Evaluation of a Feed Preference Agent for Dairy Calves

A feed preference agent, Firanor-24², was added (0, 50, or 100 ppm) to whole milk and starter ration to determine if association of it with milk would enhance starter intake and weaning performance in dairy calves. Thirty 1-day-old Holstein calves (six males, four females per treatment) each received 1.6 kg of milk twice daily to 30 days of age and starter ration from 7 to 40 days of age. There were no differences from treatments in daily feed intake or body weight gains.In a paired comparison preference test for Firanor-24 in milk, two groups of five unnursed newborn calves were preconditioned to 0 or 100 ppm Firanor-24 in colostrum at birth and in milk twice daily for 6 days. In the 5-day test period each calf was offered a choice of milk with 0 or 100 ppm randomized in two adjoining buckets. No differences in milk preference were observed.     

Effects of Feeding High Magnesium to Young Dairy Calves

Holstein bull calves were fed 1, 2, and 4% supplemental magnesium as magnesium oxide. The control diet contained .3% magnesium and consisted of ground corn, soybean meal, cottonseed hulls plus mineral, vitamin, and antibiotic supplements. Diarrhea was the most obvious effect of high intake of magnesium. The extent and intensity of the diarrhea was related closely to the dietary magnesium content. High (2 and 4%) magnesium reduced feed consumption and weight gains. Although there were traces of blood in feces, no abnormalities were observed at autopsy. Large tubular sections of mucus were voided in the feces with a greater prevalance among calves fed 2 and 4% supplemental magnesium. Magnesium in plasma rose sharply in response to the increased intake of magnesium. In calves receiving the 4% added magnesium, the plasma values were triple those of controls. When high magnesium was fed, magnesium increased much more in urine than in plasma. Within 1 wk after calves were returned to control diet, magnesium in urine and plasma declined to control.     

Responses of Dairy Cows Fed Alfalfa Silage Supplemented with Phosphorus,Copper, Zinc,and Manganese

Thirty-three Holstein-Friesian cows (21 multiparous, 12 uniparous) were allocated randomly to three treatments 14 wk prepartum and fed through 22 wk postpartum. Each cow individually was fed alfalfa silage to 2%, dry matter, of body weight and high moisture grain corn to exceed National Academy of Sciences-National Research Council recommendation for energy by 10% and soybean meal to meet that for protein. The basal diet was supplemented with phosphorus, copper, zinc, and manganese to supply either 100%, 150%, or 200% of recommendations for these minerals. A trend for increased dry matter intake and decreased total milk yield caused a slight linear decrease in yield/intake with increased mineral supplementation. However, milk protein percentage increased linearly with increased mineral supplementation, and lactose and fat were unaffected. No reproductive traits differed. There was, however, a trend for cows supplemented with minerals at 200% recommendations to have fewer days to first estrus. Inorganic phosphorus in blood increased linearly with increased mineral supplementation as did retentions of all supplemented minerals. No effects on lactational or reproductive performance were adverse in cows fed alfalfa silage (1.27% calcium, 16.5% crude protein, dry matter basis) as the sole forage. Therefore, supplementation with phosphorus, copper, zinc, and manganese above recommendations may be necessary only when alfalfa silage contains more than 1.5% calcium.     

No Associative Effects Between Corn and Haycrop Silages Fed to Lactating Dairy Cows

Four first-lactation Holstein cows were used 65 to 177 days postpartum in a 4 × 4 Latin square trial to evaluate possible associative feeding effects between corn and haycrop silages. Nutrient digestibility and nitrogen and energy balances were studied. Diets were concentrate mixture, urea-treated corn silage, and early-cut, wilted haycrop silage in dry matter ratios of 55:45:0, 55:30:15, 55:15:30, and 55:0:45. Rations were offered just below energy balance in each 28-day period. Ration components were fed separately, concurrently, and twice daily. Crude protein in concentrate, corn silage, and hay crop silage dry matter was 16.9, 11.1, and 12.5%. Milk yield (18 to 19 kg) and ration dry matter intake (2.61% body weight) were not significantly different among diets. Apparent digestibility of gross energy, dry matter, protein, and fiber was not different among diets, but fat was more digestible in corn silage. Partition of ingested energy and nitrogen was not affected by treatments except that urine nitrogen was higher in corn silage. No associative feeding effects were significant. The two silages were equivalent in supporting milk production when fed in equal dry matter amounts.     

磷钒钼黄光度法测定磷含量的测量不确定度评定

用国际通用的方法评估出磷钒钼黄光度法测定磷含量的测量不确定度,考虑不确定度的主要来源包括仪器的精密度、标准物质标称值的不确定度以及制备溶液过程中引起的不确定度,推导出各种传播系数表达式,计算出各种不确定度分量并将其合成,以测定钢铁中磷含量为例,提供计算过程所需的各参数的采集和计算方法。     

中国荷斯坦奶公犊不同部位肉的品质特性

为分析比较中国荷斯坦奶公犊不同部位肌肉品质间的差异,选取6 头遗传背景一致、7 月龄左右的荷斯坦奶公犊,经商业屠宰厂宰后排酸48 h。分别采集6 个部位（外脊、半腱肌、半膜肌、股内侧肌、股直肌和股外侧肌）的肌肉样品,测定其营养成分、理化指标及感官品质,并利用主成分分析法研究犊牛肉品质性状之间的关系。结果表明：半膜肌中蛋白质含量显著高于股内侧肌（P＜0.05）,股内侧肌水分含量和红度值最高,但嫩度最差（P＜0.05）,股直肌的滴水损失最大（P＜0.05）,外脊和半腱肌具有更低的红度值（P＜0.05）,外脊与股直肌总体可接受性评分显著高于股外侧肌（P＜0.05）;主成分分析结果表明,感官特性因子、持水力因子和营养成分因子累计贡献率达59.79%,可基本反映6 个部位犊牛肉的品质评价信息。综上所述,奶公犊不同部位肉间的各指标差异较大,可依据各部位肉的典型特征提升奶公犊部位肉的市场价值,达到优质优价的市场效果。     

Nutrient Content of Special Fed Veal Ribeyes

The nutrient content of special fed veal (SFV) was analyzed and compared to previously reported values for veal and beef. Ribeyes of SFV from 8 different U.S. producers were analyzed for moisture, total fat, protein, cholesterol, folacin, thiamin, riboflavin, niacin, B₆, B₁₂, vitamin A, pantothenic acid, 16 amino acids and 8 minerals. Special fed veal was found to be similar in nutrient content to reported values for beef and veal with one exception; the Fe content of SFV was 14–25% of reported values for beef.     

Performance of Calves Fed Milk Replacer Once Daily at Various Fluid Intakes and Dry Matter Concentrations

Ninety-six Holstein calves were fed 1 of 12 liquid diets once daily under two feeding options. Diets consisted of milk replacer (22% crude protein, 10% fat) fed at fluid intakes of 6, 8, and 10% body weight and dry matter concentrations of 10, 13, 16, and 19%. Feeding options consisted of calculating fluid intake and dry matter concentration based on initial weight and holding this constant through weaning or adjusting weekly according to change in body weight. Water and a complete calf starter (minimum 15% crude protein) were available ad libitum. Calves were weaned abruptly at 4 wk of age and observed until 6 wk of age for immediate postweaning performance. Fluid intake and dry matter concentration had a positive effect on weight gain during wk 0 to 4. However, during the immediate postweaning period, gain decreased in calves previously fed replacer at the higher intake. Overall gain (wk 0 to 6) was not affected by fluid intake or dry matter concentration. Starter intake decreased with increasing fluid intake or dry matter concentration during wk 4 and wk 0 to 4. Total intakes of dry matter were not affected by treatment. Incidence of scours increased linearly with dry matter concentration, and both fluid intake and dry matter concentration had a positive linear effect on fecal score and duration of scours. Feeding option had no effect on any measures. Calves fed replacer containing between 10 and 13% dry matter and offered at 8% body weight had fewer intestinal disturbances during the replacer feeding period and obtained recommended gains over the entire 6 wk.     

磷素水平对甜菜生育及产质量的影响

磷能促进甜菜根系发育，施磷能显著地增加须根的干物重、长度和表面积，施磷量与须根干物重呈显著正相关，r=0.999**。施磷量与块根产量呈显著正相关,r=0.904*。在本试验土壤条件下，磷肥对块根含糖率没有明显的影响。     

Adrenal Response During Periparturient Period to Adrenocorticotropin in Dairy Cattle Fed Corn Silage and Grass Legume Silage

Glucocorticoid response to exogenous adrenocorticotropin was used as an indicator of stress in cows fed different diets ad libitum during the dry period and throughout lactation. Twenty-three Holstein cows were administered adrenocorticotropin at 2 d after initiation of the dry period and at 2 d and 35 d postpartum, and plasma glucocorticoid response was evaluated. Cows were fed diets using only corn silage as forage or mixed forage with or without supplemental concentrate. Mean basal plasma glucocorticoid concentrations were 6.1 ng/ml on d 2 after dry off, 4.7 ng/ml on d 2 postpartum, and 6.7 ng/ml on d 35. Cows on the 32.5:32.5:35 corn silage:grass-legume silage:concentrate diet had the lowest basal glucocorticoid concentrations on d 2 postpartum but highest concentrations on d 35 of lactation. Mean glucocorticoid response was 33.2 ng/ml on d 2 of lactation compared with 50.6 ng/ml on d 35 and 48.5 ng/ml plasma on d 2 following drying off. Diet interactions suggest that feed components may be involved with ability to tolerate stresses that occur during lactation and the dry period and thus may lead to altered adrenal function.     

Supplementation of Copper as Copper Sulfate or Copper Proteinate for Growing Calves Fed Forages Containing Molybdenum

Holstein calves (age > 12 wk old) were assigned to dietary treatments of 1) no supplemental copper, 2) copper proteinate, or 3) copper sulfate. The copper supplements were incorporated into premixes and added to a pelleted concentrate. The concentrates were fed at 1.8 kg per head per d and contained 5, 19, or 19 ppm copper and .6 ppm molybdenum by analysis. All calves were fed a grass hay free-choice, which contained 1 ppm copper and 5 ppm molybdenum. Ratios of copper to molybdenum were .9, 2.8, and 2.8 for diets 1, 2, and 3, respectively. Copper concentrations in plasma were significantly greater at wk 12 in calves fed copper proteinate than control or calves supplemented with copper sulfate. Liver copper also was higher at wk 12 in calves fed copper proteinate. Final body weights, plasma zinc, plasma iron, hemoglobin, and hematocrit were not affected by treatment. Bioavailability of dietary copper from copper proteinate was greater than from copper sulfate for calves fed diets containing molybdenum.     

奶牛饲料中磷需求量研究进展

反刍类动物如奶牛饲料中需要添加一定量的磷以供动物瘤胃中的微生物生长和代谢,但现行标准中推荐的磷的添加量高于奶牛对磷的实际生理需求量。饲料中添加过量的磷不但增加了饲料成本,而且造成了环境污染。文章对美国、法国、荷兰等奶牛养殖先进国家关于奶牛饲料中磷需求量的最新试验研究成果进行了分析对比,介绍了现行奶牛饲料标准中磷的添加量可以降低的新模式,并且强调了奶牛饲料中应用谷物配料时应该注意的实际问题。