Forty-four Holstein calves (19 male and 25 female) were used in this study of the relationships among age at first colostrum feeding, IgG intake, and apparent efficiency of IgG absorption. Time of birth was recorded for each calf and the calves were fed colostrum ad libitum after birth at either 0930 or 1630 h. Blood samples were collected immediately before and 24h after colostrum feeding. Data from calves were then categorized into 4 groups representing time from birth to colostrum feeding: A=fed within 1h (n=5); B=fed from 1 to 6h (n=10); C=fed from 6 to 12 h (n=21); and D=fed from 12 to 18 h (n=8) after birth. Average total intake of colostrum was 3.6 ± 0.1L. Over 80% of the calves consumed ≥3 L of colostrum. Apparent efficiency of IgG absorption declined remarkably 12 h after birth. Mean apparent efficiency of absorption of IgG in group D (15.8 ± 3.0%) was lower than that in groups A (30.5 ± 3.9%) and B (27.4 ± 2.8%). Serum IgG concentration in calves was positively correlated with IgG intake in all groups. The relationship between mass of IgG consumed and calf serum IgG at 24 h was different for each time of colostrum feeding, with only limited differences observed between groups A and B. We concluded that failure of transfer of passive immunity in newborn calves may be avoided if calves consume ≥3 L of colostrum with IgG concentration >40 mg/mL within 6 h after birth. These findings help define the opportunity to minimize failure of transfer of passive immunity to newborn calves under management programs similar to those used on commercial dairy farms.
Twenty-eight primiparous sows were used to determine the effect of litter size on the growth of mammary glands and nursing pigs during lactation. Litter size was set to 6, 7, 8, 9, 10, 11, or 12 pigs by cross-fostering immediately after birth. Four sows were allotted to each litter-size group. Sows were allowed to consume a daily maximum of 13.6 Mcal ME and 46.3 g of lysine during lactation. Sows were slaughtered on d 21 (20.6+/-1.1) of lactation. Mammary glands were collected at slaughter and trimmed of skin and the extraneous fat pad. Each gland was separated, weighed, and ground for chemical analysis. Dry matter, dry fat-free tissue (DFFT), crude protein, ash, and DNA contents were measured. Only glands known to have been nursed were included in the data set. Wet and dry weights and the amounts of DFFT, protein, DNA, ash, and fat in individual nursed mammary glands linearly decreased (P<.05) as litter size increased. Percentages of DFFT, protein, and DNA were quadratically affected (P<.05) by litter size on d 21 of lactation. Total mammary wet and dry weights and total DFFT, protein, DNA, fat, and ash amount of all nursed mammary glands of each sow were increased as litter size increased (P<.05). Changing litter size from 6 to 12 pigs resulted in 2,098, 432, 253, 227, 4.4, 178, and 20 g increases in the amounts of total mammary wet weight, dry weight, DFFT, protein, DNA, fat, and ash, respectively, on d 21 of lactation. Litter weight gain was 18.1 kg greater in sows with 12 pigs than in sows with 6 pigs. Sows with a larger litter size had a greater increase in total mass of mammary gland tissue and litter weight but had lower growth of individual nursed mammary glands and individual pigs than sows with the smaller litter size. The need for nutrients to support additional mammary gland and litter growth as litter size increases should be considered when estimating nutrient requirements for lactating sows. Sows need an additional .96 g lysine per day to account for mammary gland growth for each pig added to a litter.
. Effect of mechanical processing of corn silage on in vitro ruminal fermentation, and in situ bacterial colonization and dry matter degradation. Can. J. Anim. Sci. 87: 259-267. Rumen fermentation and bacterial colonization of mechanically processed corn silage were evaluated in a series of in vitro and in situ experiments using ruminally cannulated cows. Data from rumen-simulated continuous culture (Rusitec) showed that total VFA concentration was increased (P < 0.001) by feeding processed corn silage, while pH was reduced (P < 0.001) and ammonia nitrogen remained unchanged (P > 0.05). Mechanical processing enhanced the in situ rate and extent of dry matter disappearance for corn stems and kernels, respectively (P < 0.05). It also enhanced in situ, the initial attachment of rumen bacteria responsible for corn digestion, as monitored by real-time PCR. The16S rDNA copy numbers of amylolytic and lipolytic bacteria, such as Succinivibrio dextrinosolvens, Ruminobacter amylophilus and Anaerovibrio lipolytica, attached to corn kernels were increased for processed corn silage (P < 0.05), in particular at 2 h after the start of incubation. In addition, corn stemattached cellulolytic and hemicellulolytic bacteria, such as Fibrobacter succinogenes, ruminococci and Eubacterium ruminantium, increased in 16S rDNA copy numbers for processed corn silage (P < 0.05). This was observed for the initial incubation period from 10 min to 2 h. These results demonstrate more rapid attachment and heavier colonization of rumen bacteria to the processed compared with the unprocessed silage, which facilitates ruminal digestion and fermentation.Key words: Corn silage, mechanical processing, rumen fermentation, bacteria, attachment Kozakai, K., Nakamura, T., Kobayashi, Y., Tanigawa, T., Osaka, I., Kawamoto, S. et Hara, S. 2007. Incidence du conditionnement mécanique sur la fermentation in vitro de l'ensilage de maïs dans le rumen ainsi que sur sa colonisation par les bactéries et la dégradation de la matière sèche in situ. Can. J. Anim. Sci. 87: 259-267. Les auteurs ont étudié la fermentation de l'ensilage de maïs conditionné mécaniquement et sa colonisation par les bactéries du rumen dans le cadre d'une série d'expéri-ences in situ et in vitro en recourant à des vaches canulées au rumen. Les données issues des cultures continues simulant le rumen (Rusitec) montrent que le conditionnement de l'ensilage augmente la concentration totale d'acides gras volatils (P < 0,001) tout en réduisant le pH (P < 0,001), sans modification de la concentration d'azote ammoniacal (P > 0,05). Le conditionnement mécanique accroît le taux de disparition in situ de la matière sèche et la quantité totale de matière sèche dégradée, respectivement pour les rafles et les grains de maïs (P < 0,05). In situ, il améliore aussi la fixation initiale des bactéries du rumen responsables de la digestion du maïs, telle que suivie par PCR en temps réel. On note une hausse du nombre de copies de l'ADNr 16S des bactéries amylolytiques et lipolytiques comme Succinivibrio dextrinos...
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