and low (LD) protein degradability groups after delivery, and used for a feeding trial which lasted up to day 80 +/- 10 of lactation. The cows were regularly weighed, their body condition was scored (BCS), and their reproductive status assessed. Blood samples were taken simultaneously, and ruminal fluid was collected on the last day of the trial. On postpartum day 45 +/- 6 and 11 days thereafter two prostaglandin F2 alpha (PGF2 alpha) injections were administered. The ammonia and urea concentrations of the ruminal fluid were higher in cows of group HD. The C2:C3 ratio was 2.7:1 vs. 2.3:1 in HD and LD cows, respectively. The amino acid and lipid composition of blood reflected the dietary treatments. The BCS and blood urea concentration were slightly higher in HD animals. The average daily milk production of LD cows was 1.5 kg higher than that of HD cows. The pregnancy rates of the two groups at day 200 after calving did not differ, but LD cows showed their first visible oestrus and reconceived significantly (p < 0.05) later. It can be concluded that--at a marginal energy supply-a moderate (13%) deficiency of rumen-degradable protein during the first 10 weeks after calving can be more detrimental to reproductive performance than a severe (27%) deficiency of undegradable protein.

Effect of feeding Aspergillus oryzae fermentation extract or Aspergillus oryzae plus yeast culture plus mineral and vitamin supplement on performance of Holstein cows during a complete lactation.

The addition of Aspergillus oryzae fermentation extract (Amaferm) increased milk flow and mean 3.5% FCM production during the latter stages of the full lactation trial compared with the control group and the Aspergillus oryzae fermentation extract plus yeast culture plus mineral-vitamin supplement (VitaFerm) group. Based on the differences observed when FCM production was determined for the cows at various stages of lactation, Amaferm apparently had its greatest effect during the early stages of the lactation cycle and subsequent milk production was likely a result of higher initial production. The response difference observed between the Amaferm and VitaFerm treatments could have resulted from the additional minerals provided by the VitaFerm compared with the Amaferm and control groups.

Effect of moisture in total mixed rations on feed consumption and milk production and composition in Holstein cows.

The DM levels in total mixed rations were maintained at 62.7, 52.8, and 45.8% by incorporating 38% of the DM from alfalfa silages of twi different DM contents into the ration to determine the effect on milk production and composition when fed to lactating Holstein cows. The alfalfa silages were stored at approximately 25 and 50% DM and harvested from the same field on consecutive days either direct-cut and bagged or wilted overnight before bagging. Silages were used (minimum of 8.5 kg of Dm/d) in a total mixed ration formulated to be isonitrogenous (using cottonseed meal) and isocaloric and fed to 144 lactating cows randomly allotted into three equal groups based on days in milk (initially 33 d), lactation number, and pretrial 3.5% FCM production. Yields of 3.5% FCM were 35.3, 35.7 and 35.4 kg, respectively, for the dry, intermediate, and wet rations and were not significantly different. Consumption of DM tended to decline as DM content of the ration decreased, but the decrease was not significant. Results showed that total mixed ration moisture levels evaluated in this trial had no significant effects on consumption of DM of isonitrogenous rations or milk yield and composition.

Some blood minerals and hormones in cows fed variable mineral levels and ionic balance.

Eighty multiparous Holstein cows were assigned to eight treatments in a 2 x 2 x 2 factorial design to examine changes in serum parathyroid hormone, calcitonin, Ca, P, Mg, K, and Cl under two levels of dietary Ca and P with two anion-cation balances. Factor levels were low and high Ca (51 vs. 115 g/d), P (38 vs. 52 g/d), and cationic:anionic balance (23 vs. -8 meq). Cows were offered a TMR and an experimental mineral supplement to adjust mineral and anion-cation levels. Caudal vein blood samples were collected every 2 d from d -10 to +10 from calving. Serum K was lower for low Ca and high P compared with high Ca and low P treatments. Neither hormones nor the minerals examined in serum showed treatment effects. Cows of higher parity consumed less supplement and had lower serum Ca and P. All serum variables except calcitonin showed day to day variations. Both Ca and P decreased around parturition, whereas parathyroid hormone and Mg increased. Anionic diets did not differ from cationic diets regarding serum parathyroid hormone, calcitonin, Ca, P, Mg, K, Cl, or Na.