J.G. Linn

Impact of conventional or intensive milk replacer programs on Holstein heifer performance through six months of age and during first lactation.

The objectives were to evaluate the impact of conventional or intensive milk replacer (MR) feeding programs on heifer calf performance through 6 mo of age, age at first calving, and first lactation performance. At 3 (+/-1 d) d of age, 133 Holstein heifer calves from 3 commercial dairy farms were randomly assigned, within calf source, to a conventional [20% crude protein (CP), 20% fat] or intensive MR (28% CP, 18% fat). Milk replacer treatments and percent solids were 1) conventional nonacidified (CNA), 13.9%; 2) conventional acidified (CA), 13.9%; 3) modified intensive high solids (IHS), 16.7%; 4) modified intensive low solids (ILS), 12.5%; and 5) intensive high solids, high feeding (IHSHF), 16.7%. Calves were individually housed and remained on trial for 56 d. At 2 mo of age, heifers were grouped in pens by treatment with 6 heifers per pen (4 pens per treatment). An 18.1% CP grower concentrate mix (dry matter basis) was fed to heifers that received a conventional MR and a 21.2% CP grower concentrate mix was fed to heifers that received the intensive MR preweaning. Heifers were offered 2.45 kg/d (dry matter basis) of their respective grower concentrate mix for 112 d plus free access to hay and water. At approximately 24 wk of age, heifers were transported to a second-stage grower before returning to their respective farms approximately 1 mo before calving. First-lactation performance was determined using Dairy Herd Improvement Association records. The IHSHF treatment resulted in increased calf body weight and hip height during the preweaning and early postweaning (PEP) period and the postweaning heifer grower (PHG) period as compared with the conventional (CNA and CA) or modified intensive MR treatments (IHS and ILS). Calves receiving the IHS treatment were heavier at d 56 of the PEP period compared with the conventional or ILS treatments; however, this growth advantage was not maintained in the PHG period. Feed cost per kilogram of gain during the PEP period was lowest for CNA and CA, intermediate for IHS and ILS, and highest for the IHSHF treatment. There was no effect of MR feeding program on first-lactation performance; however, heifers that received the IHSHF MR preweaning calved 27.5 d earlier than those fed a conventional MR.

Advances in Nutrition and Management of Calves and Heifers

Abstract Strides have been significant in the knowledge of calf and heifer rearing during the last 25 yr. Much information has been gathered on digestive enzymes, development of the digestive system, and metabolism. Investigations have clarified further the role of colostrum in immunity and nutrition of the young calf. Several sources of nutrients have been tested for their suitability in formulation of acceptable milk replacers and calf starters. Once-a-day feeding of milk, colostrum, or milk replacer and early weaning are practical management procedures. Labor and cost efficient methods of feeding and caring for young calves have developed. Extensive work on rearing rates and methods of rearing was published during these 25 yr. Successful schemes have evolved for feeding heifers to freshen at an optimal age and to occupy a respectful position in the milking line. Developments in housing have been phenomenal – from the calf hutch to environmentally controlled nurseries for calves. Heifer housing has ranged from relatively simple, but labor-efficient housing, to complete confinement systems. Herd health programs have developed to minimize many disease problems that can be particularly disastrous in large herds. Contract rearing of herd replacements has become a more frequently chosen option in this period. Budgets for rearing calves from birth to freshening have appeared in recommendations for raising heifers.

Crossbreds of Jersey × Holstein Compared with Pure Holsteins for Production, Fertility, and Body and Udder Measurements During First Lactation

Jersey x Holstein crossbreds (JxH; n = 76) were compared with pure Holsteins (n = 73) for 305-d milk, fat, and protein production; conception rate; days open; proportion of cows pregnant within fixed intervals postpartum; and body and udder measurements during first lactation. Cows were housed at 2 research locations of the University of Minnesota and calved from September 2003 to May 2005. The JxH were mated to Montbeliarde sires, and Holstein cows were mated to Holstein sires. Best Prediction was used to determine actual production (milk, fat, and protein) for 305-d lactations with adjustment for age at calving, and records less than 305 d were projected to 305 d. The JxH (274 kg) and pure Holsteins (277 kg) were not significantly different for fat production, but JxH had significantly less milk (7,147 vs. 7,705 kg) and protein (223 vs. 238 kg) production than pure Holsteins. The JxH had significantly fewer days open than pure Holsteins (127 vs. 150 d). Also, a significantly greater proportion of JxH were pregnant at 150 and 180 d postpartum than pure Holsteins (75 vs. 59% and 77 vs. 61%, respectively). The JxH had significantly less body weight (60 kg) at calving, but significantly greater body condition (2.80 vs. 2.71). Furthermore, JxH had significantly less udder clearance from the ground to the bottom of the udder than pure Holsteins (47.7 vs. 54.6 cm), and greater distance between front teats (15.8 vs. 14.0 cm) than pure Holsteins during first lactation.

Impact of accessibility and chemical composition on cell wall polysaccharide degradability of maize and lucerne stems.

Although lignification of forages is generally accepted as limiting cell wall degradability, prediction of degradation from cell wall composition is often difficult when forages are of similar maturity. It has been proposed that rumen microbe accessibility to potentially degradable cell walls is limited by the presence of non-disrupted cells in forage particles with lignified middle lamella/primary walls acting as barriers to microbial access. We tested this accessibility hypothesis by evaluating the impact of reducing particle size of maize and lucerne stems to the level of individual cells by ball-milling, in order to eliminate accessibility as a limiting factor. While cell wall concentration and composition were not influenced by ball-milling compared with grinding to pass a 1 mm screen in a cyclone-type mill, degradability of total cell wall polysaccharides was dramatically increased. However, only those polysaccharides (cellulose and xylan) which are most abundant in cell types with lignified middle lamella/primary and secondary walls increased in degradability owing to particle size reduction. Degradability of pectins, which are abundant in non-lignified tissues in lucerne, did not respond to ball-milling. Contrary to our expectations, ball-milled forages showed fewer correlations for cell wall composition with degradability than observed for the larger-particle-size grinding treatment. Many components of the cell wall were correlated with polysaccharide degradation for the cyclone-ground samples; however, the results were inconsistent as to which cell wall components were correlated with degradation among and within forages. This observation does not clarify the role of cell wall chemical structure as a limiting agent to wall degradation in the absence of accessibility barriers, but this study does provide support for the hypothesis that lignified middle lamella/primary walls act as barriers to microbial access for degradation.

The effect of dietary energy concentration on calf performance

Abstract At three locations, 120 calves were fed a high fat milk replacer at 10% of birth weight from d 5 through 13. On d 14, calves were assigned randomly within sex and date of birth to a 2 × 2 factorial arrangement of treatments. Treatments were (on a DM basis) high fat milk replacer (21.6%) and high fat starter (7.3%), high fat milk replacer (21.6%) and low fat starter (3.7%), low fat milk replacer (15.6%) and high fat starter (7.3%), and low fat milk replacer (15.6%) and low fat starter (3.7%). Milk replacer was fed at 8% of birth weight/d from d 14 to 35 and at 4% of birth weight/d from d 36 to 42. High fat replacer depressed DMI before and after weaning. High fat starter depressed DMI after weaning. Before weaning, calves gained more BW when fed low fat replacer. Calves fed low fat starter gained more BW after weaning. On d 56, BW were highest for calves fed low fat replacer and starter and lowest for those fed high fat replacer and starter. Growth or health of calves was not improved by fat addition to the diet.

Invited review: palmitic and stearic acid metabolism in lactating dairy cows.

Energy is the most limiting nutritional component in diets for high-producing dairy cows. Palmitic (C16:0) and stearic (C18:0) acids have unique and specific functions in lactating dairy cows beyond a ubiquitous energy source. This review delineates their metabolism and usage in lactating dairy cows from diet to milk production. Palmitic acid is the fatty acid (FA) found in the greatest quantity in milk fat. Dietary sources of C16:0 generally increase milk fat yield and are used as an energy source for milk production and replenishing body weight loss during periods of negative energy balance. Stearic acid is the most abundant FA available to the dairy cow and is used to a greater extent for milk production and energy balance than C16:0. However, C18:0 is also intimately involved in milk fat production. Quantifying the transfer of each FA from diet into milk fat is complicated by de novo synthesis of C16:0 and desaturation of C18:0 to oleic acid in the mammary gland. In addition, incorporation of both FA into milk fat appears to be limited by the cows requirement to maintain fluidity of milk, which requires a balance between saturated and unsaturated FA. Oleic acid is the second most abundant FA in milk fat and likely the main unsaturated FA involved in regulating fluidity of milk. Because the mammary gland can desaturate C18:0 to oleic acid, C18:0 appears to have a more prominent role in milk production than C16:0. To understand metabolism and utilization of these FA in lactating dairy cows, we reviewed production and milk fat synthesis studies. Additional and longer lactation studies on feeding both FA to lactating dairy cows are required to better delineate their roles in optimizing milk production and milk FA composition and yield.

Crossbreds of Jersey × Holstein Compared with Pure Holsteins for Body Weight, Body Condition Score, Dry Matter Intake, and Feed Efficiency During the First One Hundred Fifty Days of First Lactation

Jersey x Holstein crossbred (JxH) cows (n = 24) were compared with pure Holstein cows (n = 17) for body weight, body condition score, dry matter intake (DMI), and feed efficiency during the first 150 d of first lactation. Cows were housed in the University of Minnesota dairy facility at the St. Paul campus and calved from September 2004 to January 2005. The JxH cows were mated by artificial insemination with Montbeliarde bulls, and Holstein cows were mated by artificial insemination with Holstein bulls. Cows were weighed and body condition was scored every other week. Cows were individually fed a TMR twice daily, and feed refusals were measured once daily. The DMI of cows was measured daily and averaged across 7-d periods. Milk production and milk composition were from monthly Dairy Herd Improvement records. Best Prediction was used to calculate actual production (milk, fat, protein) for each cow from the 4th to 150th day of first lactation. The JxH cows had significantly less body weight (467 vs. 500 kg) and significantly higher body condition scores (2.90 vs. 2.76) than pure Holstein cows. The JxH cows had significantly less milk production (4,388 vs. 4,644 kg) during the 4th to 150th day of lactation than did pure Holstein cows. However, fat plus protein production during the first 150 d of lactation was not significantly different for JxH (302 kg) and Holstein (309 kg) cows. The JxH and pure Holstein cows did not differ significantly for daily DMI (22.0 vs. 22.7 kg, respectively), and the JxH (4.7%) and pure Holstein (4.5%) cows consumed similar DMI based on percentage of body weight. Consequently, feed efficiency for the 4th to 150th day of lactation did not differ for JxH and pure Holstein cows.

Short communication: Jersey × Holstein crossbreds compared with pure Holsteins for production, mastitis, and body measurements during the first 3 lactations

Jersey (JE)×Holstein (HO) crossbred cows (n=76) were compared with pure HO cows (n=73) for 305-d milk, fat, and protein production, somatic cell score (SCS), clinical mastitis, lifetime production, and body measurements during their first 3 lactations. Cows were in 2 research herds at the University of Minnesota and calved from September 2003 to June 2008. Best prediction was used to determine actual production for 305-d lactations as well as lifetime production (to 1,220 d in the herd after first calving) from test-day observations. During first lactation, JE×HO cows and pure HO cows were not significantly different for fat plus protein production; however, JE×HO cows had significantly lower fat plus protein production during second (-25 kg) and third (-51 kg) lactation than pure HO cows. Nevertheless, JE×HO cows were not significantly different from pure HO cows for lifetime production or lifetime SCS. The JE×HO cows were not significantly different from pure HO cows for SCS and clinical mastitis during first and second lactations; however, JE×HO cows tended to have higher SCS (3.79) than pure HO cows (3.40), but significantly lower (-23.4%) clinical mastitis during third lactation. The JE×HO cows had significantly less hip height, smaller heart girth, less thurl width, and less pin width than pure HO cows during the first 3 lactations. Furthermore, JE×HO cows had significantly less udder clearance from the ground and significantly greater distance between the front teats than pure HO cows during their first 3 lactations.

Effects of milk replacer program fed 2 or 4 times daily on nutrient intake and calf growth1

The aims of this study were to determine if feeding frequency (FF) of milk replacer (MR; meals/d) alters starter intake, growth, and efficiency of growth in nursery calves fed a conventional or accelerated MR. We hypothesized that smaller and more frequent MR meals would increase starter intake and growth when greater amounts of MR nutrients are fed to nursery calves. Forty-eight Holstein and Holstein-cross heifer and bull calves were assigned to treatments in a 2 × 2 factorial arrangement of MR and FF. Treatments included (1) standard 20% CP and 20% fat MR fed at 1.5% of body weight (BW; 2 meals/d; STD2), (2) standard 20% CP and 20% fat MR fed at 1.5% of BW (4 meals/d; STD4), (3) modified 26% CP and 18% fat MR fed at 2.0% of BW (2 meals/d; MOD2), and (4) modified 26% CP and 18% fat MR fed at 2.0% of BW (4 meals/d; MOD4; n=12). All calves were fed at 0600 and 1700 h and STD4 and MOD4 calves were fed 2 additional meals at 1100 and 1400 h, resulting in the same amount of MR offered for the 2 × and 4 × treatments. Treatments were fed from d 2 to 42 of age and all MR feeding rates were adjusted weekly to maintain MR solids intakes at 1.5 or 2.0% of BW for STD and MOD diets, respectively, and were reconstituted to 15% total solids. Milk replacer FF was reduced by 50% on d 36 and calves were weaned on d 42. Calves were housed in hutches bedded with straw and offered water and a texturized 18% CP starter ad libitum. Calf body weight and body structure were measured weekly and starter intake and fecal scores were measured daily. Through both 42 and 56 d, calves fed MOD had greater CP and fat intake, resulting in increased average daily gain, heart girth, circulating nonesterified fatty acids (NEFA), and muscle total lipid compared with calves fed STD diets. Calves fed MOD diets consumed less starter grain than STD calves but total dry matter intake was similar among treatments. Increased FF for STD calves resulted in greater starter intake at weaning but increasing FF of MOD calves did not have this effect. Due to differences in starter intake, total dry matter by calves through d 56 was similar across treatments. Additionally, increased FF tended to increase serum NEFA concentrations. Serum NEFA concentration was negatively correlated with starter intake. The BW of calves fed STD2 and STD4 treatments almost doubled and the BW of calves on the MOD2 and MOD4 treatments doubled by d 56. Increased FF of the conventional MR program but not accelerated MR program increased starter intake. Increased FF did not affect growth, starter intake, or gain:feed ratio.

Birth traits of pure Holstein calves versus Montbeliarde-sired crossbred calves.

Pure Holstein calves and Montbeliarde-sired crossbred calves from multiparous Holstein dams were compared for gestation length, calf weight at birth, calving difficulty, and stillbirth in 2 research herds of the University of Minnesota. The Montbeliarde-sired calves from multiparous Holstein dams had significantly longer gestation lengths (283.2 d) than Holstein-sired calves from Holstein dams (278.4 d), and Montbeliarde-sired calves from multiparous Holstein dams had significantly greater calf weight at birth (48.3kg) compared with Holstein-sired calves from Holstein dams (43.3kg). However, calves sired by Montbeliarde bulls were not significantly different from calves sired by Holstein bulls for calving difficulty and stillbirth. In addition, Jersey x Holstein crossbred cows mated to Montbeliarde artificial insemination (AI) bulls were compared with pure Holstein cows mated to Holstein AI bulls for gestation length, calf weight at birth, calving difficulty, and stillbirth at their first 3 calvings. Gestation length was significantly longer for Jersey x Holstein cows bred to Montbeliarde bulls than for pure Holstein cows bred to Holstein bulls at first calving (280.3 versus 277.7 d) and second and third calving (282.2 versus 278.6 d); however, Jeresy x Holstein cows bred to Montbeliarde AI bulls were not significantly different from pure Holstein cows bred to Holstein AI bulls for calf weight at birth, calving difficulty, and stillbirth at the first 3 calvings.