A study was conducted on the use of a partial total mixed ration (pTMR) on 13 pasture-based dairy farms in New York and Pennsylvania. The objectives of the study were to monitor and summarize management decisions made in relation to pTMR formulation throughout the grazing season and to develop recommendations for use of a pTMR in a pasturebased system. In general, haylage or silage replaced pasture in the pTMR diet. The pTMR protein level was often decreased with high pasture protein content; however, total dietary protein still exceeded protein requirements by an average of 39% over NRC requirements on most farms. In some cases, nutritionists or producers underestimated the nutritional quality of pasture. All farms appeared to be feeding adequate levels of energy in relation to NRC requirements. Few farms analyzed pastures for nutrient content, even though forage testing of stored forages was common. The amount of pTMR fed was frequently adjusted on most farms based on bulk milk tank readings, changing pasture availability, and pTMR refusal rates. Outside factors (i.e., water supply on pasture, heat, time on pasture, pasture condition) also have significant impacts on animal productivity and health and must be considered in a whole-farm approach. Flexibility is key in utilizing a pTMR on pasture-based operations to respond to changing pasture quality and quantity and to formulate least-cost rations. The basic principles of nutrition still apply — monitor dry matter intake, forage to concentrate ratios, and milk production.

Sward composition and structure influence herbage intake of grazing animals. We conducted a grazing study to examine how forage mixture complexity affected sward structure. Replicated 1‐ha pastures (Hagerstown silt loam soil: fine, mixed, semiactive, mesic, Typic Hapludalf) were planted to either orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.) or a nine‐species mixture [orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), white clover, alfalfa (Medicago sativa L.), and chicory (Cichorium intybus L.)]. Pastures were stocked rotationally with lactating dairy cows (Bos taurus). Herbage mass, sward height, vertical structure, and nutritive value were measured pre‐ and postgrazing during four periods in each of 2002 and 2003. Pregrazing sward height was similar between the mixtures. Pregrazing herbage mass and sward bulk density were 30% less in the two‐species mixture than the nine‐species mixture in 2002 but similar in 2003. The nine‐species mixture had more herbage dry matter in the upper sward layers than the two‐species mixture. Bulk density of herbage dry matter increased and nutritive value decreased from the top to the bottom of both swards. Cattle grazed deeper into the two‐species sward (18 cm) than the nine‐species mixture (11 cm) in 2003; however, individual botanical components in the upper 25 cm of the canopy were removed similarly between treatments. We conclude that sward structure did not alter the pattern of herbage removal during grazing of simple or complex swards.

Twenty multiparous Holstein cows in midlactation grazed pastures of 4 forage mixtures in a 12-wk study repeated during 2 grazing seasons to determine if forage mixture complexity affected intake and productivity of lactating dairy cows. The forage mixtures were 1) orchardgrass plus white clover [2 species (SP)]; 2) orchardgrass, white clover, and chicory (3SP); 3) orchardgrass, tall fescue, perennial ryegrass, red clover, birdsfoot trefoil, and chicory (6SP); and 4) 6SP mixture plus white clover, alfalfa, and Kentucky bluegrass (9SP). Total herbage intake was similar among forage mixtures, averaging 12.0 kg/d across all forage mixtures and years. Milk production and composition were not affected by forage mixture or year, and averaged 34.6 kg/d, 3.4%, and 2.8% for milk production, milk fat percentage, and milk protein percentage, respectively. The conjugated linoleic acid content of milk fat was higher for cows that grazed the 3SP, 6SP, and 9SP mixtures than from cows that grazed the 2SP mixture (1.02 vs. 0.87 g of conjugated linoleic acid/100 g of fatty acids, respectively). Blood glucose, blood urea nitrogen, and nonesterified fatty acids were not affected by forage mixture and averaged 69.2 mg/dL, 13.4 mg/dL, and 277.5 muEq/L, respectively. The results of this study indicate that altering the forage mixture in pastures did not affect dry matter intake, milk production, or blood metabolite profiles of lactating cows. The use of complex mixtures of forages in grazing systems should not affect dairy cow performance.

A survey of 38 universities that grant 4-yr degrees as well as 12 institutions that grant technical degrees of 2 yr or less revealed that degree programs in dairy production remain popular, but have changed significantly over the last 25 yr. Enrollment in dairy production programs remains strong (1,189 and 417 students in baccalaureate and nonbaccalaureate degrees, respectively) even though this is viewed as a traditional industry. There are significant differences in size of programs across the United States, and some are struggling to maintain both the visibility and faculty numbers to keep pace with the industry. The percentage of students enrolled in 4-yr programs who are female has increased to the majority. More students hail from a nondairy farm background in our university programs today than in 1994. Computer and information technology has become a mainstream part of our educational programs. A high percentage of undergraduate students elect to engage in an internship or work experience, and there is a high correlation between internship and career paths selected by our students. The dairy industry initiated and financially supports the North American Intercollegiate Dairy Challenge; an educational activity among university teams to foster skills in analyzing a dairy farm business. This collaboration between universities and private industry is strong evidence that our undergraduate programs are relevant to the dairy industry. Extracurricular activities like dairy science clubs also remain popular, and are perceived by faculty members to be an important part of our educational experience. An analysis of nonbaccalaureate degree programs was not reported previously, but was a part of the present survey. In the nonbaccalaureate institutions that responded to the survey, there were 417 students enrolled in 12 dairy programs across the United States in 2004. This student population in nonbaccalaureate programs has a higher percentage of female enrollment than in 1994, but enrollment is still predominantly male. Computer and information technologies are an important part of their curricula and a very high percentage of these students remain in production agriculture upon graduation. Many of the challenges in undergraduate education described previously continue to be challenges in 2005. However, there are many reasons for optimism; as the number of students electing enrollment in dairy production remains strong, there is great interest in keeping the curricula relevant and interaction with and support by the dairy industry continues to be significant.

The results of 14 research studies indicated that grazing dairy cows fed monensin respond similarly in milk yield and milk composition to dairy cows fed in confinement. When compared to controls, grazing cows receiving monensin averaged 0.9 kg/cow per d greater milk production. Milk fat percent was 0.1% less and milk protein percent was 0.05% less; however, daily yield of milk fat and milk protein were slightly greater for grazing cows fed monensin compared with controls. Results from a study in which pasture was supplemented with a partial total mixed ration (TMR) suggest the effects of feeding monensin pre-calving carry over post-calving in early lactation. Feeding monensin increased yields of milk and protein without affecting 3.5% fat-corrected milk production, reduced the loss of body condition score, and improved percentage of pregnancy. The effects of monensin may be related to an improved energy balance of lactating dairy cows fed pasture supplemented with a TMR. Monensin was initially approved for dairy cows in the United States only when included in a TMR. Monensin is now approved for component feeding systems in which cows are fed in a tie stall barn or milking parlor, or as a top dress, and thus can be fed to dairy cows on a grazing system.

Forty-five Holsteins cows in early to mid-lactation were used to evaluate the milk fatty acid composition of three feeding systems that combined pasture and total mixed ration (TMR) in a 19-week experiment. The three treatments were: (1) pasture plus concentrate (PC), (2) pasture plus TMR (PTMR), and (3) TMR. The content of short- and medium-chain fatty acids (FA) decreased from 11.3 to 9.0g/100g of FA and from 40.5 to 36.5g/100g, respectively, from the TMR to the PC treatment. The content of long-chain FA increased from 47.7 to 53.8g/100g as the amount of pasture dry matter (DM) intake increased from the TMR to the PC treatment. The content of saturated FA was lower (55.5g/100g versus 60.1g/100g) and the content of unsaturated FA was higher (43.9g/100g versus 38.6g/100g) in the PC treatment versus the PTMR and TMR treatments. As the amount of pasture DM intake increased from the TMR to the PC treatment, the content of conjugated linoleic acid (CLA) increased from 0.59 to 1.21g/100g, resulting in a 42 and 105% increase for the PC treatment compared to the PTMR and TMR treatments, respectively. The increase in CLA content in milk with inclusion of pasture was primarily associated with a higher intake of C18:3 and a higher delivery of trans11 C18:1 to the mammary gland.

The results of 14 research studies indicated that grazing dairy cows fed monensin respond similarly in milk yield and milk composition to dairy cows fed in confinement. When compared to controls, grazing cows receiving monensin averaged 0.9 kg/cow per d greater milk production. Milk fat percent was 0.1% less and milk protein percent was 0.05% less; however, daily yield of milk fat and milk protein were slightly greater for grazing cows fed monensin compared with controls. Results from a study in which pasture was supplemented with a partial total mixed ration (TMR) suggest the effects of feeding monensin pre-calving carry over post-calving in early lactation. Feeding monensin increased yields of milk and protein without affecting 3.5% fat-corrected milk production, reduced the loss of body condition score, and improved percentage of pregnancy. The effects of monensin may be related to an improved energy balance of lactating dairy cows fed pasture supplemented with a TMR. Monensin was initially approved for dairy cows in the United States only when included in a TMR. Monensin is now approved for component feeding systems in which cows are fed in a tie stall barn or milking parlor, or as a

Milk fatty acid (FA) composition of dairy cows from two grazing studies was examined. In the first study, effects of concentrate supplementation and pasture allowance were evaluated using 20 multiparous Holstein cows in five 4×4 Latin squares. The four treatments resulted from the combination of two pasture allowances (i.e., low, 25 versus high, 40kg dry matter/cow/day) and two concentrate supplementation levels (i.e., 0 versus 1kg concentrate/4kg milk). No interactions occurred between concentrate supplementation and pasture allowance for milk FA composition. Concentrate supplementation increased short-chain FA content, and reduced the content of long-chain FA, trans11 C18:1, and cis9, trans11 conjugated linoleic acid (CLA) (1.36 versus 1.18g/100g). Concentrate supplementation increased saturated FA (58.6 versus 54.0g/100g) and reduced unsaturated FA content (39.9 versus 43.8g/100g). Grazing at high pasture allowance increased short-, medium-, and long-chain FA content, without affecting cis9, trans11 CLA content. Saturated FA content was higher (57.1 versus 55.6g/100g), and unsaturated FA content was lower (41.3 versus 42.5g/100g), when cows grazed at high pasture allowance. Concentrate supplementation reduced unsaturated FA and cis9, trans11 CLA in milk of dairy cows grazing at two pasture allowances. In the second study, two experiments evaluated effects of different energy supplements in grazing dairy cows. In Experiment 1, 25 multiparous Holstein cows were assigned to a cracked corn (CC) or a steam flaked corn (SFC) supplement containing 667g/kg of corn grain plus a pelleted protein/mineral supplement. In Experiment 2, 22 multiparous Holstein cows were assigned to a ground corn grain (GC) or a non-forage fiber (NFF) supplement. The GC supplement contained 850g/kg of corn grain, and the NFF supplement contained 440g/kg of non-forage fiber sources (i.e., beet pulp, soyhulls, wheat middlings) that partially replaced corn grain. Milk FA composition was not affected by corn processing or carbohydrate source. The content of short-, medium-, long-chain FA, and cis9, trans11 CLA (2.5g/100g in Experiment 1; 2.1g/100g in Experiment 2) was similar between supplements in both experiments. The type of supplement did not affect the content of saturated (62.6g/100g in Experiment 1; 65.4g/100g in Experiment 2) and unsaturated FA (37.5g/100g in Experiment 1; 34.6g/100g in Experiment 2). Supplementation with supplements differing in the rate and extent of ruminal carbohydrate digestion did not affect the milk FA composition of grazing dairy cows.

Some producers believe that planting pastures to several forage species benefits sustainability of grazing systems. We conducted a grazing study to determine if forage species diversity in pastures affects herbage productivity and weed invasion. One‐hectare pastures were planted to four mixtures in August 2001 and then grazed with lactating dairy cattle during 2002 and 2003. The mixtures were two species [orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.)], three species [orchardgrass, white clover, and chicory (Cichorium intybus L.)], six species [orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), and chicory], and nine species [the six‐species mixture plus white clover, alfalfa (Medicago sativa L.), and bluegrass (Poa pratensis L.)]. When rainfall was plentiful (2003), there were no differences in herbage yield among the mixtures; all averaged 9800 kg ha−1 dry matter. During 2002, which was dry, the two‐species mixture produced less herbage than the other mixtures (4800 vs. 7600 kg ha−1 dry matter). The proportion of nonsown species in the sward was lower for the six‐ and nine‐species mixtures than the two‐and three‐species mixtures, indicating less weed invasion for these complex mixtures. Red clover and chicory proportions decreased by 80% after 2 yr, and orchardgrass dominated in all pastures by May 2004. We conclude that planting a mixture of grasses, legumes, and chicory will benefit herbage production during dry years and will reduce weed invasion for a few years after planting under management similar to ours. Producers would have to reestablish the chicory and legume components relatively frequently to maintain these benefits.

Grazing behavior of Holstein cows in late lactation at 2 pasture allowances without or with supplementation was studied in a single reversal design. Twenty multiparous cows (4 ruminally cannulated) grazed a bromegrass/orchardgrass pasture offered at 2 pasture allowances: 1) low, and 2) high, with 25 and 40 kg/d of DM per cow, respectively. Half of the cows were supplemented with a mineral/vitamin mixture (1 kg/ d of the mix in a corn/molasses carrier) and the other half supplemented with a corn-based concentrate (1 kg of concentrate per 4 kg of milk). Automatic behavior recorders were used to measure grazing time and number of bites. For the mineral/vitamin mixture-supplemented cows, grazing time and number of bites after the p.m. milking was greater and ruminal pH was numerically lower at the high pasture allowance. For the concentrate-supplemented cows, grazing behavior and ruminal pH did not differ between the 2 pasture allowances. Pattern of grazing time of mineral/vitamin mixture-supplemented and concentrate-supplemented cows influenced daily oscillations of ruminal pH and NH3-N concentration. Pasture allowance affected grazing behavior of mineral/vitamin mixture-supplemented cows; however grazing behavior of concentrate-supplemented cows was not affected by pasture allowance.

Twenty multiparous Holstein cows were used in a completely randomized design with repeated measures to study milk production of cows supplemented or not supplemented with concentrate when they were switched to a total mixed ration (TMR) after grazing. In one group, cows grazed an or-chardgrass/bromegrass pasture and were assigned to one of two treatments: 1) unsupplemented (U; 1 kg/d mineral mix) or 2) concentrate supplemented (CS; 1 kg corn-based concentrate/4 kg milk). Total DMI was greater (26.5 vs 22.0 kg/d), but pasture DMI was less (16.8 vs 21.2 kg/ d), for CS cows because of the substitution rate of 0.49 kg pasture/kg concentrate. Overall, CS cows had greater 3.5% fat-corrected milk (FCM) (32.9 vs 26.5 kg/d), but less milk urea N (MUN; 9.6 vs 14.7 mg/dL) and milk fat (3.13% vs 3.88%), than U cows. Milk response to supplementation averaged 1.08 kg milk/kg concentrate. Cows assigned to both treatments lost BW (-17 kg/d) and body condition score (BCS) (-0.33). At the end of the 6-wk grazing period, all cows were switched to a TMR fed in confinement for 11 wk. Overall, DMI (24.3 kg/d), 3.5% FCM (30.6 kg/d), milk fat (3.26%), milk true protein (2.87%), and MUN (12.7 mg/dL) did not differ between treatments. Cows gained BW (53 kg) and BCS (0.33). A significant treatment × time interaction was found for milk yield. During the first day of TMR feeding, milk yield was greater (30.9 vs 19.3 kg/d) for CS cows. After 10 d on a TMR, milk yields between cows that had previously been on the U or CS treatments did not differ (35.5 kg/d). When cows were switched from only pasture to a TMR, milk yield was comparable with that of cows fed CS after 10 d. Lack of carry-over effects of previous treatments and increased production suggest improvement in nutrition and the potential for greater animal well-being for cows housed in a tiestall barn and fed a nutritionally complete TMR.

Partial budgeting was used to compare income over feed costs of high-yielding Holstein cows based on data from an experiment with 4 dietary treatments arranged in a 2 x 2 factorial. The factors were low (25 kg DM/cow per day) and high (40 kg DM/cow per day) pasture allowance (PA) and supplemental grain fed at 1 kg/4 kg of milk or no supplemental grain fed. The 4 treatments were low PA unsupplemented (LPAU), low PA concentrate supplementation (LPAC), high PA unsupplemented (HPAU), and high PA concentrate supplementation (HPAC). Two management systems were modeled. The first, a fixed herd size flexible rotation length model, and the second, a flexible herd size model where rotation length was fixed. The LPAC treatment yielded the highest income over feed costs, followed by the HPAC treatment. The treatment generating the lowest income was the HPAU system. The low PA systems generated more income than did the high PA systems for equivalent supplemental feeding strategies. The results also showed that feeding supplemental grain increased the income-over-feed costs compared with systems that did not feed supplemental grain. In most treatments, comparing the fixed herd against the flexible herd models, the flexible herd size model generated higher income due to the substitution of relatively low income per hectare of hay production for higher income from milk production. There were also differences in feed conversion efficiencies for milk production due to concentrate supplementation (1.04 unsupplemented vs. 1.21 supplemented), but PA did not affect the efficiency of milk production. Neither supplementation nor PA affected the feed conversion efficiency of milk fat yield. However, the efficiency of milk protein yield was affected by concentrate supplementation (0.028 unsupplemented vs. 0.034 supplemented) but not by pasture allowance.

Significant culling of high-producing cows with low fertility reduces profitability of dairy farms as those cows are replaced with heifers. Induced lactation of nonpregnant cows may be a management alternative to reduce culling and increase profits. The objectives of this study were to evaluate the efficacy of bovine somatotropin (bST) to increase milk production in cows induced into lactation with estrogen plus progesterone, and to determine the profitability of inducing cows into lactation vs. using replacement heifers entering the herd as first-lactation cows. Parity 1 or greater, nonpregnant, healthy Holstein cows (n = 28) were induced into lactation by administration of estradiol-17beta (0.075 mg/kg of body weight [BW] per d) and progesterone (0.25 mg/kg of BW per d) for 7 d. Milking began on d 18. Cows were randomly assigned to control or bST treatment groups on d 37 +/- 20 of milking, and milk production was compared for 70 d. After the 70-d comparison, all cows received bST for the duration of lactation. Cows receiving bST produced more milk (28.4 kg/d) than controls (24.1 kg/d), with variable yields among cows. For the economic analysis, induced cows were compared to first-lactation cows in the same herd using fair market value for costs and multiple component pricing for milk. Net present value for an induced cow (1966 dollars) was significantly greater than that for a first-lactation cow (1446 dollars). Our data suggest that bST use in induced cows is profitable. If a reliable method were developed and approved by the FDA, inducing nonpregnant cows into lactation could be used by dairy producers to increase profitability.

Eighteen experiments involving 25 comparisons were reviewed to describe the main effects of fat supplementation on milk production and composition with grazing dairy cows. Results were analyzed comparing the fat supplemented and the control groups without supplemental fat, and were segmented according to the stage of lactation (early- or mid-lactation) and the degree of saturation of the fat supplement (unsaturated or saturated). Fat supplements, both saturated and unsaturated, did not affect ruminal fiber digestion. Pasture and total dry matter intake were not consistently affected by fat supplementation. Milk and 4% fat-corrected milk production were increased by 0.97 and 1.05 kg/cow per day with fat supplementation. Milk response to fat supplementation was higher in mid-lactation cows and when saturated fat sources were fed. Milk fat concentration was increased 5.1% with saturated fat supplementation and decreased 8.0% with unsaturated fat supplementation when compared to control groups. Feeding unsaturated fats increased long-chain unsaturated fatty acids in milk fat including conjugated linoleic acid. Milk protein concentration was reduced by feeding unsaturated fat supplements, although milk protein yield was not affected. The experimental results reviewed suggest that fat supplementation to the diet of dairy cows grazing high-quality pastures generally increases milk production although the effects on milk composition depend on the degree of saturation of the fat supplement.