This study was conducted to determine the effect of modified crude protein (CP) concentrations and a supplemental directed microbial in the milk replacer fed to Holstein calves during elevated ambient temperatures. Fortyour Holstein calves were randomly assigned treatments in a 2x2 factorial arrangement of treatments. Weekly and daily measurements were taken and analyzed using PROC MIXED in SAS. Calves fed increased CP concentrations in the milk replacer had greater body weight and frame measurements during the pre-weaning phase and at weaning. Directed microbial supplementation led to increased ADG during the post-weaning phase. Directed microbial supplementation and milk replacer modification helped alleviate heat stress through decreased rectal temperatures and rectal scores. Directed microbial supplementation increased fecal scores. Calves fed the control diet had greater volatile fatty acid concentrations in the rumen fluid, showing signs of increased rumen papillae development.

The objective of this study was to evaluate the effects of heat stress and varying levels of milk replacer on dairy calf performance. Holstein bull calves ≤ 2 d of age were randomly assigned housing, outside under a covered area, heat stress (HS), or inside a controlled environment, non-heat stress (NHS), to test for heat stress effects on growth. Calves were also assigned to one of three feeding strategies: increasing amounts of milk replacer from 1.1% body weight (BW) to 1.5% BW (INC), constant at 1.1% BW (CON), or decreasing from 1.6% BW to 1.2% BW (DEC), adjusted weekly, commencing on day 9 of feeding and ending on day 40. Milk replacer amounts were adjusted twice weekly after weighing. Calves had ad libitum access to commercial starter feed and water. Starter intake, water intake, and fecal score (1 to 4) were recorded daily. Respiration rates and rectal temperatures were recorded twice daily at 0600h and 1800h. Average daily gain was greater (P < 0.01) for NHS (0.79 ± 0.03 kg/d) compared to HS (0.66 ± 0.03 kg/d) The NHS calves consumed more starter (P < 0.01) than HS (1.77 vs 1.16 ± 0.06 kg/d. Water consumption averaged 3923 ± 105 mL/d for HS which was greater (P < 0.01) than NHS (2338 ± 105 mL/d). No significant differences were observed among the feeding treatment groups for weight gain (P = 0.73). Milk replacer levels had a significant impact (P < 0.01) on the amount of calf starter consumed with CON consuming the most (1.64 ± 0.07 kg/d), followed by INC (1.44 ± 0.07) and DEC consuming the least (1.34 ± 0.07 kg/d). Water intake was also significantly impacted by milk replacer levels (P < 0.01). Calves in the DEC group consumed the least amount of starter, and consumed more water (3657 ± 129 mL/d) than both INC calves (3119 ± 129 mL/d) and CON calves (2614 ± 129 mL/d). Overall, housing has an impact on growth in neonatal dairy calves; however, milk replacer levels did not impact growth of the calves.

This trial was conducted in two phases during the period of February 2002 – June 2003. In phase 1 of the study the growth potential of calves fed either commercial Surromel Calf® (CSM) or experimental Surromel Calf (ESM) without calf starter was evaluated. In phase 2 of the study calves were fed either experimental Surromel Calf (ESM) or full milk with starter. High production cost and the availability of new technology prompted Clover SA to investigate other processes of manufacturing Surromel Calf®. The implementation of a new manufacturing process however, also necessitates evaluation of the end product. Twenty four Holstein heifer calves were used in a completely randomized block design. Calves were liquid fed only. For the first two weeks the milk replacer was allocated at 10% of body weight (2l fed twice daily), from week 3 to week 6 at 12.5% of body weight (2.5l fed twice daily) and during week 7 and week 8 calves received the milk replacer at 15% of body weight (3l milk fed twice daily). Water was available ad lib except for 30 minutes before and after milk replacer feedings. Body weight and skeletal development (body length, shoulder height, shoulder width and chest diameter) were measured weekly. The fecal consistency was subjectively scored daily. Mean average daily gains were 170g/day and 176g/day for calves receiving either ESM or CSM respectively. No differences were observed between treatments (P>0.05) for any change in body stature measurements over the 56 day trial period. If a price-competitive milk replacer could guarantee similar growth results as full milk, then milk producers would have confidence in using these replacers instead of full milk. In phase 2 of the trial calves were fed either 2l of full milk (FMS) or experimental Surromel Calf (EMSS) twice daily from birth up to 56 days. Calves had ad lib access to a commercial calf starter. Starter consumption was negligible for the first three weeks. Starter intake was 0.30kg/d and 0.34kg/d respectively at 35 days of age and 1.11kg/d and 1.10kg/d for FMS and EMSS calves respectively at 56 days (P>0.05). The average daily gain (ADG) were 370g/day and was unaffected by treatment (P>0.05). No differences were observed between treatments (P>0.05) for any change in body stature measurements. Growth standards for dairy calves with body weight less than 100kg have been included for the first time in the NRC Dairy 2001. Many producers are reluctant to use these recommendations since these have not been validated under South African conditions. The growth prediction was only compared with the growth of calves in Phase 2. The results showed that the NRC growth predictions are in agreement from week 3 onwards with the current study‘s growth results. / Dissertation (MSc (Agric) : Animal Nutrition)--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

In experiment one, week old Jersey bull calves (n=39) were assigned to one of four diets: 21/21 (n=8), 27/33 (n=8), 29/16 (n=9), MILK; or a baseline sacrifice group (n=6). Diets 21/21, 27/33, and 29/16 were milk replacers containing 21, 27, or 29% CP, and 21, 33, and 16% fat, respectively. Diet 21/21 was fed at 15% of BW. Diets 27/33, 29/16, and MILK supplied 180g CP/d. Calves were fed 4 wk. Weight, hip height, wither height, heart girth, and body length were measured weekly. Weekly plasma samples were analyzed for PUN, NEFA, and glucose. Calves were processed to estimate body composition. Feed efficiency and ADG were greatest for calves fed MILK, least for calves fed 21/21, and intermediate for calves fed 29/16 and 27/33. Calves fed 27/33 or MILK had the greatest gains of fat and percentage fat in the empty body. Body fat percentage of calves fed 29/16 or 21/21 was not changed by diet. Performance of calves fed 27/33 and 29/16 was similar except that calves fed 29/16 were leaner and calves fed 27/33 had a propensity for elevated NEFA. Feeding 180g of CP in the MR was beneficial to calf performance compared with diet 21/21. In experiment two, tissues from a subset of calves [21/21 (n=4), 27/33 (n=5), 29/16 (n=5), MILK (n=3), baseline (n=2)] were scanned using dual energy x-ray absorptiometry to estimate mass, fat, CP, and ash. Liver, organ, and carcass mass by DXA were correlated to scale weights (R²⁺= 0.99, 0.62, and 0.79, respectively). DXA was a poor predictor of percentage fat, CP, and ash (adjusted R²⁺ <0.10). Experiment three determined level of calf mortality in the United States; and identified opportunities to reduce mortality. Herds (n=88) were representative of the US Jersey population. Production averaged 7180 ± 757 kg milk annually. Herds averaged 199 births annually. Mortality was 5.0% from birth to 24 h (M24) of life and 6.7% from 24 h to 3 mo of life (M3). Level of mortality (M24) was highest in herds that calved on pasture. Lower levels of mortality (M3) were associated with use or maternity pens and earlier weaning. / Ph. D.

In the first experiment, 132 Jersey calves were assigned to one of three diets on three farms. Diet 20/20, 28/25, and 28/20 were milk replacers (MR) consisting of 20%, 28%, and 28% CP, and 20%, 25%, and 20% fat, respectively. Diet 20/20 was reconstituted at 10% DM solids, whereas diets 28/25 and 28/20 were reconstituted at 12.5% DM solids. Body weight, body length, hip height, wither height, heart girth, and hip width were measured weekly. An initial plasma sample was analyzed for IgG concentration to test for passive immunity. Calves remained on study for 8 wk. Body weight gain, ADG, total weight gain, and stature measurements were greatest for calves fed 28/25 and lowest for calves fed diet 20/20, whereas calves fed 28/20 were intermediate. In the second experiment, 70 calves were assigned to one of two treatments. Calves included purebred Holsteins, Jerseys, and crossbred reciprocals. Calves were assigned to diet 20/20, which was reconstituted to 10% DM solids or diet 28/20, which was reconstituted to 13% DM solids. Body weight, body length, hip and wither heights, heart girth, and hip width were measured weekly. Plasma samples were collected weekly for analysis of PUN, glucose, and total proteins. Body weight gain, ADG, and total weight gain were greatest for calves fed 28/20 and least for calves fed diet 20/20. Therefore, feeding calves a 20/20 MR at 10-15% of their BW results in lower BW gain, ADG, total weight gain, and stature measurements. / Master of Science

The objective of this study was to determine amount and composition of waste milk (WM) generated by 13 dairy farms and to measure effectiveness of on-farm pasteurizers. Waste milk was sampled bi-weekly from three farms located in North Carolina (NC) for 28 weeks and twice from ten farms in California (CA) in June 2005 and Jan. 2006. Amount of waste milk generated ranged from 2.48 – 9.84 L/calf/d. Standard plate count (SPC) of waste milk before pasteurization averaged 17 million cfu/ml on NC farms and 1.6 million cfu/ml on CA farms. Pasteurizers failed to deactivate alkaline phosphatase in 16%, and <5% of the time in NC and CA. California WM had lower post pasteurized SPC (13,000 cfu/ml) than NC farms (430,000 cfu/ml). A feeding trial was conducted to evaluate supplementing WM with 28% protein: 20% fat milk replacer (28:20) when WM is insufficient relative to calf demands. Treatment (TRT) 1 calves received M for 28d and then 28:20 until weaning at 56d. Treatment 2 calves received 28:20 for 28d and then milk until weaning. Treatment 3 calves received 28:20 for the entire period Four periods of time were evaluated; the total period, first four weeks (P1), transition period (TP), in which calves were switching diets, and until weaning (P2). Treatment 1 ADG was higher during TP as compared to TRT 2. Results demonstrated that similar growth rates through 8 weeks of age was achieved with either combination of M and 28:20 or only 28:20 fed on an isocaloric basis. / Master of Science

Current data indicates that feeding dairy calves more nutrients in early life allows them to produce more milk in the future. Mechanisms responsible are poorly understood. Thirty-six Holstein heifer calves were fed either a restricted (R; 20.2% crude protein [CP], 19.8% fat, dry matter (DM) basis, fed at 0.44 kg/hd/d, DM basis) or an enhanced (EH; 28.9% CP, 26.2% fat, DM basis, fed at 1.08 kg/hd/day, DM basis) milk replacer (MR) and given either a placebo or estradiol (E2) implant to assess differential responses to E2. Our underlying hypothesis was that calves fed more nutrients are better able to respond to mammogenic stimuli and will have a more developed mammary gland as a result of imposed treatments. Enhanced-fed calves grew at a faster rate, were heavier at weaning, and had more functional mammary tissue (i. e., parenchyma; PAR) mass in the mammary gland at weaning (7.3-fold). Additionally, biochemical composition of the PAR was not impacted by the dietary treatments imposed. Furthermore, EH-fed calves had an increase in the number of actively dividing cells throughout the mammary PAR as well as increased intensity of estrogen receptor expression in the population of cells expressing the estrogen receptor. Enhanced-fed calves had an up-regulation of genes and pathways in the PAR related to metabolism, cellular signaling, and cellular growth. When given E2, EH-fed calves experienced the greatest overall mammary gland development and had the greatest PAR mass without compromised composition. When comparing EH- and R-fed calves given E2, differential expression of genes and pathways related to cell growth, cell signaling, and metabolism was observed. In summary, data indicates that enhanced feeding of calves in early life allows increased responsiveness to mammogenic stimuli and a corresponding increase in mammary development. We suggest that this may at least partly explain the improved future milk production in calves fed in this manner. / Ph. D.

Raising replacement heifers consumes a large portion of dairy and beef producers' income. An ultimate goal of producers is to decrease inputs and maximize outputs to produce fertile replacement heifers. Manipulating early postnatal growth and development through diet enables this practice to be successful. Puberty is greatly influenced by body weight (BW). Once heifers reach puberty, they become fertile and can achieve their reproductive potential. Growth can easily be influenced during the preweaning phase of development. Offering calves a higher plane of nutrition through milk diets prior to weaning hastens development and can lead to an earlier age at the onset of puberty. The objective of the first study was to understand how plane of nutrition influences BW, bone mineralization, and organ growth during the preweaning phase of development in Holstein calves. Calves offered a higher plane of nutrition experienced greater BW gains, increased bone mineralization, and accelerated organ growth. The second study evaluated plane of nutrition on reproductive development, specifically adenogenesis in Holstein heifer calves. Adenogenesis, or the development of uterine glands, is initiated in the early postnatal period. It involves rapid endometrial epithelial cell proliferation, germinal bud formation, invasion into the stroma, and extensive branching and coiling. Little is known about how nutrition impacts adenogenesis in ungulates, however, this study provided validation that it does drive gland formation. Additionally, this study assessed the influence of exogenous estradiol on reproductive development and adenogenesis when given after the completion of adenogenesis. We can confirm that exogenous estradiol given after the completion of adenogenesis does not alter the outcomes of gland formation. The beneficial effects of feeding a higher plane of nutrition to calves prior to weaning on bone mineral density, organ growth, and adenogenesis may provide new possibilities for understanding the impacts of early nutrition on calf immune responses and productive lifespan of the cow. Collectively, these studies emphasize the importance of nutrition during preweaning growth and development of Holstein calves. / Master of Science

Free-access acidified milk feeding is increasingly being adopted to feed dairy and veal calves. Acidification is used to preserve milk and facilitate free-access feeding. There is, however, little controlled research to support the adoption of free-access acidified milk feeding over traditional feeding programs. The objectives of this thesis were to describe the preweaned calf management and feeding practices used on dairy farms in Ontario, Canada, and to investigate the effects of milk replacer acidification and free-access feeding on the productivity and welfare of calves. A total of 140 Ontario dairy producers participated in a cross-sectional study and were surveyed about on-farm calf management and feeding practices. Results from this study documented that there are currently a range of management practices and several different feeding programs being used on farms. Colostrum and milk feeding management are the areas where the most progress has been made in recent years; however, several other aspects of calf management and feeding still warrant improvement. A pilot study was conducted to examine the effects of milk replacer acidification and free-access feeding on the nutrient intake, growth, rumen papillary development and behaviour of calves. A field study was designed to evaluate the effects of a free-access acidified milk replacer feeding program on the pre and postweaning health and growth of dairy and veal calves. A randomized controlled study was completed to investigate how milk replacer acidification, under free-access feeding conditions, affects the pre and postweaning performance and health of veal calves. Results from these studies demonstrated that milk replacer acidification limited calves’ intake of milk replacer by approximately 1 L/d, resulted in more fragmented feeding behaviour, promoted earlier solid feed intake and tended to support improved respiratory health, but had little impact on rumen development or long-term calf performance. Moreover, free-access feeding facilitated larger intakes of milk, resulted in fewer signs of hunger or frustration, and supported greater preweaning growth, but delayed the onset of solid feed consumption and appeared to negatively affect rumen development, compared to restricted feeding. Collectively, these results demonstrate that free-access acidified milk feeding promotes greater early life productivity and enhances calf welfare. / Ontario Ministry of Agriculture, Food and Rural Affairs, Dairy Farmers of Ontario, Ontario Veal Association, National Sciences and Engineering Research Council, Grober Nutrition and 3M Canada

Orientador: Ciniro Costa / Resumo: Trinta bezerros holandeses foram distribuídos em delineamento em blocos casualizados (5 blocos e 6 tratamentos) no Setor de Bovinocultura de Leite da Universidade de Marília para se avaliar o seu desempenho até o desaleitamento para a produção posterior de vitelos de carne rosa com seis rações isoprotéicas (22,5% PB) e isoenergéticas (3,2 Mcal EM/kg MS) feitas com: milho seco moído (MSM), silagem de grãos úmidos de milho (SGUM), sorgo seco com tanino moído (SCTM), silagem de grãos úmidos de sorgo com tanino (SGUSCT), sorgo seco sem tanino moído (SSTM) ou silagem de grãos úmidos de sorgo sem tanino (SGUSST). Os animais receberam sucedâneo de leite até atingirem o peso pré-estabelecido para desaleitamento de 60 l 5 kg. Não houve efeito de tratamento (P > 0,05) para as variáveis analisadas: altura de cernelha e idade ao desaleitamento, consumos diários e totais de sucedâneo e de ração, ganhos de peso diários e totais e também conversão alimentar. As rações contendo SCTM, SGUSCT, SSTM ou SGUSST apresentaram menores custos por kg de ganho de peso do que as rações com MSM ou SGUM. Concluiu-se que todos os alimentos avaliados podem ser usados em rações para bezerros em fase de aleitamento sem comprometimento do seu desempenho e conferindo resultados similares. / Abstract: Thirty Holstein veal calves were distributed in a complete randomized blocks experimental design (5 blocks, 6 treatments) at Dairy Cattle Production Department, Universidade de Marília - SP, to evaluate their performance until wean to posterior production of non-special-fed veal with six rations (22,5% CP and 3,2 Mcal EM/kg MS) with: dry ground corn (DGC), high moisture corn silage (HMCS), dry ground sorghum with tannin (GSWT), high moisture sorghum with tannin silage (HMSWTS), dry ground sorghum without tannin (GSWTT) or high moisture sorghum without tannin silage (HMSWTTS). The animals were nursed with milk replacer and weaned at 60 l 5 kg weights. The treatments did not affect (P > 0.05) the variables: shoulder height and age at wean, milk replacer and ration dry matter daily and total intakes, daily and total weight gains and dry matter conversion. Rations containing GSWT, HMSWTS, GSWTT or HMSWTTS, showed lower costs per kg of weight gain in comparison to rations with DGC or HMCS. In conclusion, all feeds evaluated can be used on rations to veal calves in nursing phase and confers similar results. / Doutor