R. Solomon

Effect of feeding cows in early lactation with diets differing in roughage-neutral detergent fiber content on intake behavior, rumination, and milk production

This study measured the effects of including soyhulls as partial roughage replacement in total mixed rations (TMR) fed to 25 pairs of cows during early lactation, on the dry matter (DM) intake, particle kinetics, rumination, in vivo DM and NDF digestibility, milk and FCM yields, and BW changes. The 2 diets used in this study differed in the content of roughage and roughage NDF [23.5 vs. 35.0%, and 12.8 vs. 18.7% in the experimental (EXP) and control (CON) TMR, respectively]. The EXP TMR contained 20.5% less physically effective NDF than the CON TMR (11.7 vs. 14.1% of DM, respectively). These differences were expressed in a greater intake per meal (by 13.3%), a higher rate of meal intake (by 23.2%), a similar number of meals per day, a shorter daily eating duration (by 13%), and a higher total daily DMI (by 7.2%) in the EXP cows as compared with the CON cows. The in vivo DM and NDF digestibility was higher by 4.9 and 22.7%, respectively, in the EXP cows than in the CON cows. The rumination time for the TMR in the EXP cows was 12.7% (54.3 min/d) shorter than in the CON cows, and this was probably related to the difference of 12.4% in physically effective NDF intake between the 2 groups. Patterns of daily rumination and feed consumption throughout an average day showed a delay of approximately 1 to 2 h between the eating and rumination peaks. Particle flow from the rumen of the EXP cows was characterized by a longer rumen mean retention time (by 17.8%) and longer rumination time per kilogram of roughage ingested (by 23.5%) as compared with the CON cows. Thus, favorable conditions for NDF digestion were created in the rumen of the EXP cows, as reflected in their rumen pH values (6.67). The advantage of the EXP cows in intake and digestibility was reflected in a concomitant increase of 7.4% in milk production and of 9.2% in FCM yield as compared with the CON cows. No difference was found between the 2 groups with respect to efficiency of feed utilization for milk production and BW changes.

Carry-Over of Aflatoxin B1 to Aflatoxin M1 in High Yielding Israeli Cows in Mid- and Late-Lactation

The potent hepatotoxin and carcinogen aflatoxin B1 (AFB1) is a common mycotoxin contaminant of grains used in animal feeds. Aflatoxin M1 (AFM1) is the major metabolite of AFB1 in mammals, being partially excreted into milk, and is a possible human carcinogen. The maximum permitted concentration of AFM1 in cows’ milk is 0.05 μg/kg in Israel and the European Union. Since milk yield and the carry-over of AFB1 in the feed to AFM1 in the milk are highly correlated, it was considered important to determine the AFM1 carry-over in Israeli-Holstein dairy cows, distinguished by world record high milk production. Twelve such cows were used to determine AFM1 carry-over following daily oral administration of feed containing ~86 μg AFB1 for 7 days. The mean carry-over rate at steady-state (Days 3–7) was 5.8% and 2.5% in mid-lactation and late-lactation groups, respectively. The carry-over appears to increase exponentially with milk yield and could be described by the equation: carry-over% = 0.5154 e0.0521 × milk yield, with r2 = 0.6224. If these data truly reflect the carry-over in the national Israeli dairy herd, the maximum level of AFB1 in feed should not exceed 1.4 μg/kg, a value 3.6 times lower than the maximum residue level currently applied in Israel.

Effect of changing the proportion, wheat: sorghum in dairy cow rations on carbohydrate digestibility and NAN flow to the intestine

Five rumen- and abomasum-cannulated cows in mid-lactation were fed ad libitum, for two periods of 21 d each, two isonitrogenous (17% crude protein) total mixed rations (TMR) composed of 45% sorghum-wheat combination, 38% corn silage, 12% soybean meal, urea, buffers and minerals. The two TMRs differed in their sorghum (S): wheat (W) ratio, which was 7030 in S and 3070 in W treatments. Dry matter intake was 17.2 and 16.6 kg d−1 in S and W, respectively. Effect of treatments on the digestibility of carbohydrate constituents and N metabolism was examined. Neutral detergent fiber (NDF)-polysaccharides digestibility in stomachs and the entire gastrointestinal tract (GIT) was significantly higher in S than in W. The digestibility of neutral detergent soluble (NDS)-α-glucans was significantly higher in W than in S. More of NDS-α-glucans escaping ruminal fermentation was digested in the intestine of the S cows as compared with the W cows. The digestibility in entire GIT of total NDS-monosaccharide residues was 93% in W and 86% in S. Digestibility values of total carbohydrates in stomachs (49% and 52%) and entire GIT (79% and 80%) of S and W cows were similar. S and W cows were similar in rumen pH (6.15 and 6.13), rumen volatile fatty acids concentrations (133 and 136 mM) and rumen NH3 concentration (21 and 23 mg per 100 ml). Non-ammonia-N flow through the abomasum (410 and 403 g d−1) and N absorption in the intestine (67%) were also similar in S and W.

Effect of feeding ensiled mixture of pomegranate pulp and drier feeds on digestibility and milk performance in dairy cows

Based on a previous ensiling study in glass silos of various pomegranate pulp (PP) mixtures, fresh pomegranate pulp (PP) was mixed with drier feeds including soy hulls and corn silage (40:35:25 on DM basis) and ensiled in 32 pressed bales (700 kg each) wrapped with stretch polyethylene film. This ensiled pomegranate pulp mixture (PPM) was included in lactating cow total mixed ration (TMR) at a level of 20% of DM (PPM-TMR). Performance and digestion experiment was conducted with two groups of 21 milking cows each, fed individually one of the two TMR: 1. Control TMR without ensiled PPM; 2. Experimental TMR which contained 20% ensiled PPM, including 8% PP as corn grain replacer. Voluntary DM intake of cows fed the control TMR was 5.04% higher than that of the PPM cows. In vivo digestibility of DM, OM, NDF, CP and fat were significantly higher in the control cows compared with the PPM group, but methane production in the rumen fluid was 25% lower in the PPM cows. A slightly higher milk yield (by 2.2%) observed in the control cows; however, milk fat content was 5.9% higher in the PPM cows. This was reflected in similar yield of energy corrected milk (ECM) and 3.97% increase in production efficiency (ECM/DM intake) of the PPM cows compared with the control ones. Welfare of the cows, as assessed by length of daily recumbence time, was in the normal range for both groups. Body weight gain was also similar in both groups. Data suggest that the level of 8% PP in the PPM-TMR used in this study was probably too high for lactating cows and should be lowered to 4% in order to achieve better performance.

Absorption of macro- and micro-elements by sheep from barley and barley plus sulphur dioxide-treated straw rations

Abstract Sheep cannulated in the rumen, duodenum and ileum were used to study absorption of minerals from diets: I. barley only (B), and II. 70% (DM basis) barley + 30% SO2 treated wheat straw (B+S). Na and K were highly absorbed from both diets and almost completely recovered in the urine. Ca apparent absorption was low: 12.1% and 13.4% in the B and B+S treatments, respectively. The Mg net absorption in the rumen was significantly higher in diet B than in diet B+S; the difference in total tract apparent absorption of Mg was, however, much smaller and not significant: 44.5% and 38.2% for the B and B+S treatments, respectively. Animal variation in P absorption was very large, ranging from 5% to 66%. There was a trend toward net secretion of Cu, Zn and Mn in the stomachs, the trend being 2–3 times higher in the B+S than B diet. Generally, the apparent absorption of Cu, Zn and Mn was lower in the B+S than B diet; however, the most notable difference was with Cu absorption.

Ozone-treated cotton stalks as a component of a ration for growing lambs

Abstract Lambs of the Assaf dairy breed were assigned at 23–24 kg liveweight to one of three nutritional treatments: I, a high-energy concentrate mixture (CD); II, a diet in which 40% of the concentrate was replaced by a 1:1 mixture of untreated cotton stalks (CS) and poultry litter (UT-CS); III, as II, but the CS were treated with ozone gas (O 3 -TCS). The diets were fed ad libitum for 42–65 days until the lambs reached approximately 40 kg liveweight. The average daily liveweight gains were 226 g, 298 g and 395 g for the UT-CS, O 3 -TCS and CD rations, respectively. The better performance of the O 3 -TCS group of lambs, as compared with the UT-CS group, was the result of a 9.6% higher feed intake and 16.2% more efficient utilization of the diet. It was calculated that a 1:1 mixture of O 3 -treated CS and poultry litter could save 18.2% of the concentrates needed to raise lambs to 41.2 kg liveweight.

Carbohydrate digestibility and nitrogen metabolism in sheep fed untreated or sulphur dioxide-treated wheat straw and poultry litter

Digestibility of neutral detergent fibre (NDF) and monosaccharide components of diets containing 60% untreated straw (UTS) or straw treated with sulphur dioxide (TS) and poultrylitter (1:1) plus 40% concentrate at 700 g/day intake was examined in sheep equipped with rumen and duodenal cannulas. An all-concentrate diet (CD) served as a reference ration. The SO 2 treatment of straw increased the apparent digestibility of the NDF, glucose, xylose, arabinose and galactose components of the diet from 58·9, 86·7, 55·7, 82·5 and 91·8%, respectively, in the UTS diet to 73·8, 92·6, 77·8, 88·9 and 94·6%, respectively, in the TS diet. Whereas digestion of NDF and glucose in sheep on the TS diet was slightly lower than in those on the CD diet, digestion of xylose, arabinose and galactose was higher. Thus, the digestibility of total monosaccharides in th TS diet was 90·2 % and that of the CD diet only 61% units higher. The SO 2 treatment also increased the total rumen volatile fatty acid (VFA) concentration and the proportion of butyric acid in the total VFA compared with the UTS diet. Rumen ammonia concentration was 7 mg/100 ml lower and nonammonia nitrogen (NAN) flowto the duodenum was 1·3 g/day higher in sheep fed the TS diet compared with the CD diet. The quantity of duodenal N absorbed in the intestine was 10·7 g/day in the TS diet, close to the value of 11·6 g/day found with the CD diet. The similarity between the TS and CD diets in total monosaccharides digestion and duodenal Nabsorption, confirms the findings of earlier studies that a TS diet is a highly productive ration. Complementary interaction between the SO 2 -treated straw and poultry litter components of the TS diet is discussed.

The degradation and utilization of structural polysaccharides of sorghum straw by defined ruminal bacteria

Cell wall (CW) preparations of untreated sorghum straw (SORG) and sulfur dioxide-treated SORG (T-SORG) were used as substrates for the solubilization and utilization of CW carbohydrates by pure cultures or pair-combinations of defined rumen bacterial strains. Ruminococcus flavefaciens FD1 and R. albus 7 monocultures and cocultures with Butyrivibrio fibrisolvens D1 had very little solubilizing effect on SORG and even less on T-SORG CW. Fibrobacter succinogenes S85 was the best solubilizer of SORG CW components. The T-SORG CW was composed of fewer hemicellulose components and more cellulose and total CW polysaccharides than the SORG CW. Consequently, F. succinogenes S85 and BL2 monocultures and their cocultures with D1 degraded T-SORG CW polysaccharides by 21–33% units better than those of SORG CW, solubilizing 61–66% of T-SORG CW-glucose, 58–62% of CW-xylose, 58–63% of hemicellulose and 61–65% of total T-SORG structural polysaccharides. Complementary action between B. fibrisolvens D1 and the F. succinogenes strains was identified with respect to coculture growth and carbohydrate utilization, but not with respect to the extent of CW solubilization which was determined mainly by the F. succinogenes strains during 120 h of coculture incubation. In both CW substrates, utilization of solubilized cellulose by F. succinogenes S85 and BL2 monocultures was higher than that of CW-xylose and hemicellulose, being 97–98%, 53–69% and 54–75%, respectively. Under scanning electron microscopic visualization SORG CW particles were less colonized by attached bacterial cells than T-SORG. In both substrates attached F. succinogenes cells were characterized by the appearance of protuberant structures on their surface topology.